CONTROLLING FRUIT FUES

BY THE STERILE-INSECT TECHNIQUE

PRO CEED ING S OF A PANEL AND RESEARCH CO-ORDINATION MEETING

ORGANIZED BY THE JOINT FAO/IAEA D IV IS IO N OF ATOM IC ENERGYIN FOOD AN D AGRICULTURE

¿íkj IN T E R N A T IO N A L A T O M IC EN ERG Y AGENCY, V IENNA, 1 975

CONTROLLING FRUIT FLIES BY THE STERILE -INSECT TECHNIQUE

PANEL PROCEEDINGS SERIES

CONTROLLING FRUIT FLIES BY THE STERILE-INSECT TECHNIQUE

PROCEEDINGS OF A P A N E L AND RESEARCH CO-ORDINATION MEETING

ON THE STER ILE -M ALE TECHNIQUE FOR CONTROL OF FRUIT FLIES

ORGANIZED B Y THE JOINT FAO/IAEA DIVISION OF ATOM IC ENERGY

IN FOOD AND AGRICULTURE AND HELD IN V IENNA , 12-16 NOVEM BER 1973

INTERNATIO NAL ATOM IC ENERGY AG ENCY VIENNA, 197 5

CONTROLLING FRUIT FLIES BY THE STERILE-INSECT TECHNIQUEIAEA, VIENNA, 1975

STI/PUB/392 ISBN 92-0 —111575—X

Printed by the IAEA in Austria November 1975

FOREWORD

The effectiveness o f the sterile-insect technique (S IT ) was amply demonstrated even before the recent steep rises in oil prices. With the increasing cost o f oil-derived insecticides, the SIT becomes all the more important since the efficient use o f this technique depends on minimizing the application o f insecticides and maximizing the utilization o f local resources. In this context the SIT is an effective and environment-sparing alternative to indiscriminate use o f chemical control, and is especially significant for developing countries with their limited foreign exchange and still relatively unpolluted environments. Many o f these countries rely heavily on agricultural exports o f fruit and fruit products for their foreign exchange. Appropriately, most SIT campaigns up to now have been directed against fruit flies.

Since the previous FAO/IAEA panel on the control o f fruit flies by the SIT, published by the IA E A in 1970 under the title “ Sterile-male Technique for Control o f Fruit Flies” , much progress has been made and aspects o f the SIT so far ignored or neglected have come to receive increasing attention. Among these aspects is quality control by flight-mill studies, mating speed, and measurement o f genetic distance between populations by allozyme analysis. In addition, new field operations using sterile releases and related techniques have been carried out against such pests as medfly, melon fly, cherry fruit fly, olive fly and onion fly. A panel and research co-ordination meeting to survey these developments was held by the Joint FAO /IAEA Division o f Atom ic Energy in Food and Agriculture in Vienna on 12—16 November 1973 and the present book contains the proceedings o f that combined meeting.

Since then insecticides have become even more costly, and the containment o f fruit flies by methods less reliant on insecticides has taken on a new urgency. The need for such fruit-fly containment and for its timely application can be strikingly illustrated by an example taken from Central America. The Mediterranean fruit fly, which first appeared in the 1950s in Central America, has surged northward throughout this area and is now poised to invade Mexico. The economic significance o f an unchecked spread o f this pest is reflected in an estimated annual loss o f S6.8 million for the Central American area excluding British Honduras and Mexico. Should the medfly invade those two countries, their citrus industries would suffer a combined annual loss o f $6 million. Should the medfly go unchecked and invade the United States, the US fruit industry would lose annually about $85 million for citrus and $200 million for deciduous fruits. These figures come from “ Economic Survey o f the Mediterranean Fruit Fly in Central America” , USDA/USAID Field Report No. 21, by R.G. Henning et al. (1972).

This situation in Central America has revived interest in the Joint UNDP/OIRSA/IAEA co-operative project. Seven countries in this area collaborated in the project from 1965 to 1970; although the outcome was a successful demonstration o f medfly suppression by the SIT, there was unfortunately no practical sequel to it. In 1974, remedying this situation would have required the investment o f an estimated $20 million in a five-year campaign o f eradication culminating in area-wide releases o f sterile medflies. In spite o f this heavy cost, eradication was still at that time considered a feasible and economically possible proposition. Now, however, in 1975, prices have rocketed so steeply and the pest has spread so widely that eradication may no longer be economic or practicable, and containment including the use o f guardian populations o f sterile flies may be a last resort. Because o f its particular relevance this book includes as an appendix a paper by R.H. Rhode, originally planned for the 1974 IA E A Symposium in Innsbruck on the Sterility Principle for Insect Control. This paper describes some o f the organizational, strategic and technical aspects o f what, under Central American conditions, has become a formi­dable undertaking.

It is hoped that the present book will be a useful addition to the series o f panel and symposium proceedings published by the IA E A on the sterile-insect technique, and will encourage redoubled efforts in the use o f this non-polluting method o f controlling fruit flies.

CONTENTS

The sterile-insect technique for the control o f fruit flies: a survey(IAEA-PL-582/1).................................................................................................................... 3E J. Harris

Genetic variation in natural insect populations and its bearing on mass-rearingprogrammes (IAEA-PL-582/2).............................................................................................. 9G.L. Bush

Quality in mass-produced insects: definition and evaluation (IAEA-PL-582/3) ............... 19D.L. Chambers

Progress o f the pilot test at Lanai against Mediterranean fruit flies and melon flies(IAEA-PL-582/4).................................................................................................................... 33E.J. Harris, R. T. Cunningham, N. Tanaka, К Ohinata

The Procida medfly pilot experiment: status o f the medfly control after two years o fsterile-insect releases (IA E A -PL-582/5 )............................................................................... 39U. Cirio

Genetic control o f Ceratitis capitata', practical application o f the sterile-insect technique(IAEA-PL-5 82/20) ............................................................................................................... 51L. Mellado, P. Ros, M. Arroyo, E. Castillo

Application o f the sterile-insect technique for control o f Mediterranean fruit flies inIsrael under field conditions (IA E A -PL-582/6 )................................................................. 67S.S. Kamburov, A. Yawetz, D.J. Nadel

Application o f S IT on the European cherry fruit fly, Rhagoletis cerasi L., in northwestSwitzerland (IAEA -PL-582/7 ).............................................................................................. 77E.F. Boiler, U. Remund

Small-scale field experiments on sterile-insect control o f the onion fly, Hylemya antiqua(Meigen) (IA E A -PL -582/8 ).................................................................................................. 83J. Theunissen, M. Loosjes, J.Ph.W. Noordink, J. Noorlander, J. Ticheler

Mass rearing o f the olive fruit fly, Dacus oleae (Gmelin), at ” Democritos”(IAEA-PL-5 82/9). . ................................................................................................................ 93J.A. Tsitsipis

Comparative behaviour o f lab.-cultured and wild-type Dacus oleae flies in the field(IAEA-PL-582/10) ............................................................................................................... 101R.J. Prokopy, G.E. Haniotakis, A.P. Economopoulos

PROGRESS REPORTS

Summaries o f work done at various institutions .................................................................... 109

SEIBERSDORF CONTRIBUTIONS

PR IN C IPAL PAPERS

Contributions from staff o f the Seibersdorf Laboratory, IAEA , Vienna 127

STATEM ENTS AND RECOMMENDATIONS

General statements and recommendations ............................................................................ 149Specific statements and recommendations ............................................................................ 152Appendix IA medfly eradication proposal for Central Am erica............................................................... 159

R.H. Rhode Appendix 11Report o f the Illrd meeting o f the IOBC/WPRS working group on genetic control o f the

Mediterranean fruit f l y ........................................................................................................ 167

List o f Participants 173

PRINCIPAL PAPERS

IAEA-PL-582/1

THE STERILE-INSECT TECHNIQUE FOR THE CONTROL OF FRUIT FLIES

A survey

E.J. HARRIS

Hawaiian Fruit Flies Lab.,USDA, ARS,Honolulu, Hawaii,United States o f America

Abstract

THE STERILE-INSECT TECHNIQUE FOR THE CONTROL OF FRUIT FLIES: A SURVEY.Some advantages of the sterile-insect technique (SIT) are its minimum contribution to environmental

pollution and its minimum adverse effect on non-target organisms. A review is made of the melon fly and sterile Mediterranean fruit fly release programmes, the accomplishments, and the implications. Recom­mendations are made for research leading to development of methods for practical use of the SIT.

INTRO D UCTIO N

In the United States in recent yea rs , the s te r ile - in sec t technique (S IT ) has em erged as an im portant approach to b io log ica l control of pest insect species and an a lternative to chem ical control. Th is technique (h ere , this te rm means the re lea se of s te r ile male and fem ale insects ) of controlling fru it f l ie s (T eph ritidae ) was adopted ea r ly in Hawaii (S teiner et a l., 1962, 1965), not long a fter Knipling reported on this b io -con tro l princip le and Baum hover et al. (1955) dem onstrated its p ractica lity . Subsequently, other tests of the technique w ere made by Cheikh et al. (1975), de Murtas et al. (1970), LaB recque and K e lle r (1965), Lopez-D . (1970), M ellado et al. (1970), M onro (1965), Rhode et al. (1971), Shaw and R iv ie llo (1965), Steiner (1969), and Steiner et al. (1962, 1965).

The duty of this panel is to rev iew the research involving SIT, to note the p rogress made, and to determ ine what needs to be done to acce lera te p rogress toward the ultim ate goal, the routine use of the SIT fo r p ractica l control of fru it flie s .

PRO G RAM M E REVIEW

Trends toward in tegrated control (Stern e ta l., 1959) and pest manage­ment p rogram m es that invo lve the use of parasites, predators, and insectic ides have recen tly becom e pronounced (Huffaker, 1971). Th is approach is a lo g ica l developm ent since it should avoid o r m in im ize the developm ent of insect res is tance to pestic ides, reduce the amounts of pestic ide used, and avoid the e levation of secondary pests to the status of m a jor pests as a resu lt of the destruction of b en e fic ia l insects. H ow ever, e ffec tive in tegrated con tro l and pest management requ ire basic in form ation about the eco logy and seasonal populations of the ta rget species, about th e ir parasites and

3

4 HARRIS

predators, and about other elem ents in the insect fauna. L ikew ise , the e co ­system of the pest insect must be m onitored constantly during control operations to determ ine or pred ict e ffects on the pest species and other species. Th is same in form ation and thinking is a lso mandatory when the SIT is to be used. Indeed, alm ost a ll in telligen t methods of insect control requ ire eco lo g ica l knowledge, but the SIT n orm ally requ ires v e ry much m ore, fo r exam ple, data on d ispersa l, m igration , mating habits, and density.

Th ere are few disadvantages to the SIT i f it is used when it w ill work.F o r exam ple, it was used successfu lly by the Hawaiian F ru it F lie s Labora tory to erad icate the melon fly , Dacus cucurbitae Coquillett, from Rota in 1963 (S teiner e ta l., 1965). A lso , eight incipient outbreaks (undoubtedly started by cyclon ic winds ca rry in g f l ie s from Guam 37 m iles away) have been stopped on Rota during the last 10 years . These successes are good e v i­dence of the e ffec tiven ess of the technique when it is used properly : the method w ill erad icate pests and w ill contain outbreaks at minimum cost. H owever, the technique has not always been successfu l against the m elon fly . F o r exam ple, when it was used in Guam between 1969 and 1972 (Governm ent of Guam, Department of A gricu ltu re , unpublished data), the s te r ile flie s proved to be non-com petitive, and the m onitoring system inadequate; also, the topography o f the island was such (eco lo g ica l niches in which la rge numbers of the f ly could breed undetected) that re in festa tion of c leared areas occu rred quickly.

The success of the SIT against the M editerranean fru it fly , C era titis capitata (W iedem ann), a lso depends on care fu l planning. How ever, in terest in suppressing this species is high because of the m ed fly 's worldw ide econom ic im portance. As a resu lt, re lea ses of s te r ile m ed flies have been made in Hawaii, Ita ly , Spain, Cyprus, Peru , A rgentina, Austra lia , Chile and Is ra e l, and, m ore recen tly , in Costa R ica and Tunisia. The most im portant of these tests , because of the s ize and the potential fo r p ractica l control, w ere those made in Costa R ica and Tunisia. The e ffo rts o f Rhode e ta l. (1971) ach ieved successfu l suppression of the m ed fly in Costa Rica.A lso , Cheikh e ta l. (1975) reported sa tis factory resu lts against the m edfly in Tunisia.

The SIT is young and is evolving. Th is evolution must proceed in a reasonable way. L e t us th ere fo re look at these most recen t e ffo rts to use the technique to see what lesson we can learn.

E V A LU A T IO N O F RE C E N T PROGRAM M ES

In both Costa R ica and Tunisia the o rig in a l experim enta l area was quite la rge , but in each case, a fter 1 o r 2 y ea rs , it was reduced to a s ize that could be adequately overflooded with the available s te r ile m ed flies . A fte r the experim ent had been ca rr ied out the o rig in a l estim ates on the resou rces needed to handle the experim ental areas w ere seen to be unrea listic . Unfortu­nately, methods do not ex ist at present fo r obtaining in advance com plete ly re a lis t ic estim ates of what is needed to im plem ent such la rg e -s ca le p ro ­gram m es. Even a success with the technique in a sm all area does not n ecessa r ily provide the in form ation requ ired to set up a la rg e -s ca le test.Such d ifficu lties cause some c r it ic s to say that the SIT is not practica l. H ow ever, I do b e lieve that the method is p ractica l and that it can be used e ffic ien tly when rea r in g and re lea se techniques are co rrec t and eco log ica l

IAEA-PL-582/1 5

conditions are right. In the case of s te r ile - in sec t re lea se p ro jects in Costa R ica and Tunisia, the rea rin g program m es w ere e ffec tive a fter some m inor prob lem s w ere worked out; much cred it fo r this is due the labora tory p e r ­sonnel who w ere enthusiastic and carefu l; also, it is com parative ly easy to check that rea red insects are developing w ell. The question of the right re lea se techniques and the resu lting data (trap re c o v e r ie s and fru it sam pling) is not as easy to check. S im ila rly , eco log ica l conditions that depend on the co-operation of la rge numbers of people (lik e san itary m easures) are d if f i­cult to pred ict or ach ieve in any such la rg e -s ca le tests.

The successes in Costa R ica and Tunisia w ere lim ited in both duration and scope. H ow ever, the experiences g rea tly aided the developm ent of the SIT. We must obtain such base-lin e in form ation befo re we can proceed to the next le v e l of the developm ent process; we must p ro fit from past m is ­takes; and we must use a ll the data obtained in planning subsequent la rg e - sca le tests.

RECOM M ENDATIONS AND FU TU R E RESEARCH

Obviously, la rg e -s ca le tests of the SIT are expensive, and favourable resu lts cannot be guaranteed. H ow ever, chem ical treatm ents fo r pest control fa i l too som etim es — perhaps because of ra in fa ll, incom plete coverage, drift, o r insect res istance. T o co rrec t fo r d ifficu lties o f this type, we try to co-ord inate treatm ents with the optimum weather conditions, g ive better coverage of the crop, o r reduce retreatm ent in terva ls . F a ilu res with p es ti­cides are th ere fo re accepted and not usually attributed to the method — like they are with the SIT. L ik ew ise , fa ilu res with re leased parasites and predators are accepted on the basis that a good system o f evaluating and m axim izing th e ir e ffec tiven ess has not yet been developed; the SIT d eserves s im ila r forbearance.

To develop the system n ecessary to succeed with the SIT, we should co-ord inate our e ffo rts , we should share in form ation , and we should m in i­m ize duplication of e ffo rt. A lso , we must recogn ize that in sm a ll-sca le tests with s te r ile m ed flies , we can control the program m e and study a ll n ecessary param eters. In the la rg e -s ca le tests , we cannot control e v e ry detail, and we can m onitor only the most im portant param eters. A lso , it seem s that when the s ize of the re lea se area doubles, the resou rces needed apparently quadruple. A m a jor area of future research w ill th ere fo re invo lve the determ ination of the re a lly essen tia l param eters fo r a given .test. We know that they v a ry with the location and test conditions. In Hawaii, the choice of test s ite is not sim ple, and pretreatm ent to suppress the native f ly population is n ecessary . A lso , the average population le v e l is high and the clim ate is favourab le fo r the m ed fly so success is d ifficu lt in Hawaii. How­eve r , even i f we do not have the most favourable c lim atic conditions in Hawaii and do have many favourable inaccessib le areas in which the fru it f l ie s breed , we s t i l l have areas where we can conduct la rg e -s ca le tests with s te r ile re lea ses alone or in combination with poison baits and m ale- annihilation treatm ents.

N everth e less , we have not made su fficient studies of the eco log ica l relationsh ip between fru it f l ie s and other insect fauna in the environment.F o r exam ple, as noted, the ecosystem in Hawaii is ch aracterized by a clim ate that is favourable fo r fru it f l ie s but not particu la rly favourable fo r dependable con tro l operations, and topographic conditions that make access d ifficu lt

6 HARRIS

to many areas. How ever, on T in ian in the M ariana Islands, where the e co ­system is s im p ler than on Hawaii, the m elon f ly disappeared in 196 3 despite apparently favourable conditions; we do not know why. Since we should im plem ent s te r ile fru it f ly re lea se program m es when natural factors are exertin g the ir maximum suppressive e ffects on the native f ly population, we must know when these fa c to rs are exertin g th e ir maximum effects .

In Is ra e l, Tunisia, M orocco, and probably A lg e r ia , the clim ate in the c itru s-grow in g areas is such that the crop must be protected in sum m er and fa l l to reduce damage to the fru it from fem a les and from larvae; and such protection is by chem ical means. As a resu lt, in contrast, in Tunisia, the m ed fly prob lem is particu la rly severe in those locations where fru its that mature at various seasons o f the year are grown near citrus; a lso the land area used in citrus production is sm a lle r, and there is m ore intensive cultivation of this land, which aggravates the problem . (When citrus is grown in la rge pure and iso la ted stands, the m ed fly problem is less s eve re .) Bait sprays, the im m ed ia te ly e ffec tive method, and the SIT, the long-term , long-lasting, e ffec tive method, m ay th ere fo re be compatible in Tunisia and these other countries but p r io r ity must be given to m eeting im m ediate needs.

In addition, the SIT m ay not work against a ll fru it f ly species or even against the same species in a ll the areas of the w orld in which they are found. Th is is e sp ec ia lly true i f a system of reducing populations to a manageable le v e l and i f a ccess ib ility to a ll favourable eco log ica l niches are not possible.

F in a lly , in m y opinion, p r io r ity should be g iven to the development of pherom ones, fem ale lu res, and a m ore e ffic ien t method of m onitoring popu­lation trends and m ale annihilation of the m edfly. Such attractants are spec ific and could be applied with conventional spray or specia l equipment in combination with the SIT; they would a lso have a m inimum polluting e ffec t on the ecosystem and would perm it the use of s te r ile f l ie s to mop up pockets of su rv ivo rs le ft by the attractants. The fru it f ly parasites could be mass rea red and re leased separa te ly o r sim ultaneously with s te r ile fru it f ly re leases . Th is approach m ay function better in Hawaii and Central A m erica than in Europe.

In closing, I lis t fo r consideration the fo llow ing w ork as worthy of further e ffo r t in a co -opera tive program m e.

1. D evelop methods of determ in ing the essen tia l e co lo g ica l param eters that a ffect fru it f ly populations. Rem ote sensing m ay be used to determ ine plant host identity, density, and distribution, and computer population m odels may be used to p red ict serious outbreaks.

2. D evelop techniques to in tegrate chem ical and cultural control methods with the SIT. N on -p re fe rred hosts fo r human consumption m ay be used as trap crops in a cultural control to co llect and destroy fru it f l ie s during unfavourable periods.

3. Conduct co-ord inated research to avoid duplication of e ffo rt and acce lera te developm ent of (a ) quality control techniques, (b) s te r ile re lease methods, (c ) strain developm ent, (d) assessm ent of s te r ile re lea se e ffec ts , and (e ) assessm ent of s te r ile f ly behaviour in com parison with w ild flie s .

4. Determ ine when and how to apply in tegrated control (pherom ones, fem ale lu res, and m ale-annih ilation treatm ents) in combination with the s te r ile - in sec t technique.

5. D evelop methods of re leas in g fru it f lie s s te r iliz ed with chem osterilants.6 . Develop methods of m ass rea r in g and re leas in g fru it f ly parasites.

IAEA-PL-582/1 7

R E F E R E N C E S

BAUMHOVER, A.H., GRAHAM, A.J., BITTER, B.A., HOPKINS, D.E., NEW, W.D., DUDLEY, F.H.,BUSHLAND, R.C. (1955), Screw-worm control through releases of sterilized Üies, J. Econ. Entomol. 48, p. 462.

CHEIKH, М., HOWELL, J.F., BENSALAH, H ., HARRIS, E.J., SORIA, F. (1975), Suppression of the Mediterraneanfruit fly in Tunisia with released sterile insects, J. Econ. Entomol. 6, p. 237.

DE MURTAS, I.D., CIRIO, U., GUERRIERI, G., ENKERLIN-S., D. (1970), "An experiment to control Medi­terranean fruit fly on the island of Procida by the sterile-insect technique", Sterile-Male Technique for Control of Fruit Flies (Proc. Panel Vienna, 1969), IAEA, Vienna, p. 59.

HUFFAKER, C.B. (1971), Biological Control, Plenum Press, New York and London.

KNIPLING, E. (1955), Possibilities of insect control or eradication through use of sexually sterile males, J. Econ.Entomol. 48 , p. 459.

LaBRECQUE, G.C., KELLER, J.C. (Eds), (1965), Advances in Insect Population Control by the Sterile-Male Technique, Tech. Reports Series No. 44, IAEA, Vienna.

LOPEZ-D., F. (1970), "Sterile-male technique for eradication of the Mexican and Caribbean fruit flies: review of current status", Sterile-Male Technique for Control of Fruit Flies (Proc. Panel Vienna, 1969), IAEA,Vienna, p. 111.

MELLADO, L., NADEL, D.J., ARROYO, М., JIMENEZ, A. (1970), "Mediterranean fruit fly suppression experi­ment on the Spanish Mainland in 1969", Sterile-Male Technique for Control of Fruit Flies (Proc. Panel Vienna, 1969), IAEA, Vienna, p. 91.

MONRO, J. (1965), "Experimental control of Dacus tryoni" , Advances in Insect Population Control by the Sterile-Male Technique (LaBRECQUE, G.C., KELLER, J.C., Eds), Tech. Reports Series No. 44, IAEA,Vienna, p.22.

RHODE, R.H., SIMON, J., PERDOMO, A ., GUTIERREZ, j . , DOWLING, C.F., Jr., LINDQUIST, D.A. (1971), Application of the sterile-insect release technique in Mediterranean fruit fly suppression, J. Econ. Entomol. 64, p. 708.

SHAW, J.G., SANCHEZ RIVIELLO, M. (1965), Effectiveness of tepa-sterilized Mexican fruit flies released in a mango grove, J. Econ. Entomol. 58, p. 26.

STEINER, L.F. (1969), Control and eradication of fruit flies in citrus, Proc. First Int. Citrus Symp. 2, p.881.

STEINER, L.F., ROHWER, G.G., AYERS, E.L., CHRISTENSON, L.D. (1961), The role of attractants in the recent Mediterranean fruit fly eradication program in Florida, J. Econ. Entomol. 54, p. 30.

STEINER, L.F., MITCHELL, W.C., BAUMHOVER, A.H. (1962), Progress of fruit fly control by irradiation sterilization inHawaiiand the Mariana Islands, Int. J. Appl. Radiat. Isotopes 13, p. 427.

STEINER, L.F., HARRIS, E.J., MITCHELL, W.C., FUJIMOTO, M.S., CHRISTENSON, L.D. (1965), Melon fly eradication by overflooding with sterile flies, J. Econ. Entomol. 58, p. 519.

STERN, V.M., SMITH, R.F., VAN DEN BOSCH, R., HAGEN, K.S. (1959), The integration of chemical and biological control of the spotted alfalfa aphid. The integrated control concept, Hilgardia 29, p. 81.

IAEA-PL-582/2

GENETIC VARIATION IN NATURAL INSECT POPULATIONS AND ITS BEARING ON MASS -REARING PROGRAMMES

G. L. BUSH University o f Texas,Austin, Texas,United States o f America

Abstract

GENETIC VARIATION IN NATURAL INSECT POPULATIONS AND ITS BEARING ON MASS-REARING PROGRAMMES.

A new approach using gel electrophoresis o f genetically variable enzymatic and non-enzymatic proteins (allozymes) which can be used to monitor laboratory populations for genetic changes is discussed. Examples o f genetic alterations in laboratory strains o f the codling moth and screw-worm fly are presented. The results o f a survey o f genetic variation in the European cherry fruit fly are compared with the codling moth. The technique is very sensitive to environmental change, and offers a simple, rapid method of quality control.

The success of any sterile male release program is obviously predicated on the ability of factory produced insects to locate and mate with their wild counterparts. Because mating behavior in insects consists primarily of fixed action patterns which are under tight genetic control, artificial selection under laboratory conditions can and frequently does produce striking behavioral changes in a few generations [6 ]. Regrettably, this important fact is too often given a great deal of lip service but ignored or relegated to a back burner in the development of mass rearing and production line tech­niques.

Quantity rather than quality has generally been the measure of success in most mass rearing programs. Quality control programs that actually test for the performance of the insect under field conditions are almost non-ex- istent. This approach has led to some rather disastrous consequences as witnessed in the recent collapse of the screw-worm (Cochliomyia hominivorax) suppression and eradication program along the U.S.A. - Mexico border [5].

There are at least three reasons why effective quality control programs have not been incorporated into mass rearing programs like that of the screw- worm fly. First, until recently few individuals associated with mass rearing programs realized or appreciated the evolutionary implications and potential genetic pitfalls of adapting wild insects to the artificial conditions as­sociated with factory production. Second, little is actually known about the critical features of reproductive behavior and ecology of our insect pests which is essential for the development of meaningful quality control techniques. Finally, we have only meager information about the genetic structure of natural insect pest populations and the behavioral and ecological genetics of specific traits involved in mating behavior in the field.

If we accept the premise that one important goal of any mass rearing program is to maintain the correct combination of allelic forms at loci essential for normal mating behavior, we are faced with the problem of how this can be accomplished when basic behavioral and ecological data as well as vital genetic information on the species in question is usually non-existent.

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The screw-worm offers a good example of the problems facing most mass rearing programs developing effective quality control programs. Essentially nothing is known about the mating behavior of this diurnal fly in nature.Because no one has ever seen this species mating in the field and essential information on its ecology is lacking, no technique is available to monitor the production line flies for genetic changes affecting behavior.

The fact that the males have larger eyes than females and emit a pheromone[7] indicates that both visual and chemical cues are important in mating be­havior. Yet in factory reared flies used for release last year (APHIS Regular Production Strain) at least three recessive eye color mutants occurred at a frequency of about .01 percent. In Drosophila these homozygous mutant forms are partially or completely blind [8 ] and, more importantly, individuals hetero­zygous for color mutations are generally less fit than wild flies [6 ]. In the screw-worm production flies approximately 2 % of the flies are heterozygous for these visible subvital or sublethal alleles. More subtle deleterious mutations are also likely to be present in the lab population, but without adequate methods for estimating fitness their effects can not be established.

In addition, certain laboratory strains are known to differ in the female’s response to male pheromone. Females of the Mexican Strain do not respond to Florida Strain male pheromone [8 ]. The response of wild females to laboratory strain male pheromone has not been tested, but if flies with aberrant pheromones are produced, the effectiveness of the production line flies would be further reduced.

Difficulty has also been encountered in getting wild screw-worm flies to oviposit and mate under laboratory conditions [11]. The solution to this problem in the past has usually been to use the few flies that mate underartificial conditions as progenators of the next generation. After five orsix generations "normal” fertility and fecundity is restored. However, these "normal" flies are the very ones that are most likely to be genetically aber­rant and may be useless for release purposes.

A look at the methods used in mass rearing screw-worms suggests why gen­etically aberrant individuals exist in the production line flies. Until recently adults were held in total darkness to permit crowding and thus reduce rearing costs. Flies usually walked rather than flew to their food source and the oviposition device. Visual and odor cues were relatively unimportant for survival in this en­vironment and the selective advantage was conferred on those flies with genotypes that permitted them to mate and oviposit in the dark under crowded conditions.A blind fly is not at a disadvantage in such a colony as has been demonstratedin experiments with blind Drosophila reared in the dark with normal flies [9].

It is not surprising, therefore, that the mating success of the mass reared flies has deteriorated. Because artificial conditions are common to most insect mass rearing facilities, including those used in rearing such species as Dacus oleae and Ceratitis capitata, similar reductions in competitiveness are inevitable unless guarded against.

Some means must therefore be developed to ensure that genetic changes do not occur during laboratory adaptation. Before suitable bioassay techniques can be introduced we must know how much genetic variation occurs naturally at many different critical loci, and how fast and what kind of genetic alterations occur during domestication. Furthermore, we must know how important these changes may be to the competitive success of laboratory reared insects in the field.

Flight mill studies, mating speed, preference and propensity tests, startle reactions and several other methods (see Chambers, this Panel) have been proposed and studied as possible means of monitoring laboratory strains for behavioral changes. Because all of these measure some component

IAEA-PL-582/2 U

of behavior under completely abnormal conditions, it is difficult to establish if the results reflect normal behavior encountered in field conditions even when using wild flies for the test. Furthermore, it is almost impos­sible to obtain estimates of the total amount of genetic variability for any of these traits. Usually some form of a value judgment must be made as to what constitutes normal behavior.

There is one way to circumvent this problem through the use of gel electrophoresis of polymorphic enzymatic and non-enzymatic proteins (allozymes). This technique can be used to monitor the level of genetic variation at several loci in both natural and laboratory populations. It was first used with in­sects by Lewontin and Hubby [12] and is now widely applied to the study of pop­ulation genetics in several insect groups. A review of the technique as applied to several species of Tephritidae is available [4] along with a step-by-step outline of the methods employed [3].

Past work has dealt mostly with the genetic structure of wild populations, but recently I have adapted it for use in a mass-rearing quality control program for the screw-worm, codling moth, and a species of Tephritidae. Allozyme data can routinely be used to monitor laboratory strains for any indication of gen­etic shifts that might be going on at other loci which cannot be studied directly. We will look at the codling moth first.

In the codling moth (Laspeyresia pomonella) a genetic survey of 27 loci in natural and laboratory populations has revealed a pattern of variation typical of what one would expect in laboratory populations undergoing intense inbreeding and artificial selection (Bush,in preparation).

Figure 1 is a dendrogram of genetic distances that exist between various populations of codling moths. It was derived by an unweighted pair-group method of clustering developed by Sokal and Sneath [14], using generalized genetic dis­tances calculated on the basis of weighted protein mobility rates of five polymor­phic loci (PGM, EST-A, EST-C, ADH, AK-A). A copy of the program and summary of methods employed to calculate these distances, which were developed by Drs.P. Smouse and R. Richardson (Department of Zoology, University of Texas), can be obtained on request.

It is quite evident that all natural populations of the codling moth (those underlined in Fig. 1) share similar alleles and gene frequencies. Even the walnut and apple races, which are considered by some biologists to represent rather distinct non-interbreeding populations in California, show no statistically significant differences in gene frequency. Little or no correlation, however, is evident between the genetic structure of the laboratory reared populations and the localities from which they originated. This indicates that they have diverged genetically from the natural populations.

An analysis of genetic variability in natural vs. laboratory populations is also interesting (Tables I and II). At six polymorphic loci (PGM, PGI, EST-C,EST-A, ADH, and AK-A) the wild populations in Western North America on the average have 2.7 alleles per locus while the laboratory populations from the same regions (represented by an *) average only 2.43. This represents a loss of overall genetic heterozygosity and indicates that a certain amount of in- breeding or selection or a combination of both has occurred in the laboratory populations. This observation is further supported by the fact that of the loci sampled in laboratory populations, 12.5% were significantly deficient in heterozygotes indicating strong inbreeding. Of the loci sampled in the wild populations, only 2 (6.7%) lacked a sufficient number of heterozygotes.

A preliminary study of screw-worm flies gives very similar results al­though the data is not yet extensive. After a survey of 36 loci, the five most polymorphic loci were selected for analysis. Table III summarizes the

12 BUSH

FIG

. 1.

Gen

etic

di

stan

ce

betw

een

natu

ral

(und

erlin

ed)

and

labo

rato

ry

popu

latio

ns

of

the

codl

ing

mot

h.

IAEA-PL-582/2 13

T A B L E I. NUM BER OF A L L E L E S A T SIX LO C I PO LYM O R PH IC IN N A T U R A L PO PU LA T IO N S OF THE CODLING M OTHSamples sign ifican tly defic ien t in heterozygotes with c irc le s : those showing a surplus of heterozygotes with squares

Wild populations Number of alleles per locus Average

PGM EST-A EST-C ADH PGI AK-A

1 . Sunnyside, Wash, (ex. apple)

3 5 3 1 2 3 2.83

2 . Terrace Hts., Wash. (ex. apple)

3 5 2 i g o 2 2.50

3. Bodine Rch., Calif, (ex. plum)

4 © 3 1 2 2 2.83

4. Haines Rch., Calif, (ex. walnut)

3 3 3 1 2 2 2.33

5. Medford, Oregon (ex. pear)

© 5 3 1 2 2 3.00

Average 3.60 4.60 2.80 1 . 0 0 2 . 0 0 2 . 2 0 2.70

Loci with significant surplus of homozygotes = 6.7

findings. The number of alleles is not given as the genetics of each locus has not yet been established. There is evidence, however, that even in lab­oratory populations polymorphic for the same locus the alleles involved may be different. The level of differentiation between strains is therefore greater than indicated.

The APHIS Regular Production Strain and the Puerto Rican Strain are segregating only at the EST locus. The Regular Florida and NST Texas Strains are both segregating at the EST and a-GDH locus while the remaining four laboratory strains are segregating at other loci as well. We as yet have only a few samples of wild flies reared from individual egg masses col­lected on wounded animals. However, there is a strong indication that the wild flies are polymorphic at more loci and have more alleles per locus than do their laboratory reared counterparts. Because of the screw-worm*s ability to disperse long distances, [1 0 ], genetically homogeneous populations probably extend over broad regions with little genetic variation existing between widely separated localities.

Evidence of genetic changes in laboratory colonies is not yet available for any species of Tephritidae, but we do have extensive evidence on wild pop­ulations. The same methods were used to calculate the genetic distances as were used on the codling moth.

Recent investigation of genetic variation in four polymorphic loci in natural populations of Rhagoletis cerasi (Bush and Boiler, in preparation) has revealed that gene frequencies for this species do not vary substantially over its entire range. In R. cerasi no significant differences could be

14 BUSH

T A B L E II. NUM BER O F A L L E L E S A T SIX LO C I PO LYM O R PH IC IN LA B O R A TO R Y PO PU LA T IO N S OF THE CODLING MOTH Samples sign ificantly deficient in heterozygotes with c irc le s . Except w here noted a ll populations w ere rea red on a r t if ic ia l labora tory diets

Lab Populations Number of alleles per locus Average

PGM EST-A EST-C ADH PGI AK-A

1. Yakima, Wash.* 3 5 2 1 2 3 2.67

2 . Porterville, Cal.* 3 3 3 1 2 © 2.33

3. Oak Glen, Cal.* 3 © 3 1 2 2 2.33

4. Summerland, В. C.* (Apple)

3 © 3 1 2 © 2.50

5. Summerland, В. C.* 3 © 3 1 2 © 2.50

6 . Grand Junction, Colo. 5 © 2 2 2 2.83

7. Wadenswil, Switz. 4 3 2 1 2 2 2.33

8 . Darmstadt, Germ. © © 3 1 2 3 2.50

9. Mixed Switz. § Italian 3 2 2 1 2 3 2.16

1 0 . Basel, Switz. 2 3 2 1 2 3 2.16

1 1 . Kiev, USSR 3 3 2 1 2 3 2.33

1 2 . Mixed (4, 8-12 ) 4 3 2 1 2 3 2.50

Average

Loci with

3.30 3.25 2.42 1.08 2.00

significant surplus of homozygotes =

2.50

12.5%

2.43

^Samples compared in text with natural populations in Table I.

found even between the eastern and western populations of the cherry infesting race which show unidirectional sterility and probably represent distinct species or at least semi-species [2]. Furthermore, even when individuals of the most distant populations of R. cerasi (Spain, Italy, Turkey, the Netherlands, and Germany) are included in the analysis (Fig. 2), the genetic distances are about the same order of magnitude as exist between the wild codling moth populations in western North America.

These close similarities in the genetic structure over broad regions between reproductively isolated populations suggest that the frequency of alleles at each locus is being tightly held in an adaptive balance by natural selection. This lack of geographic variation at the allozyme level in insect populations has been encountered by several investigators [13] and appears to be related to the type of environmental heterogeneity (graininess) encountered by most insects.

IAEA-P L -582/2 15

T A B L E III. F IVE LOCI PO LYM O R PH IC IN A T LE A S T SOME LA B O R A TO R Y PO PU LA T IO N S OF TH E SCREW WORM F L YO ver 50 individuals w ere electrophoresed from each population rea red at the USDA Screw w orm R esearch Labora tory , M ission , Texas + = two o r m ore a lle le s present.

Adults Loci

LAP ALD PGM GDH EST

APHIS-Regulár Production +

PRN-F9-Puerto Rico Strain +

NTS-New Texas Strain + +

Regular Florida Strain + +

C3-F5-Texas Collection + + +

ADHIS-Old Mexico Strain + + +

C9-Fl-New Mexican Collection + + +

TX-F 8 -New Texas Strain + + +

It could be predicted therefore that any shift that might occur in lab­oratory populations of R. cerasi and other Tephritidae away from the normal genetic structure of wild populations would provide an excellent indication that selection is occurring in these laboratory colonies. Also, change at any of these loci during the process of colonization would indicate that shifts in gene frequencies might also be occurring at other key loci as well. Steps could then be taken to alter rearing methods in order to halt any further change and possibly to restore the population to its original state.

We are now developing a simplified sampling method and the computational tools to apply the allozyme polymorphism approach to a mass rearing monitoring system. This technique will not only provide an early warning system of gen­etic change, but will also furnish data on the rates at which these changes occur and give some indication of the levels of inbreeding that are going on in the laboratory population.

Because changes in allozyme frequency appear to be extremely sensitive to environmental change brought about by mass rearing techniques, they can offer a simple, rapid method of quality control. As with any existing method now in use, allozymes do not measure directly those genes that are affecting some critical phase of behavior. However, because they represent a direct measure of the genetic structure of the population they are probably a much better in­dicator of how effective mass rearing programs are in maintaining the natural genetic structure of the wild populations than some of the other techniques now in use. The allozyme method, particularly when used with other methods of qual­ity control, can reduce the çhance of selecting for unwanted genotypes that re­duce the effectiveness of laboratory reared flies and provide an early warning system that trouble may be ahead.

1 6 BUSH

Cer

asus

, LX

= Lo

nice

ra

xylo

steu

m.

IAEA-PL-582/2

I would like to express my gratitude to Ms. Mary Jane Andrews and Ms. Cynthia D. McWhorter for their technical assistance. I also thank the many North American and European colleagues whose ex­cellent cooperation in supplying samples for electrophoresis made this study possible. This work was supported by a grant from the National Institutes of General Medical Sciences, GM 15769.

R E F E R E N C E S

[1] ANONYMOUS, Cooperative Econ. Insect Rep. 23̂ , 155 (1973).

[I] BOLLER, E. F., BUSH, G. L. The population biology of the Europeancherry fruit fly, Rhagoletis cerasi L. (Diptera: Tephritidae)I. Evidence for genetic variation based on physiological parameters and hybridization experiments. Ent. exp. appl. (1974) In press.

[3] BUSH, G. L., HUETTEL, R. N. Starch gel electrophoresis of tephritidproteins. I.B.P. Working Group on Fruit Flies. Population Genetics Project Phase I. (1972).

[A] BUSH, G.L. Population and ecological genetics of fruit flies.In I.B.P. Synthesis Report on Fruit Flies (1973). In press.

[5] C.B.C., D.M.B. The screw-worm strikes back. Nature, Lond. 242(1973) 493-494.

[6 ] EWING, A. W., MANNING, A. The evolution and genetics of insectbehavior. Ann. Rev. Ent. 1¿ (1967) 471-494.

[7] FLETCHER, L . W., 0 1 GRADY, Jr. J.J., CLABORN, H.V., GRAHAM,O.H.A pheromone from male screw-worm flies. J. Econ. Ent. 5 9 _ (1966) 142-143.

[8 ] FLETCHER, L. W., CLABORN, H. V., TURNER, J. P.,LOPEZ, E.Differences in response of two strains of screw-worm flies to the male pheromone. J. Econ. Ent. 61̂ (1968) 1386-1388.

[9] GEER, B. W . , GREEN, М. M. Genotype, phenotype and mating behaviorof Drosophila melanogaster. Amer. Nat. 6 6 ̂ (1962)175-181.

[10] HIGHTOWER, B. G. ADAMS, A. L., ALLEY, D. A. Dispersal of releasedirradiated laboratory-reared screw-worm flies. J. Econ. Ent. 58

- (1965) 373-374.

[II] HIGHTOWER, B. G., 0 1 GRADY,Jr., J.J., GARCIA, J.J. Ovipositionalbehavior of wild-type and laboratory-adapted strains of screw-worm flies. Envirn. Ent. 1_ (1972) 227-229.

[12] LEWONTIN, R.C., HUBBY, J.L. A molecular approach to the studyof genetic heterozygosity in natural populations. II, Amount of variation and degree of heterozygosity in natural populations of Drosophila pseudoóbscura. Genetics .54 (1966) 595-609.

[13] SELANDER, R.K., KAUFMAN,D.W. Genetic variability and strategiesof adaptation in animals. Proc. Nat. Acad. Sci. USA Т Ц . (1973) 1875-1877.

[14] SOKAL, R.R., SNEATH, P.H.A. Principles of numerical taxonomy,W. H. Freeman. San Francisco. (1963).

A C K N O W L E D G E M E N T S

IAEA-PL-582/3

QUALITY IN MASS-PRODUCED INSECTS

Definition and evaluation

D .L . CHAMBERS

Insect Attractants, Behavior and Basic Biology Research L a b .,USDA, ARS,

Gainesville, Florida,United States o f America

Abstract

QUALITY IN MASS-PRODUCED INSECTS: DEFINITION AND EVALUATION.The insect that is mass-produced and released in a control programme is in effect a biological bullet,

a self-guided missile designed to deliver a beneficial effect against a pest insect. The ability o f the released insect to achieve this objective may be influenced in many ways. The control o f the quality o f mass- produced insects must include an understanding o f the behavioural components critical to their success and an evaluation of their performance based upon these behavioural components. The paper discusses some of the principles and techniques being used and developed to study behavioural performance and quality. Included are discussions o f tests of: vigour, irritability, activity, sound production, response thresholds, reproductive preference and drive, biotic potential, and others.

1. INTRO D UCTIO N

Th is paper is on the subject of insect behaviour as it re la tes to the con tro l of fru it flie s by the s te r ile re lea se method and on the quality o f m ass-produced insects. The in terest in this subject (it is a single subject) is burgeoning: a workshop was recen tly held at a Branch m eeting o f the E n tom olog ica l Society o f A m erica ; my agency, the A gricu ltu ra l R esearch Serv ice , w ill soon hold a pertinent workshop in G a inesville ; and m ost of the recen t panel m eetings o f O ILB , IB P , and IA E A have applied considerab le em phasis to or concentrated exc lu s ive ly on this subject. Apparen tly ento­m ologists have becom e aware that some o f the prob lem s encountered in pest con tro l through re lea se of m ass-produced insects, entomophagous or s te r iliz ed , may occur because o f behavioural d e fic ienc ies resu lting from lack o f con tro l of quality.

We intend to make the study o f p rincip les and p ractices in behavioural quality m easurem ent and management one o f the m a jor program m es at the Insect A ttractan ts, Behavior and Basic B io logy R esearch Labora tory of the A gr icu ltu ra l R esearch S erv ice , USDA. Thus, I intend, in these few pages, to outline some o f the philosophies and p ractices we w ill be using with a number of se lected species. Am ong these is the Caribbean fru it fly , Anastrepha suspensa ( Loe w ).

B efore em barking on my d iscussion, I would like to re fe r the reader to the rev iew o f the subject o f behaviour of m ass-rea red insects by Dr. E rnst B o ile r (1972). Because o f his thoroughness, there is much I need not re ite ra te here.

19

20 CHAMBERS

2. D EFIN ITIO NS

Quality can be defined as the re la tiv e degree o f exce llence in some tra it or sk ill that a thing possesses. Thus, when the term quality is applied to insects m ass-produced fo r re lea se in research or control program m es, it r e fe rs to the ab ility o f the re leased insects to p erfo rm their function and to p erfo rm re la tiv e to some standard. The standard is genera lly taken to be the insect its e lf in either its native or untreated condition (i.e . not irrad ia ted , not dyed, not se lected by stra in , e tc .); the function is described by the nature o f the con tro l p rogram m e being im posed, as, fo r exam ple, inducing s te r ility or m orta lity in the ta rget population. The ab ility to p e r ­fo rm the function r e fe rs herein to behavioural param eters (i.e . adaptedness, m otility , and reproductive success), which a re , u ltim ately , re flec tion s o f the genetic, physio logica l, and b iochem ical state o f the insect.

Because ab ility is tied to function in the analysis o f quality, "natu ra l­n ess" (lack o f deviation from the standard) is not n ecessa r ily the best m easure o f high quality. (P er fo rm an ce exceed ing the standard could be des irab le .) C on verse ly , se lection of one or a few function-related tra its as m easures o f o v e ra ll quality can be dangerously m islead ing if, unknown to the sc ien tist, other v ita l tra its are lacking. An im portant challenge is to identify and rank the im portance o f the behavioural tra its that contribute to the requ ired function of re leased insects.

3. STANDARDS

The entom ologist responsib le fo r con tro l of quality in insect m ass- production is , then, faced with two d ifficu lt decisions: ( 1 ) what is themost meaningful standard o f re fe ren ce ; and ( 2 ) what are the behavioural tra its that must be evaluated and how can they be m easured? Idea lly , one m easures the perform ance o f the expected function o f the insects them ­se lves and makes these decisions on the basis o f d irec t inform ation.These m easurem ents may be feas ib le in con tro l p rogram m es where it is b io lo g ica lly possib le to m onitor resu lts concurrently with re lea ses , as in s te r ile m ale re lea ses against m osquitoes where egg ra fts can be co llected and the le v e l o f s te r ility induced in the native population thus measured d irec tly (Weidhaas et al. (1972)). S im ila rly , the percentage o f parasitism occu rrin g in a pest insect population may be m onitored while parasite re lea ses are underway. In these cases, the standard is the ta rget insect population, the function is inducing suppression, and the m easurem ent is the degree o f success.

H ow ever, re lian ce upon the philosophy that "su ccess is the best m easure" is unacceptably risky in p rogram m es such as s te r ile re leases fo r fru it f ly con tro l where d irec t m easurem ent o f behavioural ab ility (inducing s te r ility ) cannot be read ily m easured (here I mean la rg e -s ca le tests or con tro l p rogram m es; egg fe r t i l ity in fie ld cages can be determ ined). In such program m es the usual c r ite r ion o f success is population suppression or erad ication , a resu lt delayed by at least one reproductive cyc le from the re lea ses . Thus, by the tim e you know you are fa iling , based on popula­tion data, it may be too late to make co rrection s.

Hence, we must often develop standards and m easurem ents fo r ind irect m onitoring, assum ing thereby that we can se lec t behavioural tra its rep re -

IAEA-PL-582/3 21

sentative of ab ility to ach ieve the function and that we can equate ab ility in these tra its to the likelihood o f ach ieving the ob jective. (The r isk in these assumptions may a lso be la rg e .)

Often there is lit t le choice in the se lection o f standards. The re leased s te r ile fru it f ly m ost des irab ly reta ins those behavioural tra its that are n ecessary for com petition with its native counterpart. Thus, the native f ly is the m ost approp­ria te standard. H ow ever, it is exceptionally d ifficu lt to design and conduct tests that adequately com pare stock (m ass -rea red ) and native insects without bias in favour o f one or the other: quantitative fie ld data fo r spec ific behavioural tra its are d ifficu lt to obtain and in terpret; con verse ly , confinement o f native fl ie s 'in test cages n ecessa r ily a lters th e ir behaviour. Because of these d ifficu lties , we a re often fo rced to use an in ternal standard. F o r exam ple, in a test of radiation effects we may com pare an unirradiated stock fly with an irrad ia ted stock fly . Such internal standards are not n ecessa r ily a poor com prom ise as long as the ob jective o f the com parison is m easurem ent o f change in stock quality and no im m ediate re fe ren ce to the native f ly is assumed or intended. M oreove r, acceptance o f this com prom ise allows one to proceed with selection and use o f a number o f techniques fo r studying com parative behaviour in the labora tory and in cages. F rom these studies, su ffic ien t insight may develop to perm it se lection and in terpretation of one or o f a few labora tory and fie ld tests w herein the native fly population provides a s t ill m ore meaningful standard. H ow ever, labora tory com parisons o f stock and native flie s should be conducted under conditions that extract maximum perform ance fro m native f lie s , not the re v e rs e (which is often the case).

j

4. M EASUREM ENTS .

iThe second decision I mentioned r e fe r re d to the se lection and m easu re­ment o f sk ills fo r evaluating fly quality. I wish to em phasize v e ry strongly that when one devises, applies, and in terprets labora tory or fie ld cage behaviour one must include the resu lts o f studies o f the behaviour o f native f lie s in the fie ld . Such studies must be o f su ffic ien t depth to indicate those behavioural components that w ill be v ita l to the success o f the re leased insect and thus m ost meaningful fo r m easurem ent. That is not to say that a ll natural behavioural components w ill be necessary to the achievem ent o f the ob jective fo r which the insects are re leased or, con verse ly , that on ly,tests o f v ita l functions are meaningful in m easuring changes in stock quality. Adequate knowledge is requ ired o f both natural behaviour and program m e function so su fficien t p r io r ity and knowledgeable attention can be given to con tro l of s ign ificant param eters of quality.

The principa l des ired function o f re leased s te r ile flie s is mating and this behavioural tra it is often se lected fo r m easurem ent; indeed, it is som etim es the sole measurement.. To c la r ify my point I present the data in Tab le I which appeared in a recen t publication by K e is e r et al. (1973) concerning fru it f ly mating behaviour.

It is quite c lea r that treatm ents В, С and D had no e ffec t on mating success as com pared with the con tro l (A ). H ow ever, had these data been developed as part o f an assessm ent of fly quality (which is not the case) it would be dangerous to assume that this m easurem ent would be valid fo r o v e ra ll perform ance in a re lea se program m e because the treatm ents

22 CHAMBERS

T A B L E I . E F F E C T O F T R E A T M E N T O N M A T I N G S U C C E S S

Oriental fruit flies

Melon flies

Treatment No.

eggsdeposited

HatchNo.

eggsdeposited

Hatchm

A 249 62 180 94

В 581 66 360 93

С 332 78 120 93

D 346 67 240 94

consisted o f to ta l rem ova l of one (C ,D ) o r both (B ) wings from the m ale.This is a de libera te overstatem ent of my point, and I use data gathered in a test that was not conducted in a manner quite like that o f the usual m ating test, the ra tio test. N everth e less , the analogy is c lose enough to va lidate my position, which is that ra tio tests or s im ila r mating tests, though assumed to g ive an ove ra ll v iew o f perform ance o f fl ie s prepared fo r s te r ile re lea se , are in sm all cage conditions actually only m easurem ents o f copulation. The fact is that behavioural tra it probably has the low est threshold of any mating tra it, is one o f the hardest to a ffect, and is , thus, one o f the least sensitive to m easurem ent. It is the prim e and fina l tra it in a chain of behavioural tra its that could be weakened in e a r lie r links and not be detected in a test o f term ina l function.

I b e lieve that it is necessary to routinely evaluate the perform ance of fl ie s produced and treated fo r re lea se in each o f the three m a jor behavioural param eters that are functionally necessary — adaptedness, m otility , and reproductive success. I further be lieve that se lection o f appropriate tests o f these param eters can only fo llow ( 1 ) a fa ir ly thorough study of the behaviour of the fly , ( 2 ) determ ination (perhaps sub jective) o f potential key behaviour tra its , and at least p re lim in ary estim ates o f which tra its are subject to a lteration through treatm ent o r selection , (3) development o f techniques fo r m easuring those tra its , and (4) acceptance of perform ance le v e ls fo r those tra its .

M easuring adaptedness

The meaning I intend fo r the param eter adaptedness includes such concepts as b io log ica l fitn ess, behavioural con form ity , and genetic s im ila r ity . It is a m ore genera l ca tegory than m otility o r reproductive success and covers many possib le behavioural tra its , some o f which are im portant to these other two ca tegories . Thus, production or perception o f pheromones may be im portant in reproduction, and orientation to appropriate hosts may be important in m otility (d istribu tion ). H ow ever, there are some genera l tests that can identify changes in adaptedness and would thus signal that sp ec ific behavioural param eters need to be tested.

IAEA-PL-582/3 23

Dr. Bush discusses in these panel proceedings one of the m ost prom inent and usefu l o f these — survey o f genetic content by enzym e analysis. This is a m ost usefu l too l fo r testing the h ighly im portant aspect o f genetic h etero ­geneity and d ivergence, as Dr. Bush has demonstrated.

Other physio log ica l tests can a le rt one to changes in adaptedness.Some o f these are: tests fo r changes in pestic ide res istance; changes in m etabolic function, such as C 0 2 output, nutritional needs, o r re s e rv e content; changes in to lerance to tem perature, irrad ia tion , or other physical factors ; changes in fe r t i l ity , fecundity, longevity , or population s tress to lerance; and changes in b io log ica l con form ity such as rhythm icity, mating behaviour, host sp ec ific ity , or chem ica l and physical cue production or recogn ition . Many others could a lso be proposed. The a rtic le by Langley (1970) indicates certa in physio log ica l param eters that could indicate adaptive shifts in rea red populations.

Some o f the techniques fo r studying insect behaviour that we are deve lop ­ing and evaluating in our labora tory are useful fo r m easuring adaptedness.D r. M ilton Huettel is applying the technique o f enzym e analysis described by D r. Bush to prob lem s of variations in labora tory stocks and native strains o f s e v e ra l insect species including Anastrepha suspensa. A lso ,Dr. W illiam K. Tu rner, an agricu ltu ra l engineer on our sta ff, is developing sensitive techniques fo r m onitoring re sp ira to ry functions o f insects fo r the study o f insect response to radiation (Tu rn er and Charity (1971), Turner et al. (1973)). These procedures should have ready application to the d e te r­mination o f adaptive shifts in insect behaviour.

Dr. J.C. Webb, co llaborating with D r. John Sharp and with m e, has been studying sound production and perception in A . suspensa (and other insects); Dr. Webb has developed an exceptional a rray of equipment fo r the study of insect sound, including a la rge anechoic chamber with con­tro lled c lim atic conditions and e lectron ic equipment fo r record ing, analysing, and reproducing sounds. F igu re 1 displays the sound prints

F R E Q U E N C Y - К H £

FIG .l. Sound frequency signatures o f male A . suspensa displaying the following behavioural traits: flight; signalling; premating (after mounting the female but before copulation); and aggression (attempted territorial competition).

24 CHAMBERS

T A B L E II. AN A LYS IS OF F L IG H T SOUND FREQUENCIES OF Anastrepha suspensa

Age(days)

TreatmentPower output

(dB) in first fundamental

Power output (dB) in

harmonics

No.of harmonics

1 A 10.4 40.1 7

В 15.01 56.1 8

2 A 11.4 38.7 7

В 13.0 70.5 11

3 A 8.7 45.3 8

В 16.0 53.0 9

a Abnormal flies; В = flies detrimentally affected in shipment.

ch aracteris tic o f four behavioural activ ities o f A. suspensa — fligh t, m ale signalling, prem ating, and a ggress ive behaviour (Webb (1973)). We be lieve it w ill be possib le to m onitor the sounds produced by a sample of a popula­tion rea red and treated for re lease and thereby to determ ine both the quantity and quality o f the activ ity of that population. In other words, the quality and re la tiv e distribution and rhythm icity o f behaviour such as restin g , fly in g , aggression , mating, ca lling, etc ., can be determ ined by evaluation o f the sounds produced.

Tab le II shows the fligh t sound analysis o f two batches o f A . suspensa, one considered to be norm al and one suspected o f having su ffered d e tr i­m entally from shipping conditions. (We gra te fu lly acknowledge the p rovis ion o f test insects by Dr. R ichard Baranowski, U n ivers ity o f F lo rida ,Hom estead, F lo r id a ).

Note that the presum ably abnormal flie s not only produced m ore sound power in the f ir s t fundamental frequency but also m ore in both number of harm onics and power in harm onics. We ten tatively in terpret this as the resu lt of ir re gu la r and/or unsynchronized wing m ovem ents. Other exam ples o f sound analysis are discussed la ter.

M easuring m otility

The ab ility o f the re leased s te r ile f ly to v igorou s ly in sert its e lf into the habitat o f the native pest insect has always been recogn ized as of prim e im portance. Stock flie s subjected to treatm ents such as irrad ia tion , dyes, packaging, and shipping have been noted to be re la t iv e ly sedentary. A number o f tests o f m otive behaviour have th ere fo re been developed. They can be conveniently divided into two ca tegories: ( 1 ) m easurem ents o f capability (v igou r, strength, v e lo c ity , endurance, e tc .); and ( 2 ) m easurem ents o f propensity (w illin gness, d r iv e , threshold, e tc .).

R esearch to date has concentrated p r im a r ily on fligh t capability.A number o f us present at this panel have conducted fligh t m ill studies with fru it f l ie s , and fie ld re lea se -recap tu re data are frequently reported .

IAEA -PL-582/3 2 5

FIG.2. Relationships of fly age and frequencies o f wing beats o f male and female A_. suspensa suspended without tarsal contact over a microphone, thus wing movement without lateral motion (static flight).

FIG.3. Flight velocity and frequencies o f wing beats o f male and female A. suspensa suspended from a flight mill rotor and passing over a microphone during lateral flight (dynamic flight).

I b e lieve such tests are ex trem ely im portant to quality testing. The fligh t m ill system at the G a in esv ille labora tory w ill be used to evaluate the fligh t capability in A . suspensa; at present it is occupied in tests with other insects. This system , in its ro to r design, is essen tia lly like that o f Schoenleber et al. (1970), though the design was suggested to me independently by an instrument m aker in Honolulu. Dr. B o ile r a lso uses a s im ila r system .In our fligh t m ill, rotation o f the arm interrupts a light beam to a photo­tran s is to r, and this signal is transduced v ia an event re co rd e r onto a tape record in g that is analysed by a com puter. H ow ever, a d ig ita l o r s trip chart record in g can also g ive valuable data.

Another m easurem ent o f m otive ab ility is wingbeat frequency. F igu re 2 shows the wingbeat frequencies o f m ale and fem ale _A. suspensa as a function o f age. The data w ere developed by Dr. Webb (1973) by sound analysis.

26 CHAMBERS

£■О»

é

FIG.4. Aciographic equipment for measuring activity patterns and vigour: above - insect cages suspended in a frame on rubber bands; lower left - vibration detector mounted on top o f a single cage; lower right — circuitry and recording equipment for transducing vibrations onto strip-chart recordings.

IAEA-PL-582/3 27

Frequency was s im ila r fo r both sexes and increased until the flie s w ere about 1 2 days old, then it decreased s ligh tly until wing fray ing evidently produced further in creases. Sharp (1972) showed how stroboscop ic m easu re­ment o f wingbeat frequency can indicate irrad ia tion e ffec ts . In our m ore recen t tests , sound analysis coupled with the fligh t m ill allowed simultaneous m easurem ent o f w ingbeat frequency and fligh t v e lo c ity and showed the lin ear relationsh ip (Webb (1973)) (F ig .3 ). I would a lso like to suggest that inexpensive and uncom plicated tests that indicate m otive capability can be devised. F o r exam ple, rate o r frequency o f fligh t across a darkened room to a lighted window can provide a m easure o f fligh t ability.

It is my opinion that fligh t propensity may be a behavioural tra it that is equally o r m ore im portant than fligh t capability in the success of a s te r ile re lea se program m e. The in itia l d istribution of the re leased flie s can cover the in fested areas, but the flie s must a g g ress iv e ly search out the proper habitats and locate mates. In fact, low m otive propensity has been suspected as a reason fo r lack of success in se ve ra l fly re lease p rogram m es. A test fo r m otive propensity is th ere fo re im portant, and I r e fe r the reader to two sim ple methods of obtaining this m easurem ent. Schroeder et al. (197 3b) described an inexpensive technique fo r m easuring fligh t propensity. W ith this unit we have shown that irrad ia ted stock M editerranean fru it flie s w ere approxim ately 50% less prone to fligh t than unirradiated or native flie s . In addition, we a lso use at our labora tory an actographic device developed by Dr. Norm an Leppla , based on his o rig in a l design (Lepp la and Spangler (1971)). Banks o f screen cages suspended on rubber bands a re fitted individually with s ilica chip transducers (m icrophone- type pickup d ev ices ) that a re inexpensive detectors o f v ibrations. The m ovem ents o f insects against the cage walls a re detected and recorded (F ig .4). Since both amplitude and frequency are recorded , the system provides m easurem ents o f the frequency and vigour o f movem ent as w ell as indicating circad ian ch a racteris tics . (A s mentioned e a r lie r , sound analysis can a lso indicate the kind and quality o f movem ent in a cage of f lie s .)

Much valuable in form ation concerning fligh t behaviour in the fie ld can be obtained, and many publications describe methods o f conducting such fie ld studies. A good re fe ren ce source is the a rtic le by Bateman (1972).A lso , Dr. Prokopy (1975) has presented the resu lts o f novel and potentially useful new techniques fo r fie ld studies of fru it f ly movem ent. A t the Attractants and Behavior Labora tory , we have an active program m e of developing and using techniques fo r studying insect m ovem ent in the fie ld (at present, insects other than fru it f lie s ). Thus, my concentration in this b r ie f paper on our laboratory data should not im p ly that we are neglecting the im portant fie ld studies.

M easuring reproductive success

B o ile r (1972) presented a thorough discussion o f prem ating and post­m ating mechanism s that m ay resu lt in reproductive fa ilu re in re leased insects. I w il l use these same d iv is ions to discuss some of the behavioural tra its that a re probably needed in re leased s te r ile fru it f l ie s and som e o f the tests used to evaluate perform ance of spec ific behavioural tra its . The typ ica l ra tio test I b e lieve spans both p re- and postm ating param eters

28 CHAMBERS

(without identify ing wherein fa ilu re m ight lie but se rv in g as a screen fo r both a reas ). See F r ied (1971) fo r a com prehensive discussion o f ra tio test analysis.

In the f ir s t ca tegory , no mating occurs.

A . Poten tia l mates do not meeta. spatial d islocationb. a ltered p eriod ic ity o f mating activ ityc. communication fa ilu red. d iscon form ity o f physio log ica l state o r age

B. Poten tia l mates m eet but do not matea. com m unication fa ilu reh. physio log ica l d iscon form ity c. com petitive displacem ent

In the second ca tegory , a s te r ile mating takes p lace, but the mated fem ale is not rem oved from the reproducing population.

C. Copulation occurs but subsequent m ating with a fe r t i le m ale resu lts in fem ale fe r t ility .

D. Copulation occurs but the s te r ile mating does not induce re jec tion of subsequent m ales in the native fem ale.

T estin g prem ating factors

E thologica l iso lation is probably best observed in the fie ld (P rokopy (1968)) o r in la rge fie ld cages (K a tiya r and R am irez (1970); Holbrook and Fu jim oto (1970); Ohinata et al. (1971)). Thus, it has been possib le to observe a ltered period ic ity , s ize and strain p re feren ce , s ite p re feren ce and com petitive displacem ent. Spatial d islocation can be d iscovered through ca re fu l fie ld observations. D iscon form ity o f physio log ica l state or age m ight be suspected when cage tests indicate mating success but fie ld data do not; then su rv iva l factors (inadequate longev ity ), e a r ly re lea se , or retarded maturation through treatm ent o r handling would be suspected (s e e Haniotakis (1973)). H ow ever, laboratory tests of behavioural con form ity are certa in ly possib le. Schroeder et al. (197 3a) demonstrated in uniquely s im ple labora tory tests that gamma irrad ia tion o f D. cucurbitae as pupae delayed sexual maturation 24 hours and reduced mating intensity, but la rge cage tests w ere requ ired to determ ine that tim e o f mating was not a ltered .

Communication fa ilu re is an aspect o f behaviour that in terests us at our laboratory . Dr. Webb, D r. Sharp and I have developed p re lim in ary data on the s igna lling sound produced by m ale A . suspensa and some of the e ffects o f gamma irrad ia tion on its physical and b io log ica l ch aracteris tics . Note in F ig .5 that the two-pulsed sound is b lurred and distorted fo llow ing ir ra d ia ­tion with 10 kR. A lso , a ch a racteris tic component is delayed. Tab le III shows the responses o f norm al stock flie s and 'abnorm al' stock flie s (b e lieved exposed to ex cess ive tem perature in shipment) to combinations o f reproduced m ale ca llin g sound and extracts o f m ale pheromone (g rac iou s ly supplied by D r. J .L . Nation, U n ivers ity o f F lo r id a , Department of Entom ology and N em ato logy). In a ll com parisons, the communication

IAEA-PL-582/3 29

5<ш

FIG. 5. Sound frequency signatures o f male A . suspensa; a comparison o f laboratory stock flies irradiated with 10 kR2 days before adult eclosion and unirradiated stock Hies.

T A B L E III. RESPONSES OF Anastrepha suspensa TO S IG N ALLIN G SOUNDS, PHEROM ONE E X TR A C TS AND L IV E M ALES

Average No. o f flies responding

Normal Abnormal13

Male to male 14.4 6.7

Male to sound 13.9 4.3

Male to extract 13.0 7.1

Male to sound + extract 13.4 2.0

Female to male 19.1 11.3

Female to sound 12.9 6.0

Female to extract 18.9 11.3

Female to sound + extract 19.8 8.3

a Sixteen replications o f normal flies, three of abnormal flies, b Flies exposed to detrimental conditions during shipping

30 CHAMBERS

response of the abnorm al flie s was decreased . I repeat that these data are p re lim in a ry and inconclusive, but they indicate a line o f research we find m ost in teresting.

T estin g postm ating factors

In the in terest o f b rev ity I present here a partia l lis t o f re fe ren ces to studies o f the factors a ffecting postm ating success, with b r ie f descriptions o f the findings. The procedure w ill indicate some o f the ways postmating success can be m easured and w ill indicate the im portance such factors may have in ach ieving the ob jective of s te r ile re leases .

A . Anwar et al. (1971); h is to log ica l study showed that M editerranean fru it flie s irrad ia ted as adults contained m ore sperm than those irrad ia ted as pupae.

B. Barton Browne (1957); mated fem ale Dacus tryon i rep e l subsequent mating attempts by m ales.

C. Tzanakakis et al. (1968); a substance transm itted in the semen may inhibit subsequent fem a le mating in D. oleae.

D. Nakagawa et al. (1971); m ale M editerranean fru it flie s are po ly­gamous but fem ales rem ated less frequently , with recep tiv ity in verse ly co rre la ted with the amount of sperm rem ain ing in the sperm athecae.

E. Ohinata et al. (1971); m ale M editerranean fru it flie s irrad ia ted as'adults tran s ferred m ore sperm than those irrad ia ted as pupae.

F . K a tiya r and R am irez (1970); fem a le M editerranean fru it fl ie s mated sequentia lly with s te r iliz ed and fe r t i le m ales demonstrated that sperm m ixing occurs and that a fe r t i le mating a fter a s te r ile mating a ltered fem ale fe r t i l ity m ore than the re v e rs e sequence.

5. CONCLUSIONS

A. Quality is a value judgement, not a b io log ica l constant.

B. Function is the name o f the gam e, not productiveness and not naturalness.

C. 'Unnaturalness1 should be a warning signal, not a c r ite r ion for re jection .

D. The native ta rget insect is the best standard o f re fe ren ce , but an in ternal standard is acceptable if its lim itations are acknowledged.

E . P erfo rm an ce le v e ls are needed, but accord ing to behavioural tra its and function, they may acceptably be substandard, standard, or above standard.

IAEA -PL-582/3 31

F . Some behavioural tra its are obviously needed, but they may not be the best tra its to m easure and should never be the only tra its m easured.

G. Know your insect in the fie ld and labora tory , know your program m e function, know your p rogram m e lim ita tions, and g ive quality a proportionate p r io r ity .

H. T es t at least:a. Adaptedness — do you s t ill have an insect su ffic ien tly like the

ta rget insect to ach ieve its function?b. M otility — can and w ill your insect get to the ta rget?c. Reproductive success — can the flie s you produce suppress

native fly fe r t i l ity with acceptable e ffic ien cy?

R E F E R E N C E S

ANWAR, MAHMOOD, CHAMBERS, D .L ., OHINATA, K ., KOBAYASHI, R.M. (1971), Radiation sterilization o f the Mediterranean fruit fly (Diptera: Tephritidae): Comparison o f spermatogenesis in flies treated as pupae or adults, Ann. Entomol. Soc. Am. 64(3), p. 627.

BARTON BROWNE, L. (1957), An investigation of the low frequency of mating of the Queensland fruit fly Strumeta tryoni Frogg, Aust. J. Zool. 5, p .159.

BATEMAN, M .A . (1972), "The ecology o f fruit flies", Annual Review o f Entomology, V o l.17 (R.F. SMITH, MITTLER, T .R ., SMITH, C .N ., Eds), Annual Reviews, Inc., Palo Alto, p .493.

BOLLER, E. (1972), Behavioral aspects o f mass-rearing o f insects, Entomophaga 17(1), p .9.

FRIED, M. (1971), Determination o f sterile-insect competitiveness, J. Econ. Entomol. 64(4), p .869.

HANIOTAKIS, G.E. (1973), Sexual competitiveness o f metepa-sterilized males o f Dacus oleae. Environ. Entomol. 2(5), p .731.

HOLBROOK, F .R ., FUJIMOTO, M.S. (1970), Mating competitiveness o f unirradiated and irradiated Mediterranean fruit flies, J. Econ. Entomol. 63(4), p. 1175.

KATIYAR, K .P ., RAMIREZ, E. (1970), "Some effects o f gamma radiation on the sexual vigour of Ceratitis capitata (Wiedemann)", Sterile-male Technique for Control o f Fruit Flies (Proc. Panel Vienna, 1969), IAEA, Vienna, p .83.

KEISER, I . , KOBAYASHI, R .M ., CHAMBERS, D .L ., SCHNEIDER, E. (1973), Relation o f sexual dimorphism in the wings, potential stridulation, and illumination to mating o f oriental fruit flies, melon flies, and Mediterranean fruit flies in Hawaii, Ann. Entomol. Soc. Am. 66(5), p .937.

LANGLEY, P. A. (1970), "Physiology of the Mediterranean fruit fly in relation to the sterile-male technique” , Sterile-male Technique for Control of Fruit Flies (Proc. Panel Vienna, 1969), IAEA, Vienna, p .25.

LEPPLA, N .C ., SPANGLER, H.G. (1971), A flight-cage actograph for recording circadian periodicity of pink bollworm moths, Ann. Entomol. Soc. Am. 64(6), p .1431.

NAKAGAWA, S., FARIAS, G.J., SUDA, D ., CUNNINGHAM, R.T . CHAMBERS, D.L. (1971), Reproduction o f the Mediterranean fruit fly: frequency of mating in the laboratory, Ann. Entomol. Soc. Am. 64(4), p .949.

OHINATA, K ., CHAMBERS, D.L. , FUJIMOTO, М ., KASHIWAI, S., MIYABARA, R. (1971), Sterilization o f the Mediterranean fruit fly by irradiation: comparative mating effectiveness of treated pupae and adults,J. Econ. Entomol. 64(4), p .781.

PROKOPY, R.J. (1968), Visual responses o f apple maggot flies, Rhagoletis pomonella: orchard studies, Entomologia Exp. Appl. 11, p .403.

PROKOPY, R.J. (1975), these Proceedings.

3 2 CHAMBERS

SCHOENLEBER, L .G ., WHITE, L .D ., BUTT, B.A. (1970), Flight mill system for studying insect behaviour, USDA-ARS 42-164, 7 pp.

SCHROEDER, W .J.. CHAMBERS, D .L ., MIYABARA, R.Y. (1973a), Reproduction o f the melon fly: mating activity and mating compatibility o f flies treated to function in sterile-release programs, J. Econ. Entomol.66(3), p .661.

SCHROEDER, W. J., CHAMBERS, D .L., MIYABARA, R.Y. (1973b), Mediterranean fruit fly: propensity to flight o f sterilized flies, J. Econ. Entomol. 66(6), p .1261.

SHARP, J.L (1972), Effects o f increasing dosages of gamma irradiation on wingbeat frequencies of Dacus dorsalis Hendel males and females at different age levels, Proc. Hawaii Entomol. Soc. 21(2), p .257.

TURNER, W .K , CHARITY, L.F. (1971), Determining response o f insects to radiation by continuous monitoring o f their carbon dioxide output, Ann. Entomol. Soc. Am. 64(2), p .419.

TURNER, W .K ., CHARITY, L .F ., SODERHOLM, L.H. (1973), Use o f automation and computer analysis in a study o f insect response to radiation, Trans. Am. Soc. Agrie. Engineers 16(5), p .956.

TZANAKAKIS, M .E ., TSITSIPIS, J .A ., ECONOMOPOULOS, A.P. (1968), Frequency o f mating in females o f the olive fruit fly under laboratory conditions, J. Econ. Entomol. 61(5), p. 1309.

WEBB, J.C. (1973), Analysis and identification of specialized sounds possibly used by the Caribbean fruit fly Anastrepha suspensa (Loew) for communication purposes, Doctoral dissertation, University o f Tennessee, Knoxville (Univ. Microfilms, Inc., Ann Arbor, Mich.).

WEIDHAAS, D.E ., LABRECQUE, G .C ., LOFGREN, C .S ., SCHMIDT, C.H. (1972), Insect sterility in population dynamics research, Bull. World Health Organ. 47, p .309.

IAEA-PL-582/4

PROGRESS OF THE PILOT TEST AT LANAI AGAINST MEDITERRANEAN FRUIT FLIES AND MELON FLIES*

E.J. HARRIS, R.T. CUNNINGHAM,N. TAN AKA , K. OHINATA Hawaiian Fruit Flies Lab.,USDA, ARS,Honolulu, Hawaii,United States o f America

Abstract

PROGRESS OF THE PILOT TEST AT LANAI AGAINST MEDITERRANEAN FRUIT FLIES AND MELON FLIES.A pilot test programme is underway on Lanai, State of Hawaii. The objective is the suppression of the

Mediterranean fruit fly with sterile medfly releases and the melon fly with male annihilation treatments. Plans have been laid, and preliminary testing has begun to determine the most effective approaches.

INTRO D U CTIO N

The presence of insect pests such as the m elon fly , Dacus cucurbitae Coqu illett, the orien ta l fru it fly , D. dorsa lis Hendel, and the M editerranean fru it fly , C era titis capitata (W iedemann), in the State of Hawaii presents a serious obstacle to the development of d iv e rs ified agricu lture. Not only do these f l ie s cause d irect in jury to fru its and vegetab les; they also make it n ecessa ry fo r the state and fed e ra l governm ents to maintain a la rge quarantine program m e to m in im ize the r isk of acciden ta lly introducing the f l ie s into the mainland United States. Indeed, fru it f l ie s have been estim ated to cost Hawaii US $ 52 57 3 2001 per yea r by th e ir existence in the state. T h e re ­fo re , since state and fed e ra l o ffic ia ls would like to erad icate o r neutra lize the im pact of these f l ie s on the econom y of Hawaii, the Hawaiian F ru it F lie s Labora tory of A gricu ltu ra l R esearch S erv ice , US Department of A gricu ltu re, has re c e iv ed spec ia l funds to study methods fo r la rg e -a rea treatm ent and to determ ine the fea s ib ility of erad iacting fru it f l ie s from Hawaii.

LO C ATIO N OF TE ST AND OBJECTIVES

The 381-km2 island of Lanai (F ig . 1) was se lected fo r the p ilot test because its s ize and location, 119 km from Honolulu, are appropriate to the resou rces and equipment that are availab le to c a rry out the experim ent.

* Mention of a pesticide or a commercial product or company in this paper does not constitute a recommendation or an endorsement by the USDA.

1 An Appraisal of the Importance of Fruit Flies to Hawaii’s Economy,prepared by the staff of the Division of Plant Industry, State of Hawaii,Department of Agriculture Sept. 29, 1966.

33

34 HARRIS et al.

L- . I I

miles

FIG. 1. Map of Lanai showing the topographie features of the island and the distribution of Hawaiian tephritid fruit flies. Elevation in feet (ft -s- 3.28 = metres). Distance in miles (miles x 1.61 = kilometres). © = medfly; © = melon fly; 0 = oriental fruit fly.

In addition, the island has appreciable populations of a ll three species of flie s . Since the islands o f M olokai and Maui are located 1 3 - 1 6 km north and east northeast, resp ec tive ly , from Lanai, we do not expect com plete erad ication of the fru it f l ie s from Lanai. They w ill be able to m igrate on the trade winds from the neighbouring islands.

Lanai is usually a d ry island (about half re c e iv e s less than 51 cm of rain per y ea r ), and w ild host plants fo r Tephritidae are found fo r the most part in the 31-km2 area that has higher ra in fa ll, the cen tra l high peak (305 - 610-m elevation ). How ever, cultivated and w ild hosts a lso occur in the cen tra l v illa g e (1.29-km2 area, 2500 population) and in a few other sm all areas. The cu ltivated hosts are probably ch ie fly im portant in helping to c a rry the m ed fly over between guava seasons (though there is never a tim e without guava) and in provid ing adult food and shelter.

The program m e w ill consist of s ix essen tia lly separate operations: a fru it f ly survey; the developm ent of methods of treating la rge areas; two program m es, one invo lv ing the re lease of s te r ile M editerranean fru it f l ie s (m ed fly ) and one involving treatm ent of m elon f l ie s by m ale annihilation and by re lea ses of s te r ile m elon flie s ; studies of the environm ental im pact of the program m e; and the development of system s of evaluating the program m e.

IAEA-PL-582/4 3 5

The survey program m e is now in p rogress and w ill continue throughout the experim ent (it consists ch ie fly in m onitoring the catches in approxim ately 225 tr ip le ts of p lastic traps (675 tota l), one each fo r the m edfly, m elon fly , and orien ta l fru it fly , distributed throughout a ll the access ib le areas of the island) because trap catches are the ch ief too l in determ in ing the pattern of d istribution of both re leased and native flie s . F o r exam ple, recaptures of re leased dye-m arked m ed flies and melon fl ie s are used to delineate d ispersa l, su rviva l, and overflood ing patterns, which suggest m odifactions in treatm ent. A lso , the in form ation from the 67 5 traps is being supplemented by surveys fo r host b iom ass indices of fru it in festation and evaluation of the g ra v id ity and insem ination of fem a les captured in liqu id -bait traps. Thus, the su rvey and a lso the other operations support the e ffo r t to demon­strate suppression.

As the program m e indicates, we are giving top p r io r ity to the developm ent of the s te r ile - in sec t technique fo r control of the m edfly; next most im portant is the developm ent of the m ale-annih ilation technique and the re lea se of s te r ile f l ie s fo r control of the m elon fly. We have a lready developed the m ale-annih ilation technique fo r control of the orien ta l fru it f ly su ffic ien tly so that we are confident it w ill p er fo rm sa tis fa c to rily . N everth e less , i f the p ilot test p rog resses w e ll against the m edfly and the m elon f ly and resou rces perm it, we w ill en large the program m e to include fu rther developm ent of the m ale-annih ilation technique against the orien ta l fru it fly . In this event suppression of a ll th ree species of fru it f l ie s on Lanai would be achieved.

RELEASES OF S TE R ILE M ED ITE R R AN E AN F R U IT FL IE S

We began re lea ses of s te r ile m ed flies in M ay 197 3 at an average rate o f 1 - 10 m illion pupae per week. A t that tim e, the pupae w ere rea red in Honolulu (irrad ia ted with 10 krad 1 day be fo re adult ec los ion and dyed with Calco® Blue powder) and a irm a iled to Lanai in anaerobic poly bags (Tanaka et a l., 1972). Th is modest production has now been increased to 15 to 20 m illion pupae per week. We handle some 4 - 5 m illion of the fl ie s each week by bulk ch illing and holding at 3 - 5°C, irrad ia tin g (as adults at 10 krad) in lots of 500 - 7 00 thousand, and packaging in paper bags (25 000 per bag) m ixed with sphagnum m oss, a lfa lfa hay, o r oat straw (Schroeder et al. of this labora tory , unpublished data). The bagged f lie s are subsequently dropped on Lanai from a light airplane. A lso , about 1 m illion fl ie s are dropped as naked pupae o r adults from a re fr ig e ra ted dispensing machine supplied by the An im al and P lant Health Inspection Service (APH IS ). The rem ainder of the f lie s , 1 0 - 1 5 m illion , are irrad ia ted as pupae (in a n itrogen atm osphere) at 1 2 krad, shipped in poly bags, and re leased 2 - 4 tim es per week at ground sites from 1 .892-litre p lastic buckets that hold as many as 15 000 - 20 000 pupae per bucket. The 600 ground re lea se s ites are located throughout the 31-km 2 area of the island where breed ing hosts are found. Thus, the a er ia l re lea ses supplement the ground re leases .

The new methods of handling, irrad ia ting, and re leas in g the s te r ile m ed flies evo lved from a s e r ie s of p re lim in a ry tests made to com pare the su rv iva l of f l ie s re leased as fed adults with that of f l ie s allowed to em erge as pupae in the fie ld . The dyed irrad ia ted pupae w ere placed in 5.44-kg paper bags (N adel et al., 1967) at a rate of 1500 pupae per bag, and each bag was provided with a food and water source. Then the f l ie s w ere held in

36 HARRIS et al.

ambient tem peratu res until most of the adults em erged. A t this point, about 1 0 0 000 o f these f l ie s and 1 0 0 000 pupae (handled as described ) w ere placed at each o f 10 s ites on Lanai. The resu lting re c o v e ry from the adult re leases was about 2 tim es the re c o v e ry from the pupal re lea ses in the two tr ia ls . (H ow ever, because of lo g is tica l d ifficu lties , most f l ie s that we have re leased thus fa r have been irrad ia ted as pupae.) L ik ew ise , a e r ia l drops of r e f r ig ­erated adults o r undyed naked pupae w ere com pared with ground re leases of pupae. The ra tes o f r e c o v e ry of pupae w ere s im ila r; the ra tes fo r the re fr ig e ra ted adults w ere much higher. N everth e less , re c o v e r ie s from a ll re lea ses w ere low , and the methods need fu rther refinem ent.

In itia lly , the d ispersa l and su rv iva l of adults em erg ing from the re leased pupae w ere low because o f the atypical harsh, windy, and dry conditions of the island; how ever, su rv iva l im proved when ra in fa ll increased. A lso , pupae in po ly bags w ere in jured and few er adults em erged when tem ­peratures rose above 25°C; this in jury is reduced by placing ice blocks in the wood shavings placed around the pupae when they are sent by a irm a il from Honolulu to Lanai. N everth e less , the system of shipping the pupae by m a il s t ill is supplemented by a ir fre igh t shipment to m in im ize overheating.

We a lso investigated the use of a er ia l sprays of P IB -7 hydrolysed p rote in -techn ica l malathion (4:1 ra tio ) applied 4 tim es at a rate o f 215 g active malathion per hectare to prevent the seasonal August peak of native m ed flies (we a lso assessed the sprays as a potential spot treatm ent fo r control in the m ed fly -b reed ing area ). S terile m ed flies , native m ed flies , and orien ta l fru it f l ie s w ere a ll k illed by the treatm ents, and the seasonal m ed fly peak did not occur; in addition, populations o f orien ta l fru it f l ie s in the area w ere kept low. H ow ever, the sprays w ere only e ffe c tiv e fo r 2 weeks, and they have been discontinued.

W ith the re lea ses , we are cu rren tly achieving an overflood ing ra tio of 80:1 re leased to native m ales, and the overflood ing ra tio is increasing. H ow ever, a fter any one re lea se , a number of traps catch only undyed f lie s (som e are undoubtedly s te r ile f l ie s that have lost dye). We expect to im prove g rea tly on this ra tio as we increase production, re -a llo ca te re lea se s ites, and use the s te r ile m ed flies m ore judiciously.

R e leases of s te r ile m ed flies w ill be continued at least through N ovem ber 1974 so we can m easure the incidence of m ed fly la rvae in the peak-season guava crop.

M A L E -A N N IH IL A T IO N T R E A T M E N T OF M ELON FL IE S

On Lanai, the m elon f ly is distributed in c lu sters in close association with cu ltivated or w ild breed ing hosts. Thus, the f ly is found in sm all ga r dens in the 1.29-km2 v illa g e and in o lder pineapple fie ld s where M om ord ica charantia, the p rincipa l breed ing host, grow s as a weed. The m ale- annihilation treatm ents w ill th ere fo re be applied to areas that have M om or­dica. These areas w ere delineated in co -opera tive studies with the C itrus Insects Investigations Labora tory , W eslaco, Texas (H art et a l., 1971) in which in fra red a e r ia l colour photographs w ere made of 7290 hectares of pineapple fie ld s . Th is rem ote sensing technique, a prom ising su rvey too l that we hope to use again, a llow ed us to iden tify 364.5 hectares o f pineapple fie ld s containing va r io u s -s ize patches of M om ordica.

IAEA-PL-582/4 37

The tests of m ale annihilation against m elon f l ie s are at present planned to p roceed as fo llow s: In the f ir s t place, to attract m elon fl ie s out of the pineapple fie ld s , we w ill use light a irc ra ft to apply 4.47 kg per hectare of Th ixcin -th ickened sprays of cue-lu re (Ohinata et a l., 1971) (60% cue-lu re + 10% Th ixcin + 30% naled) to 72.5 km2 around the p er im eter of pineapple fie ld s . A lso , we w ill apply four swaths, 0.161 km apart, extending 1.61 km out from the border of the pineapple fie ld s toward the sea. In addition, in the Keamoku Beach area on the north side of Lanai, three swaths w ill be applied extending from the shoreline inland, and a e r ia l sprays of the form ulation w il l be applied over the rem ain ing inhospitable area of the island (ca. 207.2 km2) at the rate of 140 g of m ixture per km2 at 3-week in terva ls (to ensure adequate coverage of the portion of the island that probably harbours only transient f lie s ). F ina lly , in the inhabited areas, the v illa g es , we w ill apply the m ixtures to pow erline poles, trees , hedges, and fence posts by squirting it from o il cans at a rate of 0.2 g per squirt per 15.25 m (148 or 174 squirts per hectare).

In the second place, 15.24-cm p ieces of 24-ply string saturated with 70% cue-lu re + 30% naled (0.9 of m ixture per 15.24-cm string) w ill be applied to 608 hectares of post-harvest pineapple fie ld s at a rate of 40 strings per hectare (91.5 m apart). H ow ever, we have since found that c igarette f i l t e r tips can be substituted fo r the strings. A lso , we w ill trea t 1012.5 - 1215 hectares of post-harvest pineapple fie ld s by locating redwood stakes (1.27 cm X 91.44 cm ) saturated with 4 - 6 g of 7 0% cue-lu re + 30% naled around the p e r im e te r of the 45.8-m beds at the rate of 12 stakes per hectare. F resh stakes w ill be set out at 2 -month in terva ls .

The rationale fo r the sequence is that the ease of application and good coverage obtainable with the thickened sprays w ill produce a m ore drastic population reduction than the strings o r f i l t e r tips. Then once suppression is achieved, it can be maintained and enhanced by the lon ger-las tin g strings or f i l t e r tips that take about tw ice as long to apply.

A p re lim in a ry treatm ent, a single a e r ia l sp ray of cue-lu re + naled thickened with Th ixcin , was applied to a 30.49 km X 0.805 km border s trip around one o f the fie ld s of pineapple. Im m ed ia te ly a fter the application, traps adjacent to this sprayed area showed a reduction in catch of 98% com pared with the pretreatm ent le ve l; a fter 2 weeks, the reduction was 8 8%. The spray was th ere fo re judged su ffic ien tly e fficac ious to use in the m ale-annih ilation program m e, and treatm ent in terva ls w ere set at 2 - 3 weeks. In another p re lim in a ry test, a 243-hectare M om ord ica -in fested pineapple fie ld was trea ted by distributing redwood stakes soaked at the tip with 5 g of cue-lu re + naled at the ra te of 12 stakes-per hectare. No m ale m elon f l ie s w ere reco ve red from that fie ld during the f ir s t 8 weeks post-treatm ent.

We have a lso been testing the equipment that w ill be used. F o r exam ple, in co -opera tive studies, A gricu ltu ra l R esearch Serv ice engineers in Yakim a, Washington, have developed a string cutter, a so lid pa rtic le auger, and a v iscou s-lu re spray pump that w ill be used to apply treatm ents from a ircra ft. The strin g cutter and auger w ere used to distribute m ale-annih ilation tre a t­ments in 688.5 h ectares of post-harvest pineapple fie ld s that had M om ordica in festations; the spray pump was used to apply spray to the uninhabited portions o f the island that are not in pineapple. A lso , in O ctober 197 3, we made fu rther checks of equipment and methods. The liqu id -lu re dispenser malfunctioned and requ ired extensive m odification and redesign .

38 HARRIS et al.

The treatm ents with 2. 36-cm p ieces o f 24-p ly strin g w ere not as e ffec tive as expected. F ina lly , heavy ra in fa ll in D ecem ber and January reduced the e ffec tiven ess o f the treatm ents.

COM M ENTS

The procedural d ifficu lties with the treatm ents against the m elon f ly have led to the decision to hold the m ale-annih ilation program m e in abeyance until we fin ish the re lea se program m e against the m edfly. Liqu id m a le- annihilation treatm ents only m ay be made fo r com patib ility with the re lea ses of s te r ile melon f l ie s to mop-up w ild f l ie s m issed by the treatm ents.

Our genera l s tra tegy requ ires that we f ir s t test the methods of tre a t­ment to determ ine the ir e fficacy . We must a lso determ ine the best way to conduct the experim ent on Lanai before we com m it ou rse lves com pletely to any one approach. When the data are not conclusive, the approach we choose w ill be based on the sim plest, least expensive, o r m ost lo g ica l method. We w ill keep our options open until we are sure we are proceeding in the righ t d irection . We make changes in our methods as needed and have been able to e ffe c t savings in the cost of m ateria ls and applications at the sam e tim e that we have im proved our methods.

R E F E R E N C E S

HART.W.G., INGLE, S.J., DAVIS, M.R., MANGUM.C., HIGGINS, A., BOLING, J.C. (1911), Some uses of infrared aerial color photography in entomology, Proc. Third Biennial Workshop in Color Aerial Photography in the Plant 1971.

NADEL, D.J., MONRO, J., PELEG, B.A., FIGDOR, H.C.F. (1967), A method of releasing sterile Mediterranean fruit fly adults from aircraft, J. Econ. Entomol. 60, p. 889.

OHINAXA, K ., STEINER, L.F., CUNNINGHAM, R.T., Thixcin®E as an extender of poisoned male lures to control fruit flies in Hawaii, J. Econ. Entomol. 64, p. 1250.

TANAKA, N., OHINATA.K., CHAMBERS, D.L., OKAMOTO, R. (1972), Transporting pupae of the melon fly in polyethylene bags, J. Econ. Entomol. 65, p. 1727.

IAEA-PL-582/5

THE PROCIDA MEDFLY PILOT EXPERIMENT

Status of the medfly control after two years of sterile-insect releases*

u. CIRIO

Laboratorio Applicazioni in Agricoltura,Comitato Nazionale per l'Energia Nucleare,Rome, Italy

Abstract

THE PROCIDA MEDFLY PILOT EXPERIMENT: STATUS OF THE MEDFLY CONTROL AFTER TWO YEARS OF STERILE-INSECT RELEASES.

The CNEN initiated in 1971 a four-year pilot experiment o f medñy control by the sterile insect technique on the island o f Procida. The mass rearing and sterilization o f the medfly, the logistic techniques, the evaluation method and the control strategy used in 1973 are described. The medfly was effectively suppressed by releasing a limited number o f sterile flies and by other simple control methods.

IN TRO D U CTIO N

During the past twenty yea rs , in sp ite o f extensive use o f pestic ides, the losses and problem s to the Ita lian fru it industry due to C eratitis capitata (W iedemann) have increased . It was recen tly estim ated in Italy that the loss of incom e due to this species is about 45 m illion do lla rs a y ea r [ 1 ] . The urgent need fo r a lternative methods to control m edfly induced the Labora tory fo r Application o f N uclear Techniques to A gricu ltu re , CNEN, under the auspices o f the IA E A , to exp lore the poss ib ilities of using the s te r ile - in s e c t technique (S IT ) in the Parthenopean islands [2 , 3 ]. These fir s t tr ia ls , conducted in collaboration with the Italian M in istry o f A gricu ltu re and F o re s try (M A F ), E U R ATO M and IA E A , proved v e ry prom ising. The necess ity , how ever, to have d e fin it iv e , p ractica l and econom ic data on the application o f this technique convinced CNEN to begin, in 1971, a fou r-y ea r pilot experim ent ch aracterized by eco log ica l studies during and a fte r the two in itia l y ea rs o f s te r ile fly re lea ses . Th is experim ent, located again on the island o f P roc ida , is ca rr ied out in collaboration with M A F and E U R ATO M . The present paper describ es the control strategy follow ed in the 1973 re leases and d iscusses the resu lts obtained.

* Contribution 395 from the CNEN Agricultural Laboratory, Casaccia Nuclear Studies Centre, S. Maria di Galeria, Rome, Italy*

39

40 CIRIO

FIG. 1. Release cage used for sterile medfly adults on the island o f Procida,

M A TE R IA LS AND METHODS

1 . Mass rea r in g and irrad ia tion o f m edfly

IAEA-PL-582/5 41

The fl ie s w ere rea red at the Casaccia in secta ry using the technique reported by De Murtas and C ir io [4 ] . During the w inter a C era titis w ild population from P roc id a was colon ized in the insectary . A t ir re g u la r in terva ls during the y ea r , many fl ie s co llected from fru its a r t if ic ia lly in fested in -fie ld cages at the in sectary w ere introduced into the mass rea r in g . Studies on the m odification o f egg incubation, cheaper la rva l d iets , and m echanization o f rea r in g procedures w ere ca rr ied out o r a re s t ill in p rog ress . The length o f the pupal stage was regu lated by va ry in g the tem peratu re from 15 to 25°C to synchronize adult em ergence. A few days b e fo re the end o f the pupal period a ll insects w ere coloured with d ifferen t fluorescen t dyes accord ing to the re lea se a reas . The s te r iliza tion o f marked adult fl ie s was accom plished at the 60Co irrad ia tion plant o f the A gricu ltu re Application Labora to ry o f CNEN — Casaccia Center — with a dose o f 10 000 (±10% ) rad . A fte r irrad ia tion , the s te r ile insects w e re transported during the night by car to P roc id a . During the f ir s t month, adult s te r iliza tion was accom plished by using paper bags as described by C ir io and De Murtas [5 ] . H ow ever, from June to O ctober, fo llow ing successfu l p re lim in ary t r ia ls , the adult flie s w ere irrad ia ted in spec ia l 80 cm X 40 cm X 28 cm cloth cages, each containing about 1 0 0 000 insects that had been placed in the cages 3 days b e fo re th e ir em ergence ( F i g . l ) . The cages w ere kept in a ir - conditioned ce lls at 25°C until the tim e of irrad ia tion . The em erged adults

■were fed by wetting strip s o f paper tow ellin g with w ater. The strips w ere hung in the cloth cages to in crease the support surface fo r the flie s . In addition to these cages, 50 paper bags (each containing approxim ately 10 000 insects ) w ere sent to P roc id a . These extra f lie s w ere re leased in a reas not eas ily access ib le by car.

2. D istribution o f s te r ile flie s

The re lea se o f s te r ile adult flie s on P roc id a began on 4 May 1973, la te r than planned in the control stra tegy . During the f ir s t month the paper bags with s te r ile insects w ere hung and ripped open m ainly in the m ost favourable m ed fly o ver-w in ter in g areas; these genera lly correspond with citrus cultivation. F rom June onwards, re lea ses w ere ca rr ied out using sm all cars ca rry in g two s te r ile insect cloth cages set upright and opened on the top. The re leases w ere made on a w eekly schedule along a ll roads of P roc id a , which p ractica lly a re no m ore than 200 m from each other.S te r ile m arked insects w ere a lso re leased on Isch ia and Monte di P roc ida to obtain in form ation on C era titis m ovem ent. The numbers o f s te r ile flie s re leased a re g iven in Tab le I. A fte r each re lea se the number of weak flie s rem ain ing on the bottom o f the cages was estim ated to calcu late the rea l number o f com petitive insects re leased .

3. Evaluation o f e ffec tiven ess o f m edfly control

In 1973, the methods o f evaluating control e ffectiveness w ere s im p lified in o rd e r to reduce the fie ld work and w ere res tr ic ted to the examination of fru it in festation and to trapping. On P roc id a , an accurate inspection of

42 CIRIO

T A B L E I. D A T A ON RELEASE OF STE R ILE M E D F L Y IN THE E X P E R IM E N T A L AND C O N TR O L AREASa

MONTHLOCALITY

Procida M. di Procidab Ischia

May 13 408 000 0 0

June 8 510 000 0 0

July 3 217 000 4 101 000 130 000

August 1 722 000 5 495 000 65 000

September 5 947 000 0 0

October 8 092 000 0 0

November 0 0 0

TOTAL 40 896 000 9 596 000 195 000

a Data refer to sterile adults that left the cages.k Releases were made in collaboration with the Experimental Station o f Italian Ministry o f Agriculture &

Forestry, Entomological Section, Portici, Naples.

fru it se lected in the 1 2 system atic sam pling areas as w e ll as in the control areas was ca rr ied out e v e ry week accord ing to the techniques described by De M urtas et a l. [ 2] . A ttack was always indicated by the presence o f mature la rv a e in the fru it. On the island, fu rther controls w ere made on fru its im ported from the mainland. A l l host fru its found in the sto res and suspected o f being in fested w ere gathered and put in specia l boxes to co llect the pupae. Ind irect control o f the e ffectiveness o f the techniques was ca rried out by trapping the f l ie s in the T rim ed lu re bait traps always present on P ro c id a and in the control a reas . The number and colour o f the captured flie s w ere com pared with those o f adults caught in Capri, Isch ia and Monte di P roc ida .

4. M ed fly control strategy

In 1973, the procedure fo r con tro lling C era titis on P roc id a was changed accord ing to the fo llow in g considerations:

(a) The c le a r ly successfu l 1972 P roc id a experim ent [ 5 ] ;(b) The lack o f lon g -te rm eradication in the previous y e a r 's P roc id a

p rogram m e (desp ite the continuous re lea se of 85 m illion s te r ile adult insects from M arch to the end of O ctober) due to the im m igration o f g rav id fem a les from the nearby areas [ 5 ] ;

(c) The eco log ica l in form ation co llected on P roc id a and control areas since 1967 [5 -1 3 ];

(d) The attempt to ach ieve the sam e resu lts as in 1972 with a cheaper control program m e using sm a ller numbers of s te r ile insects and s im p lify in g the techniques [ 14] .

IAEA-PL-582/S 43

P L A N N IN G SEQUENCES

FIG. 2. Strategy o f medfly control suggested for 1973 experimental programme on the island o f Procida.

4 4 CIRIO

The 1973 control p rogram m e (see d iagram in F ig . 2) can be divided into asequence of fiv e periods.

I. The f ir s t period was devoted to reducing the over-w in ter in g population by destroying the sour oranges and by in tensive sticky trapping. Th is la tte r work began at the end o f 1972 in o rd er to elim inate the adult population and to avoid the problem o f applying in sectic id es on the island. H ow ever, to fo llow the developm ent o f the natural m edfly population, about 1 0 % o f the sour oranges w ere le ft on se lected trees .

II. The second period was devoted to rep ress in g the reproductive rate of em erged fl ie s by using m assive re leases o f s te r ile in sects. The tim ing o f the application o f the S IT was established by:

The em ergence o f the f ir s t f l ie s from pupae co llected regu larly during the w in ter and spring from in fested sour oranges (key host in P roc ida );The f ir s t flie s captured in the sticky traps which rem ained in the fie ld until the f ir s t newly em erged w ild flie s w ere captured;The weather conditions.

R e leases w ere continued 2 months a fter the last reco rd of fl ie s em erging from pupae co llected from sour oranges. During this tim e it was assumed that the flie s could have about two generations in the fie ld .Th ese re lea ses w ere ca rr ied out at the ra te o f about 10 000 s te r ile flie s p er week distributed f ir s t on the o ver-w in ter in g m edfly areas and a fterw ards on a ll P roc id a cultivated areas.

III. The th ird period was dedicated to checking the newly em erged adults which cam e from the in fested fru its im ported to the island and from the oviposition o f grav id fem ales which im m igra ted from the nearby areas. Th is was done to establish the beginning o f the second re lea se phase.It was accom plished by checking the flie s em erg ing from infested fru its both co llected in the fie ld and found in fru it m arkets. A lso , 300 sticky traps w ere placed in the fie ld 20 days a fter the la test re lea se of insects in o rd er to reduce the number o f im m igran t m a les . The 20-day period was chosen because o f the short l i fe o f s te r ile male f l ie s during the sum m er months. A ll traps w ere rem oved a few days b e fo re the beginning o f a new distribution o f s te r ile m ed flies .

IV . The fourth period was devoted to rep ress in g the reproductive rate o f the resu rg in g loca l m ed fly population by re leas in g s te r ile insects fo r about 2 months.

V. The fifth period w ill again be dedicated to reducing the over-w in terin g m ed fly population.

RESU LTS AND DISCUSSION

Sam pling o f the m ed fly population on P roc id a b e fo re applying the S IT revea led a 4.1% in festation in sour oranges and few w ild m ales in the sticky traps in M arch. H ow ever, adverse weather conditions in spring delayed the beginning o f the s te r ile adult re lea se until May 3rd, i . e . about 10 days a fte r the em ergence o f the f ir s t m edfly adults from sour oranges. During the second period o f the experim ent, the w ild population was com pletely erad icated on P roc id a , but since the end o f August, lik e in 1972, a v e ry low

IAEA-PL-582/5 4 5

T A B L E II. RESULTS OF F R U IT IN SPE C TIO N FO R M E D F L Y IN F E S T A T IO N IN THE RELEASE AND C O N TRO L AREAS

MONTH

HOST FRUITS EXAMINED

APRICOT PEACH PEAR FIG

A В A В A В A В

Island of Procida

June 7975 0.0 13803 0. 0 - - - -

July 4890 0.0 14761 0.0 8725 0.0 160 0.0

August 110 0.0 12413 0.4 13240 0.0 15894 0. 0

September - - 12478 8.0 3900 0.0 19580 0.0

Octob er - - 2958 23.6 550 0.0 5148 1.3

Monte di Procida3

June 681 0.0 146 0. 0 32 0. 0 - -

July 2589 6.0 362 0.8 573 0.7 / /

August 262 80.1 58 32.7 739 17.6 / /

September - - 25 64. 0 360 33. 0 / /

October - - - - 477 50.1 / /

Island of Ischia3

June 205 0.0 40 0. 0 - - - -

July 373 3.2 217 0.2 214 0.0 / /

August 72 22.2 195 22.6 203 2.0 / /

September - - 619 69.8 196 24.4 / /

October - - 280 82.8 - - / /

Island of Capri

June - - - - - - - -

July 385 1.0 1250 0. 0 650 0.0 - -

August - - 755 40. 0 930 0.0 230 0.0

September - - 175 86.8 - - 200 1.5

October - - 143 100. 0 - - 212 30.6

a Data from Dr. Fimiani, Istituto di Entomología Agraria, Portici, Naples. A = No. of fruits examined В = percentage of infested fruits / = unknown data.

46 CIRIO

15-

14-

10 -

9-

< 7-(j></)ш 6 - _ i<

o_J5 U-U.0cr 3 -ШCÛ1 2- z

1 -

0 -

♦----♦ PROCIDA• CAPRI

■— -■ ISCHIA* ♦.* MONTE DI PROCIDA*

15 30 JUL. 15 30 AUG. 15 30 SEP 15

T I ME

30 OCT.

FIG.3. Number o f captured wild males on Procida and in control areas in 1973. (Data taken from Dr. Fimiani, Istituto di Entomología Agraria, Portici, Naples.)

in festation was found on the island due to im m igration of adults from Monte di P roc id a and Isch ia . In fact, the recaptu re o f m arked adults re leased in the most im portant in fested area of Monte di P roc id a and along the west coast o f Ischia con firm ed the thesis of a continuous im m igration o f m edfly from these areas to P roc id a since August. Th is in festation , which was a lm ost exc lu s ive ly lim ited to w ild peaches, was not stopped by the second r e lea se o f s te r ile adults at the end o f August.

H ow ever, p eriod ic examination o f host fru its in. the control a reas, where m ed fly is con tro lled by insectic id es , indicated that the attack on P roc ida was v e ry low (Tab le I I ) . Trapping of w ild adults in experim ental and control areas (F ig .3 ) a lso showed a good resu lt fo r the 1973 tr ia l p rogram m e, although a genera l delay was observed in the natural population in crease which did not reach the le v e l o f preced ing y ea rs . The d eg ree o f fru it in festation , how ever, con firm s the great ab ility of this species to in fest its host even at a low population density [ 8 ]. Th is behaviour o f the f l ie s must be ca re fu lly considered in planning the quantity of s te r ile insects to re lease . Th is quantity should m ainly assure a high probability of matings between s te r ile and w ild insects fo llow ing good d isp ersa l o f a su fficient number of s te r ile flie s in the selected experim ental area. In the P roc id a environment this number was established to be about 10 000 adults per ha. The resu lts

IAEA-PL-582/5 47

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48 CIRIO

T A B L E III. D A TA O F M E D F L Y W ILD M ALES C APTU R E D IN PRO CID A ISLAN D USING P L A S T IC TR A PS

CAUGHT WITH TRAP/DAYYEAR

JUN. JUL. AUG. SEP. OCT. NOV. DEC.

1968 0.25 6.23 26.66 48.63 14.59 1.56 0.21

1969a 0.75 1.84 2.83 51. 00 25.22 1.44 0.02

1970 0.38 - 22.17 - 19.72 - -

1971b - 19. 23° - 68.76° 55.18c 8.64° 2. 08c

1972a 0.00 0.00 0.01 0.07 0.17 1. 87 c о CO о

1973a 0.00 0. 00 0.01 0.15 0.33

a Years o f SIT application k Data from Dr. de Murtas (CNEN) c Capture with sticky traps.

T A B L E IV., INCIDENCE OF M E D F L Y LA R V A E IN PRO C ID A ISLAND

YEAR JUN. JUL. AUG. SEP. OCT. NOV.b DEC.b

1967 с С c X X X X X X X X xxxx X X X X

1968 X X X X X X X X X X X X X X X X xxxx X X X X

1969a x X X X X X X X X X xxxx X X X X

1970 x X X X X X X X X X X X X X X X xxxx xxxx

1971 X X X X X X X X xxxx X X X X xxxx xxxx

1972a 0 0 X X X X X

1973a 0 0 X X X X с

a = year o f SIT application; b = attack related to the orange fertile stings; с = fruits not inspected.

Fruits examined: June and July — apricots and peaches; August — peaches, pears and figs; September and October — figs and peaches; November and December — oranges and tangerines. Level o f infestation: 0 = zero; x = slight (< 10%); xx = moderate (10 - 30%); xxx = strong (30 - 60%); xxxx = very strong (> 60%).

obtained in 1973 on P ro c id a showed that by using a strategy of re leas in g considerab ly few e r s te r ile insects than in 1972, m edfly con tro l was s till v e ry e ffe c t iv e (F ig .4 ). Th is was possib le only because o f good integration o f other con tro l techniques and v e ry accurate sam pling o f the m edfly population. The m ost im portant advantages o f this new m edfly control s tra tegy w ere the reduction of.the cost of the experim ent and b e tte r c o lla ­boration with the fa rm ers in trapping and sour orange destruction. H ow ever,

IAEA-PL-582/5 49

som e problem s did a r is e during the 1973 application o f the S IT. F irs t , the new re lea se procedure took m ore tim e than when the paper bags w ere used because few fl ie s le ft the cloth cages when the ca r was m oving. Second, it was observed that about 35% o f the s te r ile m ed flies w ere weak and unable to fly from the cages. Th is c lea r ly indicated the n ecessity to m odify the procedure o f handling the fl ie s in the cloth cages which, in contrast, w ere v e ry p ractica l fo r the s te r iliza tion o f la rg e numbers o f adults in a short t im e. Ways of im proving the techniques used can be eas ily foreseen .

At the end of the s te r ile m edfly re lea se experim ents on the island o f P ro c id a there w e re no doubts about the e ffectiveness o f the SIT to control this spec ies , as is shown in Tab les III and IV . H ow ever, research on P ro c id a w ill continue fo r som e yea rs to estim ate the changes induced in this environm ent a fter a lengthy and strong reduction o f the m edfly population. E ffo r ts w ill be made to have a final analysis o f a ll resu lts and to estim ate the cost o f m edfly control. Th is in form ation should prove v e ry important when im plem enting the la rg e new SIT p rogram m es which CNEN recen tly prom oted in Sardinia and Latium .

R E F E R E N C E S

[1 ] PICECE, P ., Report on problems dealing with the presence o f Ceratitis capitata Wied. in Italy, JointEPPO/OILB Conference on Ceratitis capitata, Madrid, 19-21 May 1970.

[2 ] De MURTAS, I.D . , CIRIO, U. , GUERRIERI, G ., ENKERLIN-S, D. , ”An experiment to control the Mediterranean fruit fly on the island o f Procida by sterile-insect technique", Sterile-Male Technique for Control o f Fruit Flies (Proc. Panel Vienna, 1969), IAEA, Vienna (1970) 59.

[3 ] NADEL, D. J. , GUERRIERI, G ., "Experiments on Mediterranean fruit fly control with the sterile-maletechnique", Sterile-Male Technique for Eradication or Control o f Harmful Insects (Proc. Panel Vienna, 1968), IAEA, Vienna (1969) 97.

[4 ] De MURTAS, I . , CIRIO, U ., L'allevamento massivo della mosca della frutta (Ceratitis capitata Wied. ) nell'insettario della Casaccia ed aspetti economici di lotta autocida, IX Congresso Italiano di Entorno logia, Siena, giugno 1972 (in press).

[5 ] CIRIO, U. , De MURTAS, I . , "Status o f Mediterranean fruit fly control by the sterile-male technique on the island o f Procida", The Sterile-Insect Technique and its Field Applications (Proc. Panel Vienna, 1972), IAEA, Vienna (1974) 5,

[6 ] CIRIO, U. , Influence de l'alimentation larvaire sur la longévité et la fécondité de Ceratitis capitata W ied., Joint EPPO/OILB Conference on Ceratitis capitata, Madrid, 19-21 May 1970.

[7 ] CIRIO, U. , De MURTAS, I . , Distribuzione e ricattura di adulti radiosterilizzati di Ceratitis capitata W ied ., IX Congresso Italiano diEntom., Siena, giugno 1972 (in press).

[8 ] CIRIO, U. , De MURTAS, I. , GOZZO, S. , ENKERLIN-S, D. , Preliminary ecological observation o f Ceratitis capitata Wied. on Procida island with a view to an attempt to control by the sterile-male technique, Boll. Lab. Entom. Agr. "Filippo Silvestri" (in press).

[9 ] De MURTAS, I . , CIRIO, U . , ENKERLIN-S, D ., Dispersion de Ceratitis capitata Wied. dans l ’î le de Procida (Italy), OEPP Publication, Bull. No. 6 (1972) 69.

[10 ] De MURTAS, I. , CIRIO, U . , ENKERLIN-S, D. , Distribution o f sterilized Mediterranean fruit fly on Procida and its relation to doses and feeding, OEPP Publication, Bull. No. 6 (1972).

[11 ] FIMIANI, P . , Osservazioni bioecologiche sulla mosca della frutta (Ceratitis capitata Wied. ) effettuate te nella zona di Monte di Procida (Napoli) negli anni 1968-1969, Boll. Lab. Entom. Agr. "Filippo Silvestri", Portici, Vol. XXX (1972) 71.

[12 ] FIMIANI, P. , TRAFAGLIA, A. , Influenza delle condizioni climatiche sull'attività moltiplicativa della Ceratitis capitata W ied., Ann, Fac. Sci. Agr. Portici (1972).

[13 ] FIMIANI, P . , PANDOLFO, F. , Fluttuazioni delle popolazioni di adulti di mosca della frutta nel litorale flegreo, Inf. tore Fitopat. (5 (1973) 13.

[14 ] CIRIO, U. , Basi ecologiche per un programma di lotta contro la Ceratitis capitata Wied. nell'isola di Procida (in press).

lAEA-PL-582/20

GENETIC CONTROL OF Ceratitis capitata

Practical application of the sterile-insect technique*

L. MELLADO, P. ROS, M. ARROYO, E. CASTILLO

Instituto Nacional de Investigaciones Agronómicas,

Madrid, Spain

Abstraer

GENETIC CONTROL OF Ceratitis capitata: PRACTICAL APPLICATION OF THE STERILE-INSECT TECHNIQUE.Since 1965 the INI A has been carrying out a programme of biological control of Ceratitis capitata

(Wiedemann) by means of the sterile-insect technique (SIT). Preliminary field experiments in 1969 in the province of Murcia, Spain, showed the method to be effective when applied in small isolated areas. New field experiments in 1972 in the province of Granada showed that it was possible to protect a semi-isolated area of 100 ha by creating peripheral ’’barriers" of sterile insects. No "sterile punctures" were observed in the fruit o f the release area. In 1973, mass-rearing techniques were improved and methods for shipment o f refrigerated adults instead o f pupae were developed. Results of these experiments confirm (a) that the SIT is fully effective in the control of C_. capitata, (b) that shipment of insects in the adult stage is more effective than in the pupal stage, and (c) that improvement in the rearing system can reduce the cost of production of irradiated insects by 607?.

INTRO D U CTIO N

1. Background

In 1965 the National Institute fo r A gricu ltu ra l R esearch (IN IA ) started a program m e o f b io lo g ica l con tro l o f C era titis capitata (W iedemann) by the s te r ile - in sec t technique (S IT ). Its ultim ate aim was to develop a technique which could be used in suitable combination with conventional system s to erad icate o r con tro l the pest, avoiding at the sam e tim e a s e r ie s o f undesira­b le e ffec ts (environm ental pollution and disturbance o f the b io log ica l equ ilibrium ) resu lting from the exclu sive use o f chem ica l p estic id es .

Between 1966 and 1969 a s e r ie s o f basic investigations was c a rr ied out in o rd er to im prove the methods o f la rg e -s c a le rea rin g and s te r iliza tion [3 , 5, 7, 9 ]. A t the same tim e, sm a ll-sca le fie ld applications w ere p e r ­form ed in o rd e r to study the methods o f re lea se o f insects and the e ffic ien cy o f the system [1 , 4, 6 , 7, 9 ]. In 1969, in the p rovince o f M urcia , an e x p e r i­ment was conducted fo r the f ir s t tim e in Spain aimed at con tro lling the pest in a sm all regu la r plantation o f c itrus and stone-fru it trees by the SIT exc lu s ive ly . The resu lts w ere fu lly sa tis fac tory and showed that the method was fu lly e ffe c tiv e when applied in sm all iso lated areas [ 8 , 9, 12] . During 1970, 1971 and 1972, labora tory investigations [11, 12] and sm a ll-s ca le fie ld experim ents [ 2 , 1 2 ] w ere continued, during which a study was made o f some prob lem s which needed to be solved so that the method could be

* This work was supported by the International Atomic Energy Agency (Research Contract No. 848/R3/RB).

51

5 2 MELLADO et al.

applied econom ica lly on a la rge sca le, nam ely irrad ia tion o f adults, su rv iva l and d ispers ion o f s te r ile insects in the fie ld , methods o f re lea se , occurrence o f s te r ile punctures in stone-fru it trees , and eco log ica l aspects.

In 1972 a new fie ld experim ent was ca rr ied out in the province o f Granada over an area o f som e 1 0 0 ha, where the pest was con tro lled en tire ly e ffe c t iv e ly by creating p eriph era l 'b a r r ie r s ' o f s te r ile insects [ 13]. The prob lem o f 's te r ile punctures' in the fru it o f the re lea se area was elim inated fu lly by this procedure.

2. P resen t status

The p resen t status, as resu lting from the ac tiv ities described , can be sum m arized as fo llow s:

(a) The 1969 experim ents dem onstrated that in su ffic ien tly iso lated areas the application o f the SIT is by its e lf fu lly e ffe c t iv e fo r the con tro l o f C . capitata, even when the native population is la rg e .The 1972 [13 ] and 1'973 fie ld experim ents, described in the present paper, have con firm ed the e ffic ien cy o f the technique;

(b) A prob lem encountered during the 1969 experim ent was the appearance o f s te r ile punctures in stone-fru its produced by irrad ia ted fem a les . These punctures do not a ffect the quality o r health o f the fru it but can, to a certa in extent, im pa ir its appearance. The experim ents ca rr ied out in 1970, 1971 and 1972 showed that, except in some va r ie t ie s o f peach, the s te r ile punctures w ere not v is ib le upon norm al inspection and did not th ere fo re constitute a serious prob lem as had seem ed to be the case at the beginning [ 1 0 ] ;

(c) The exc lu s ive application o f this technique as the sole method o f con tro l is, at present, excess ive ly costly . Im provem ent o f techniques and m echanization o f operations fo r a la rg e -s ca le p rogram m e would o f course lead to a substantial reduction in costs. The use o f the technique as part o f a p rogram m e o f in tegrated control, in which it would act on low -density populations, m ay a lready be econom ic under present circum stances.

1973 PRO G RAM M E

1. O b jectives

(a) To dem onstrate once m ore the e ffic ien cy o f the S IT fo r the control o f C_. capitata in the area treated in 1972, w ith the use o f im proved techniques;

(b) To continue the study o f the tim e-tab le o f the appearance o f С . capitata adults in an extensive area (som e 2 00 0 00 ha) and com pare it with that o f the previous yea rs fo r the purpose o f extending the experim enta l a rea in the future;

(c) T o re lea se s te r ile insects at the over-w in ter in g cen tres o f C_. capitata, esp ec ia lly on the coast;

IAE A-PL -582/2 О 53

( MED ITERR A N EA N SEA )

FIG. 1. General map of the area o f operation and location of the experimental area. The dates indicate the first appearance o f C. capitata adults in each of the localities in 1972 and 1973.

54 MELLADO et al.

IAEA-PL-582/20 5 5

(d) To try methods o f shipment and re lea se o f r e fr ig e ra ted m ales, com paring the e ffic ien cy with that o f shipment o f pupae;

(e) To p e r fo rm p re lim in a ry experim ents on a e r ia l re lea se techniques; ( f ) T o im prove the methods o f rea r in g and handling o f insects with

a v iew to reducing costs.

2. D escrip tion o f the experim enta l area

A l l fie ld experim ents w ere ca rr ied out in the sam e experim ental area as in 1972 (F ig . 1), described in deta il in an e a r l ie r publication [ 13 ].

In the coasta l areas o f the p rovince o f Granada, C_. capitata is an endem ic pest, and under the c lim atic conditions p reva ilin g there, the insect ex ists in the adult fo rm throughout the y ea r.

In the in te r io r o f the p rovince, the host plants a re essen tia lly stone- fru it trees in regu la r plantations. The ea r ly -r ip en in g fru its usually escape in festation by C_. capitata, which occurs as the season advances, presum ably as a resu lt o f the m igra tion o f insects from the w arm er coasta l areas [ 13].

The experim en ta l area fo r the application o f the S IT is situated at P in os Puente in the v a lle y o f Granada (850 m above sea le v e l). It co vers some 100 ha, including a regu la r 25 ha peach plantation with some 10 000 tre e s in a ll (F ig . 2). Th is a rea had a lready been used fo r experim ents in p revious y ea rs . In 1971, a study was made o f the cu ltivation and plant health p rac tices and data w ere obtained on the y ie ld and usual losses due to the pest. The d ispersion and longev ity o f s te r ile insects w ere also determ ined by experim enta l re lea ses [ 12 ]. In 1972, this area could be protected fu lly by the exc lu s ive use o f s te r ile insects [ 13].

The regu la r peach plantation includes the va r ie t ie s Jeronim o, Calabacero and C am pie l. Cam piel (600 tre e s ) is a v e r y la te -r ip en in g v a r ie ty and is m ore vu lnerab le to in festation by C_. cap itata .

The average total harvest o f the above-m entioned v a r ie t ie s is 220 000 kg, o f which 25 000 kg is accounted fo r by C am piel. In 1973, owing to c lim atic fa c to rs (fro s t), the harvest was v e ry low — 31 000 kg, including 5500 kg o f Cam piel.

The plantation is v e r y favourab ly situated fo r experim ents on b io log ica l con tro l by the S IT . Though lacking in topographic iso lation , it is surrounded by herbaceous crops; there are no known hosts within a radius o f about 5 km, except a few sm a ll iso la ted population fo c i.

The areas se lected as con tro l w ere three plantations at A rm illa ,Santa F e and Pu rch il. T h e ir altitudes and c lim atic , topographic and eco log ica l conditions are en tire ly s im ila r to those o f the experim en ta l area.

In a norm al y ea r , in spite o f chem ica l treatm ent, C_. capitata in festation a ffects at lea s t 5% o f the to ta l ea r ly output, reaching as much as 17% in the case o f the C am piel va r ie ty .

The main ch a ra c te r is tics and treatm ents p erfo rm ed in 1973 o f the experim en ta l and con tro l areas a re as fo llow s:

(1) P inos Puente (experim en ta l a rea )

A re a o f the peach plantation: 25 haA ge o f trees : 6 and 9 yearsV a r ie t ie s : Jeronim o, C alabacero and C am piel.

5 6 MELLADO et al.

1 0 ha6 yearsJerónim o and Calabacero Tw o treatm ents with 0.2% Lebaycid by fu ll spraying on 26 July and 10 August.

( 2 ) A r m i l l a ( c o n t r o l a r e a )

8 ha7 yea rsJerónim o and Calabacero Tw o treatm ents, one on 1 August with 0.2% Lebaycid by fu ll spraying and the other on 11 August with Lebaycid + 0.5% buminal in strips .

9 ha6 yearsJerónim o, Calabacero and Cam piel Tw o treatm ents with 0.2% Lebaycid by fu ll spraying on 26 July and on10 August fo r ea rly -r ip en in g va r ie t ie s .Tw o treatm ents with 0.2% Lebaycid by fu ll spraying on 29 August and 13 Septem ber fo r the late Cam piel va r ie ty .

3. M a ter ia l and methods

3.1. Capture o f native insects

P la s t ic fly - tra p s containing an attractant (T r im ed lu re ) and an insectic ide (D D VP) w ere set up at the lo ca lit ie s Jete, M o tr il, A lm uñecar, V e le z de Benaudalla, B eznar, Durcal, Santa F e and Guadix ( F i g . l ) .

Four traps w ere set up at each o f the above lo ca lit ie s in regu la r peach plantations. (In som e o f them other fru it tre e s a re also presen t, nam ely orange, sapod illa and aprico t. ) A l l traps w ere inspected tw ice a week and the inspection was continued until the presence o f the insect was con firm ed.

3.2. R e lease o f s te r ile insects

The re lea se o f s te r ile insects began towards the end o f M arch at A lm uñecar, Jete, M o tr il and V e le z , since (in accordance w ith the t im e ­table o f appearance o f C e ra tit is established in 1972 [ 13] ) these p laces w ere regarded as over-w in ter in g cen tres o f the f ly . F rom 11 July onwards a ll r e lea ses w ere ca rr ied out in the experim enta l area o f P inos Puente.

A rea o f the peach plantation: A ge o f trees :V a r ie tie s :Treatm ents:

(3) Santa F e (con tro l area)

A rea o f the peach plantation: , A ge o f trees :

V a r ie tie s :Treatm ents:

(4) Pu rch il (con tro l area )

A rea o f the peach plantation: A ge o f trees :V a rie tie s :Treatm ents:

lAEA-PL-582/20 5 7

A l l the insects cam e from the m ass a r t if ic ia l rea rin g labora tory in M adrid (E l Encin) and w ere supplied in the pupal o r in the adult stage. R e lea ses in the pupal fo rm w ere c a rr ied out by the method used in 1972 [ 13]. The adults w ere re leased at suitable p laces in the fie ld where the sun could rap id ly re v iv e them a fte r they had been kept at a low tem perature fo r seve ra l hours.

A l l re lea ses in the experim enta l area w ere ca rr ied out at points 1 to 7 (F ig . 2), except in the case o f the la te-rip en in g va r ie ty Cam piel, fo r which the insects w ere re leased in the in te r io r o f the p lot. The tim e-tab le o f r e lea ses and the number o f insects re leased a re g iven in Tab le I.

3.3. New method o f shipment o f pupae

C. capitata pupae w ere sent from the m ass -rea r in g cen tre to the experim enta l area in cages made o f a para lle lep iped wooden fram e with v e r y fine w ire netting on a ll sides.

Boxes w ith pupae (100 000) are stacked in these containers. The top o f the boxes consists o f p lastic netting through which adults em erg ing during the journey can leave the boxes and d isperse through the whole volum e o f the container. In this manner, when the shipment a rr iv e s in the fie ld , about 45% o f the insects are in the adult stage and in fu ll activ ity .

3.4. L abora to ry techniques fo r obtaining irrad ia ted adults

In o rd e r to s to re the la rg es t number o f irrad ia ted adults in the sm allest poss ib le space, we made som e cylinders o f cloth netting, 2150 m in height and 45 cm in d iam eter. The low er part contains a number o f c ircu la r p lastic trays and the upper part a funnel, the m a jor d iam eter o f which is equal to that o f the low er tray .

The bottom o f the tray contains a la y e r o f sawdust and above that a la y e r o f pupae (50 000). The whole tray is covered w ith a c ircu la r lid o f w ire netting, the openings in which a llow the n ew ly-em erged adults to pass but hold back the pupae.

These cy linders a re suspended from the roo f. As adults em erge from pupae, they pass through the netting, f ly upwards and scatter o ve r the whole surface o f the cy linder.

When there is a su ffic ien t quantity o f adults, the cages a re folded up, p laced in a re fr ig e ra ted cham ber and kept there fo r some tim e until the adults lo se activ ity . Then the cages are again suspended from the roo f, but now in the inverted position . The adults slip down along the fab ric and fa ll into the funnel, which d irec ts them into appropriate conta iners. The pupae cannot fa ll since they are retained by the w ire netting coverin g the tray.

The system described is s im ple, inexpensive and easy to operate.One can use e ither p rev iou s ly irrad ia ted pupae or n on -s terile pupae i f it is d es ired to irrad ia te them in the adult stage.

In the fo rm er case (method used fo r re lea ses in 1973), the adults w ere co llec ted in cy lin d rica l containers with v e ry fine m eta l gauze bases having a capacity o f 30 000 insects.

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IAEA-PL-582/20 61

3.5. Techniques o f shipment o f re fr ig e ra ted adults

A fte r the containers have been filled w ith adults, they are p laced in portab le ice -b oxes w ith s e ve ra l bags o f ic e . Thus packed they a re sent by night tra in to the experim enta l area. On a rr iva l, the adults are re leased at suitable points in the sun so that they rap id ly rega in the ir body tem pera ­ture and can resum e their norm al activ ity in the shortest possib le tim e.

In p ractice , this system o f shipment has been found to be v e r y e ffic ien t and, save fo r a few accidents (bursting o f ice bags), the percen tage o f m orta lity has always rem ained within v e ry low lim its (see Tab le I).

Depending on the ambient tem perature during the journey to the e x p e r i­m ental area, a g rea te r o r sm a lle r number o f ice bags are used so that the tem peratu re inside the box rem ains between 5 and 8 °C.

3.6. P re lim in a ry experim ents on a er ia l re leases

In the p resen t experim ent we ca rr ied out se ve ra l tr ia ls o f a e r ia l re lea se from P ip e r a irc ra ft . The p r im ary aim is to find a s im ple, econom ical method which could be applied on a la rge sca le by non -spec ia lized personnel.

During these tr ia ls the support m a ter ia l fo r C era titis adults was cork shavings and sm all po lystyrene ba lls . The la tte r m a ter ia l was found to behave b etter. A ltogeth er 2 500 000 adults w ere used in these experim ents.

The resu lts are prom ising but the system requ ires im provem ent, since v e ry high m orta lity was observed .

3.7. Inspection o f fru its

In the experim enta l and con tro l areas, sam ples o f fru its w ere taken in the p rocess o f harvesting (including fru its which had fa llen to the ground). Sam ples w ere co llec ted from cra tes at random on d iffe ren t days o f harvesting. The deta ils o f the number o f fru its inspected in each sam pling operation and o f the total harvest in each case a re g iven in Tab les II and III.

In the case o f the la te -r ip en in g va r ie ty Cam piel, sam ples w ere taken from the fru it-re c e iv in g bench and as the fru its w ere being packed in cra tes (Tab le IV ).

4. Results

F igu re 1 shows the dates o f appearance o f C_. capitata adults in each o f the lo ca lit ie s mentioned.

Tab les II and III g iv e data on C_. capitata in festation o f e a r lie r ripening peaches in the con tro l (A rm illa , Santa F e and Pu rch il) and in the experim enta l (P inos Puente) a reas.

Tab le IV presen ts data on C_. capitata in festation o f the la te-rip en in g peach va r ie ty C am piel in the con tro l (Pu rch il) and in the experim enta l (P inos Puente) a reas.

These tab les show that:

1. In a ll sam ples, in festation by C_. capitata o f the e a r lie r v a r ie t ie s o fpeach (Jeronim o and Ca labacero ) was le s s than 1.3% in the experim ental area, which was protected exc lu s ive ly by means o f s te r ile -in sec t re lea se .

62 MELLADO et al.

In sam ples taken from the con tro l areas (treated chem ica lly ) infestation va r ied between 1.2% and 17%. In non-treated areas, it lay between 92% and 100%.

2. The fo llow ing averages w ere obtained fo r infestation:E arly -r ip en in g va r ie tie s

E xperim en ta l a rea 0.12%

Contro l areas:

Santa Fe 2.20%Pu rch il 8.30%A rm illa 6.70%

Late-r ip en in g va r ie t ie s

E xperim en ta l area 0.30%C ontro l a rea (Pu rch il) 2.10%

3. It can be concluded from Tab le II that shipment o f insects in the adultstage (re fr ig e ra ted ) is m ore e ffe c tiv e than in the pupal stage. These resu lts can be sum m arized in the fo llow ing figu res (the 1972 data are cited fo r com parison):

1972 1973

T o ta l shipment o f pupae (m illions) 40.7 54.1T o ta l useful insects (m illions ) 25.0 32.4E ffic ien cy o f the method (%) 61.3 60.0To ta l shipment o f adults (m illions ) 23.0To ta l useful insects (m illions ) 18.1E ffic ien cy o f the method (%) 79.0

The above data indicate that shipments o f pupae g ive about 60% useful insects, as com pared w ith 79% in the case o f shipments o f adults.

T A B L E II. PE R C E N TA G E S O F C era tit is capitata IN F E S TA T IO N IN THEE X P E R IM E N T A L A R E A(Jerónim o and C alabacero va r ie t ie s )

Place DateFruit

harvested(kg)

Fruitinfested

(kg)°¡o

Pinos Puente 4, 5, 6/8 5 000 0.5 0.01

7/8 1 500 20 1.30

8/8 5 000 0.5 1.01

14/8 4 000 1 0.02

15/8 3 500 1.5 0.04

16/8 2 000 1 0.05

17/8 2 000 2 0.10

21/8 1 000 - 0.00

29/8 1 500 5 0.30

IAEA-PL-582/20 63

T A B L E III. PE R C E N TA G E OF. C era titis capitata IN F E S TA T IO N INC O N TR O L P LO TS(Jeronim o and Calabacero va r ie t ie s )

Place DateFruit

harvested

(kg)

Fruitinfested

( kg)

°Io Remarks

Santa Fe 30/7 1 100 28 2.50 2 treatments31/7 360 6 1.70 (Lebaycid) on7/8 3 000 49 1. 60 1 Aug. and 11 Aug.8/8 1 500 18 1.209/8 500 30 6.00

10/8 1 700 46 2.7011/8 2 000 39 1.8513/8 1 700 41 2.4015/8 500 20 4.00

Purchil 3/8 1 250 44 3.50 2 treatments4/8 2 480 97 3.90 (Lebaycid) on5/8 2 230 101 4.50 26 Jul. and 10 Aug.6/8 3 450 210 6.107/8 1 860 54 2.908/8 2 660 98 3.70

15/8 3 846 357 9.3016/8 2 300 200 8.7017/8 3 640 375 10.3020/8 5 435 717 13.2024/8 1 824 312 17.10

Armilla 31/7 - 5/8 12 600 542 4.30 2 treatments7/8 - 10/8 6 348 387 6.10 (Lebaycid) on

11/8-17/8 8 300 482 5.80 26 Jul. and 10 Aug.17/8-24/8 6 840 875 12. 80

Purchil 10/8 3 224 2 960 92.00 No chemicaltreatment

Armilla 6/8 2 840 2 840 100,00 No chemicaltreatment

4. Im provem ent in the rea r in g system s has reduced the cost o f production o f irrad ia ted insects in 1973 (in com parison with that in 1972) by approxim ately 60%.

5. It has not yet been possib le to develop a sa tis fac tory method o f s e r ia l re lea se .

64 MELLADO et al.

T A B L E IV . PE R C E N TA G E OF C era titis capitata IN FE STA T IO N (La te -r ip en in g v a r ie ty C am piel)

Place DateNumber of

fruits harvested

Number of fruits

infested°i° Remarks

Purchil 26/9 8 400 53 0. 63 Control area.26/9 300 18 6.00 Treatment on27/9 5 280 110 2.08 29 Aug. and 13 Sep.

2/10 7 580 93 1.223/10 10 370 122 1.174/10 7 160 83 1.187/10 7 020 89 1.268/10 7 100 98 1.38

14/10 2 820 219 7.7015/10 2 960 339 11.50

Pinos Puente 25/9 7 954 4 0.05 Experimental area.26/9 7 250 21 0.28 No treatment.27/9 ■ 1 920 4 0.2030/9 4 520 18 0.392/10 7 680 21 0.273/10 2 340 25 1.067/10 7 548 28 0.37

CONCLUSIONS

The resu lts obtained in 1973 con firm those o f 1972 and 1969 in the sense that the s te r ile - in s e c t technique is fu lly e ffec tive against C_. cap itata. The reduction in the cost o f production and the h igher e ffic ien cy o f the method o f re lea se o f re fr ig e ra ted adults represen t a substantial p ro g ress in the p ra c tica l application o f the technique on a la rg e sca le .

R E F E R E N C E S

[ 1] MELLADO, L ., CABALLERO, F., ARROYO, М., JIMENEZ, A ., "Ensayos sobre erradicación deCeratitis capitata Wied. por el método de los 'machos estériles* en la isla de Tenerife" (Experiments on the eradication of C_. capitata Wied. by the sterile-male technique on the island of Tenerife), Boletín de la Estación de Fitopatología Agrícola, no.399, INIA, Madrid (1966).

[2 ] ARROYO, М ., MELLADO, L. , JIMENEZ, A ., ROS, P . , "Lucha biológica contra Ceratitis capitata por el método de 'machos estériles'" (Biological control of C. Capitata by the sterile-male technique), Progress Report 1971, INIA, Madrid.

[3 ] ARROYO, М ., JIMENEZ, A ., MELLADO, L ., CABALLERO, F ., "Aplicación de isótopos radiactivos a la investigación de métodos sobre lucha biológica contra plagas (Application of radioisotopes in the study of methods of biological control of pests),

I. Ensayos sobre marcado de adultos de Ceratitis capitata con P-32 (Experiments on 32P-labelling of C. capitata adults).

II. Ensayos sobre marcado de larvas de Ceratitis capitata con P-32 (Experiments on 32P-labelling of C. capitata larvae).

IAE A -PL-582/20 65

I I I . O b tención de m achos estériles de C era titis cap ita ta m ed ian te la irrad iac ión de sus pupas con rayos

gam m a (Production o f C_. cap ita ta s te r ile m ales by gam m a irrad iation o f p u p ae ).

IV . E fectos de las rad iaciones gam m a sobre pupas de C era titis cap ita ta en función d e l fracc ion am ien to

de la dosis de irrad iac ión (E ffec ts o f gam m a rad ia tion on C_. cap ita ta pupae as a function o f irrad iation

dose frac tion a tion ).

V . E fectos de la rad iac ión gam m a sobre pupas de C era titis cap ita ta p rev iam en te m arcadas con P -3 2 ”

(E ffec ts o f gam m a rad ia tion on C . cap itata pupae la b e lled in advance w ith 32P),

Boletín de la Estación de F itop a to lo g ía A g r íc o la , V o l .X X V II I , no. 388-392, IN IA , M adrid (1965 ).

[ 4 ] M ELLADO, L. , ARROYO, М . , JIM ENEZ, A . , CABALLERO, F . , "Ensayos sobre errad icac ión de C era titis

cap ita ta W ied . por e l m étodo de los 'm achos estériles* en la isla de T e n e r ife . Progresos rea lizados

durante e l año 1967" (Experim ents on the e rad ica tion o f C_. cap ita ta W ied . by the s te r ile -m a le techn ique

on the island o f T e n e r ife . Progress report 1967), Boletín de la Estación de F itop a to lo g ía A g r íc o la ,

V o l . X X X , IN IA , M adrid (1967 -68 ).

[ 5 ] ARRO YO , М . , M ELLADO, L . , JIM ENEZ, A . , CABALLERO, F . , " In flu en c ia en la puesta de Ceratitis

cap ita ta W ied . de distintas d ietas a lim en tic ia s " (In flu en ce o f d iffe ren t diets on the ov ipos ition o f

C . cap ita ta W ie d . ) , Boletín de la Estación de F itop a to lo g ía A g r íc o la , V o l .X X X , IN IA , M adrid (1967-68 ).

[ 6] M ELLADO, L . , ARROYO, M . , JIM ENEZ, A . , CABALLERO, F . , "Ensayos sobre errad icac ión de C era titis

cap ita ta W ied . por e l m étodo de 'm achos es té r iles ’ en la isla de T e n e r ife . Progresos rea lizados en 1968”

(Experim ents on the e rad ica tion o f C . cap ita ta W ied . by the s te r ile -m a le techn ique on the island o f

T e n e r i fe . Progress report 1968), Boletín de P a to lo g ía V e g e ta l y E n tom olog ía A g r íc o la , V o l .X X X I,

IN IA , M adrid (1969 ).

[ 7 ] M ELLAD O , L. , ARRO YO , М . , JIM ENEZ, A . , "W ork at the Instituto N a c ion a l de Investigaciones

A gron óm icas” , S te r ile -M a le T ech n iqu e for Con tro l o f Fruit F lies (P roc . Panel V ien n a , 1969), IA E A ,

V ienna (1970) p . 90.

[ 8 ] M ELLAD O , L . , NAD EL, D .J . , ARROYO, М . , JIM ENEZ, A . , "M ed iterranean fru it f ly suppression

experim en t on the Spanish m ain land in 1969” , S te r ile -M a le T ech n iqu e fo r Con tro l o f Fruit F lies (P roc .

Panel V ien n a , 1969), IA E A , V ienna (1970) 91.

[ 9 ] M ELLADO, L . , ’’La técn ica de m achos estériles en e l control de la m osca d e l M ed iterráneo: programas

rea lizados en España (T h e s te r ile -m a le techn ique in the con tro l o f the M editerranean fly : survey paper),

S te r ility P r in c ip le fo r Insect Con tro l or E rad ication (P ro c . Sym p. Athens, 1970), IA E A , V ienna (1971) 49.

[ 10] M ELLAD O , L . , ARROYO , M . , JIM ENEZ, A . , C A S T ILLO , E . , "Ensayos de lucha autocida contra

C era titis cap ita ta W ied . Progresos rea lizados en 1969" (Experim ents on au tocide con trol o f C . cap itata

W ied . Progress report 1969), Anales Inst. N a c , In v . Agrarias, Serie P ro tecc ión V e g e ta l n o .2 , IN IA ,

M adrid (1972 ).

[1 1 ] VA R G A S , C . , M ELLADO, L . , "E fectos d e l tratam ien to com binado de re fr ig e ra c ión e irrad iac ión gam m a

en adultos de C era titis cap ita ta W ie d " (E ffec ts o f com b ined treatm ent w ith re fr ige ra tion and gam m a

irrad iation on C era titis cap ita ta W ied . adults), Anales Inst. N a c . In v . Agrarias, Serie P rotección

V e g ta l no. 2, IN IA , M adrid (1972 ).

[1 2 ] ARROYO , М . , M ELLADO, L . , JIM ENEZ, A . , C A S T ILLO , E . , "Ensayos de lucha autocida contra

C era titis cap ita ta W ied . Progresos rea lizados en 1970" (Experim ents on au toc ide control o f C era titis

cap ita ta W ied . Progress report 1970), Anales Inst. N a c . In v . Agrarias, Serie P ro tecc ión V e g e ta l no. 2,

IN IA , M adrid (1972 ).

[1 3 ] M ELLADO, L . , ARROYO, М . , ROS, P . , "C on tro l o f C era titis cap itata W ied . by the s te r ile -m a le

techn ique in Spain ", T h e S te r ile -In sec t T ech n iqu e and its F ie ld A pp lica tion s (P ro c . Panel V ien n a , 1972),

IA E A , V ienna (1974) 63.

IAE A -PL -582/6

APPLICAT IO N OF THE STERILE-INSECT TECHNIQUE FOR CONTROL OF MEDITERRANEAN FRUIT FLIES IN ISRAEL UNDER FIELD CONDITIONS

S. S. KAMBUROV, A. YAWETZ Biological Control Institute,Citrus Marketing Board o f Israel,Rehovot, Israel

D.J. NADELInternational Atom ic Energy Agency,Vienna, Austria

Abstract

A P P L IC A T IO N OF TH E STERILE-INSECT TECH NIQ U E FOR C O N TR O L OF M EDITERRANEAN FRU IT FLIES IN

ISRAEL UNDER FIELD C O N D IT IO N S .

A la r g e -s c a le f ie ld experim en t, carried out in 1973 in Israel, em p lo y in g the s te r ile - in sec t techn ique

against th e M ed iterranean fru it f ly and conducted over a 10 000 dunam area con ta in ing c o m m erc ia l citrus

g roves , is discussed. T h e re lea se area was surrounded by a 5 0 0 -m -w id e lo w -v o lu m e (L V ) ba it spray barrier.

S te r ile f l ie s w ere re leased from theground and by a ir tw ic e w e e k ly . Results in d ica te successful con tro l o f the w ild f ly

popu lation for severa l months on ly and a c lea r suppression until July; th erea fter, w ild fe r t i le fem a les im m igra ted

in to the re lea se area through the LV barrier.

INTRO D U CTIO N

The M editerranean fru it f ly C era titis capitata (W iedemann) is regarded as a m a jo r pest of citrus and deciduous fru it in Is ra e l. In 1957, the A g ro - technical D iv is ion of the Is ra e l C itrus M arketing Board began an intensive study, under fie ld conditions, of control o f the w ild f ly population in citrus, using Malathion bait applied as a ground spray [ 1 ]. During the 1958-1959 season, experim ents w ere ca rr ied out involving spraying SIB7 and Malathion from the a ir (3 litres/dunam 1). T o obtain a m easure of the fly population and the e ffic ien cy o f the bait spray, traps containing 'S ig lu re '(U. O. P . Chem icals, USA) m ixed with 3% D D V P2 w ere placed. In 1960-1962 'M ed lu re '3 (U .O .P . Chem icals, USA) was successfu lly introduced as a m ale attractant, and the quantity of m ateria l sprayed from the a ir was reduced from 3 to 1 l it r e p er dunam. During the 1965-1966 citrus season, a lo ca lly - developed bait, 'Nasim an ' (Tam ogan, Is ra e l), m ixed with techn ica l-grade Malathion, was a ir-sp rayed using the low -vo lum e (L V ) spray method. The quantity o f spray, consisting o f 2 5% Malathion and 75% bait, applied to the citrus groves was reduced to 100 ml/dunam.

1 1 dunam = 1000 m2.

2 D D V P = 0, 0 -D im e th y l-0 -2 ,2 -d ich lo rv in y l-p h o sp h a te .

3 Later rep laced by 'T r im e d lu r e '.

67

6 8 KAM BUROV et a l.

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1973

st

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sect

re

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e ex

per

imen

tal

reg

ion

.

IA E A -P L -582/6 69

The use of this method fo r M editerranean fru it f ly control in citrus by the C itrus M arketing Board (CM B) resu lted in fru its a lm ost fr e e of infestation, ach ieved at a com parative ly low cost and by using only sm all quantities of in sectic ide per dunam. The m ost im portant feature of the method is that it presents minimum hazard to benefic ia l insects which in teract with various other citrus pests. It is, however, traditional in Is ra e l to use b io log ica l control methods fo r m ost of the im portant citrus pests by the mass rea rin g and re lea se of various benefic ia l insects and by spraying with se lec tive m ateria ls . Th is is c a rr ied out by the B io log ica l Control Institute of the CMB. The disadvantages of the use of L V spray in com m erc ia l citrus groves and the d ifficu lty of con tro lling the w ild f ly population in settlem ents by a ir - distributed bait spray, fo rced the CMB to search fo r other methods of con tro lling the fly population, to e lim inate the danger from the use of in sectic id es in com m erc ia l citrus groves in urban areas, and to reduce the w idespread use of Malathion, even at a low dosage. The s te r ile - in sec t technique can be u tilized successfu lly in urban areas and a lso in the com m erc ia l citrus and deciduous groves, reducing or elim inating insectic ide pollution.

In 1972, the International A tom ic E nergy Agency, through the United Nations D evelopm ent P rogram m e, in itiated a co -op era tive p ro jec t with the C itrus M arketing Board and the B io log ica l Control Institute of the Board to determ ine the fea s ib ility of substituting the s te r ile - in s e c t technique fo r the L V bait spray method fo r control of the M editerranean fru it fly .

In the sum m er of 1972, a p re lim in ary test of the system was made in a v illa g e about 3 600 dunams in area. S te rile m ales w ere re leased w herever citrus and other deciduous fru it hosts w ere abundant. How ever, s evere suppression of the fly population was achieved fo r only about one month because of the dense w ild f ly population in surrounding g roves and, hence, the vast im m igration of fe r t i le fem a les into the treated area in the absence o f any bait spray b a rr ie r .

TH E 1973 S T E R ILE -IN S E C T TECHNIQUE PR O JE C T

Methods and m ateria ls

The experim ents w ere designed to dem onstrate m ed fly suppression on a la rg e r sca le than in the tr ia ls of 1972. They w ere ca rr ied out in the southern coastal area of the country. The se lected area of about 10 000 dunams included com m erc ia l citrus g roves of a ll the m a jor citrus va r ie tie s , four co lle c tiv e settlem ents and w ild vegetation , including abandoned groves . The area was iso la ted on the north and south sides by 4 - 5 km of sand dunes and on the w est by the M editerranean sea, and was bordered on the east by cu ltivated fie ld s and some com m erc ia l citrus g roves (F ig . 1).

The groves outside the s te r ile - in sec t f ly re lease a rea w ere treated e ve ry 10 - 12 days with L V bait spray to suppress m igration of w ild flie s into the re lea se a rea . B e fo re the end of the picking season in A p r il, grapefru it and va lencia orange trees w ere marked in the re lea se and bordering L V spray a reas4; fru it on these trees was le ft unpicked until

4 T h e w id th o f the LV border was about 500 m ; it was sprayed in 2 5 -m -w id e swaths at 60- to 80 -m

spacings.

70 KAM BUROV et a l.

July - August to determ ine the e ffectiveness of the s te r ile - in sec t technique in these experim ents. How ever, in p ractice, a substantial amount of fru it was le ft unpicked in a ll citrus groves - both in the re lea se area and outside - because o f requ irem ents fo r fre e z in g of fru its . L a rg e quantities of these fru its outside the re lea se area w ere taken as controls.

F o r ty -s ix f ly traps (F ig . 1, Traps Nos 1-46) w ere d ispersed throughout the re lea se area to check p er iod ica lly the distribution of the re leased s te r ile flie s , and a lso outside the L V spray b a rr ie r area so as to obtain indications o f w ild f ly population fluctuations. In addition, at the end of July another 14 Nadel-type traps (F ig . 1, T raps A -N ) w ere p laced at various points in a eucalyptus grove in the north part of the re lea se area so that in form ation could be obtained on the m igration of colour-m arked (dyed) flie s re leased on the north border.

On the basis o f the fly trap data, the re lea se and b a rr ie r areas w ere sprayed tw ice with L V bait spray - at the beginning of Septem ber and the end of N ovem ber, 1972. During January - March, 1973, the f ly population was low because of the low tem peratures. Tw o weeks be fore the f ir s t re lea se of s te r ile m ales in the m iddle of A p r il, the re lea se and border a reas w ere sprayed by a ir fo r elim ination of any fe r t i le adult fem ales.

M ass -rea r in g technique

O viposition cages

The S e ibersdorf cy lin d rica l cloth oviposition cage [2 ] was replaced by a rectangu lar aluminium fram e cage (2 m x 2 m x 0.2 m), two sides of which w ere covered with a synthetic cloth screen (16 mesh/cm ), provid ing

F IG .2 . Rectangular ov ipos ition cages .

IA E A -P L -582/6 71

F IG .3 . S e lf-s ta ck in g la rva l rea rin g trays.

oviposition s ites (F ig . 2). F ro m about 250 000 adults in each cage, approxim ately one l i t r e of eggs was co llected e v e ry ten days. The rea rin g conditions w ere: tem perature 25 ± 2°C; 65 ± 5% RH and continuous lighting. The eggs w ere co llected daily and held fo r 2 days in 3- l it r e round-bottom flasks, aerated by aquarium stones, at a tem perature of 24 ± 5°C. The eggs w ere then distributed on the a r t if ic ia l d iet one day before hatching.

L a rva l medium

F o r rea rin g the la rvae, se lf-s ta ck in g trays o f fib reg la ss (0 .8 m x 0. 4 m x 0. 02 m) w ere used (F ig . 3), each tray holding about 100 000 la rvae . The cultures w ere held at 26 ± 1°C fo r the f ir s t 3 days a fte r seeding and then tran s fe rred to 20 ± 1°C and 85 ± 5% RH until fu lly developed. The mature instar la rvae jumping into water w ere co llected every 8 hours, thus keeping the number of dead pupae to a minimum.

72 KAM BURO V et a l.

Pupation and handling of pupae

Mature la rvae a re spread in a la y e r about 1 cm in depth in wooden boxes (90 cm x 60 cm x 10 cm ). Pupation takes p lace in the dark at 2 5°C and 70% RH. A fte r 48 hours, the pupae are rem oved and placed on screen - bottomed trays (90 cm x 60 cm x 2 cm), 5 lit r e s of pupae in each, and held at 20°C and 75% RH.

Irrad ia tion of pupae

The pupae a re irrad ia ted by a 60Co gamma irra d ia to r (G am m acell 220) supplied by the IAE A , at a dosage o f 9 000 rad. The irrad ia tion is perform ed on the f ir s t day of em ergence of the adult fly , in batch sequences every8 hours. A t 9 kR, the average m ale fe r t i l ity was found to be about 0. 7%. Some individual m ales may exhibit a h igher degree of fe r t ility , but not

F IG .4 . A du lt em ergen ce cab in e t.

IA E A -PL -582/6 73

g rea te r than 1. 4%. The fa il-s a fe instrument, connected to the Gam m acell, prevented any inadvertent confusion between irrad ia ted and non-irrad iated batches of pupae.5

E m ergence of irrad ia ted adults, packing and re lease

The irrad ia ted pupae a re held in iron cabinets in screen-bottom ed trays . The adults em erge in a l O m x 6 m cloth s le eve attached to the cabinets (F ig . 4). T w ice a day the flie s a re co llected from the s leeve by ch illing to 4°C, and a re stored at this tem perature fo r 2 1 / 2 days in netted trays until th e ir re lea se . One hour befo re re lease , the fl ie s a re packed into 1-gallon ventilated p lastic containers. The transportation to the re lea se area is made in insulated boxes.

The re lea se is made from the ground or from a fixed -w in g 'Cheroka S ix' plane at a height of 70 - 80 m and an a ir speed o f 70 - 75 m iles/hour. The f l ie s a re re leased fr e e ly through a 3 l/2-inch p lastic tube fixed to the flo o r o f the a irc ra ft. The fl ie s a re not harm ed by the fr e e fa ll and a fter 5 - 1 0 min com m ence their natural fligh t.

T A B L E I. NUM BER OF FL IE S RELEASED IN THE 1973 S T E R ILE - INSECT TECHNIQUE TR IA LS

RESULTS AND DISCUSSION

The w ild f ly population gen era lly declined in February and M arch.In A p r il, when s te r ile f ly re lea se starts, trapping of w ild f l ie s was c lose to ze ro . A l l fl ie s in A p r il w ere re leased from the ground, while in May and June the fl ie s w ere re leased m ostly by a ir . Some experim ents involving re lea se o f pupae by a ir w ere a lso ca rr ied out (Tab le I).

The e ffec t of s te r ile flie s on the w ild population was m easured p e r io d i­ca lly by checking sam ples o f un-picked fru it tw ice a week and by co llectin g dropped fru it fo r labora tory examination.

5 Th is instrument was constructed in th e IA E A Laboratories, Seibersdorf.

I U

IV

74 KAM BURO V et a l.

untH о ш ш 1 imm¿

FIG

.5.

Per

cen

t m

edfly

in

fest

atio

n

in sa

mp

les

from

th

e re

lea

se,

LV

bait

sp

ray

and

un

trea

ted

are

as.

IA E A -P L -582/6 75

T A B L E II. IN F E S TA T IO N O F F R U IT V A R IE T IE S IN TH E BARRIER A R E A ON SPE C IF IC DATES

P la ce V arie ty

In festation (<7o)

13 July 1973 30 July 1973

Gvar A m G rapefru it 8 .7 27 .73

Orange (v a le n c ia ) - 11.71

M avk iym Grapefru it - 8 .82

Orange (v a le n c ia ) 14.2 65.35

Yad M ordecha i G rapefru it - 11.43

Beginning in May, the population o f w ild f l ie s outside the L V bait spray border increased ; hundreds o f flie s developing on sour orange and other citrus fru its w ere trapped weekly. In the f ir s t ten days of June, thousands of in fested fru its in the control area fe ll . In the m iddle of June, fl ie s w ere captured in the L V border traps, and at the end of this month about 1% in festation was noted in sam ples co llected from Z ik im in the re lea se area (591 fru its ).

A t the same time, a ll sam ples from K arm iyya and Yad M ordechai in the re lea se area (va lencia and grapefru it) w ere clean. During the f ir s t ten days o f July in K arm iyya , out of 767 grapefru it co llected , 1. 6% w ere in fested. In the m iddle of the same month, 8. 5% infested grapefru it w ere found in Yad M ordechai (out of 11 430 fru its sampled) and 5% of valencia oranges from Z ik im w ere in fested in a sam ple of 4 365 fru its .

F rom data co llected on 30 July, 1973, the damage was found to have increased toâbout 34 - 39% in the whole re lea se area (F ig . 5). On the sam ee day, hundreds of fru its from the L V bait spray area w ere co llected and checked. H igher in festation was found in the M avkiym citrus groves, which a re nearest to the re lea se area (Tab le II).

It was c lea r that the L V spray s trip of 500 m width was not su fficien t to p resen t a b a rr ie r to the la rge w ild f ly population, and many fe r t i le fem a les penetrated into the re lea se area. P robab ly m ost of the w ild flie s in filtra ted through the eucalyptus groves in the north part o f the re lease area where the highest in festation was found and where the distance between the b a rr ie r and the re lea se area was only 120 m. Since the w ild f ly popula­tion was increas ing in the re lea se area and the L V spray b a rr ie r had proved ine ffic ien t, re lea se of s te r ile f l ie s was stopped at the end of July.

E xperim ents w ere made to identify the m igration of w ild f l ie s to the re lea se area on the north boundary. Nadel traps w ere placed throughout the eucalyptus groves (traps A - N, F ig . 1). Eight hundred thousand green - coloured flie s w ere re leased from the ground at the M avuiym border line; the marked f l ie s w ere trapped a fter six days in la rge numbers, not only in the traps in the eucalyptus grove, but a lso in traps placed in Z ik im , K arm iyya and Yad M ordechai and to the south sand dune border (traps Nos 10 and 11). One week la ter, eight hundred thousand orange-co loured fl ie s w ere re leased from the ground in the same p lace, one day a fter

76 KAM BUROV e t a l.

application o f L V spray. These flie s w ere caught in the Nadel traps in the eucalyptus g roves and a lso in traps Nos 10, 11, 21, 25 and 36. These two experim ents dem onstrate the m igration of w ild f l ie s across the en tire re lease area from the north, in the wind d irection .

The resu lts of this experim ent and those of the previous yea r indicate the d ifficu lties in the use of s te r ile f l ie s fo r con tro lling the w ild f ly popula­tion in sm all areas, even when re lease starts at the tim e of natural decline in the w ild f ly population. Isolation of such areas with L V or ground sprays is feas ib le provided that wide areas surrounding the re lea se area a re treated and the w ild f l ie s a re com plete ly controlled, as in the cen tra lly -o rgan ized f ly control system in operation in Is ra e l during the citrus season. Under our lo ca l conditions, it is quite d ifficu lt to use the s te r ile - in s e c t technique in la te spring and sum m er because it would entail the stoppage of chem ical fly control in the citrus areas. However, good chances fo r successfu l fly control with s te r ile fl ie s could be ach ieved in la rge areas which are m ore o r less naturally iso la ted by re leas in g the irrad ia ted flie s in the autumn, when the w ild f ly population in citrus groves throughout the country fa lls under L V bait spray control.

R E F E R E N C E S

[ 1 ] COHEN, I . , COHEN, J . , C en tra lly organ ized con tro l o f the M ed iterranean fru it f ly ( C era titis cap ita ta

W ie d . ) in citrus g roves in Israel, A g ro tech n ica l D iv is ion , Citrus M arketin g Board o f Israel (1967 ).

[2 ] N AD E L, D . J . , "Current m ass-rearing techniques for the M ed iterranean fru it f l y ” , S te r ile -M a le Tech n iqu e

for C on tro l o f Fruit F lies (P ro c . Panel V ienna, 1969), IA E A , V ien n a (1 9 7 0 ) 13.

IA E A -PL -582/7

APPLICATIO N OF SIT ON THE EUROPEAN CHERRY FRUIT F L Y , Rhagoletis cerasi L. , IN NORTHWEST SWITZERLAND

E.F. BOLLER, U. REMUND Swiss Federal Research Station for Arboriculture, Viticulture and Horticulture,

Wadenswil, Switzerland

Abstract

A P P L IC A T IO N OF S IT O N TH E EUROPEAN CHERRY FRU IT F LY , Rhagoletis cerasi L. , IN N O RTH W EST

S W ITZE R LA N D .

T h e procedures used for rearin g , s te r iliz in g , m ark ing and re lease o f Rhagoletis cerasi L. are re v iew ed .

A sm a ll-s ca le con trol p rogram m e was started in 1973 in two p ilo t orchards, to b e expanded in 1974, in

order to in ves tig a te the fe a s ib ility o f e rad ica tin g R. cerasi b y S IT . T h e results ach ieved so far and the

problem s to b e so lved are discussed b r ie fly .

1. INTRO D U CTIO N

In 1969 suitable experim ental orchards w ere se lected in the cherry producing cen tre o f northwestern Sw itzerland and eco log ica l and behavioural studies w e re c a rr ied out in anticipation of a future re lea se program m e [ 1 , 2 ] . Density maps w ere established in th ree potential re lea se areas in 1969,1970 and 1971 and a joint Sw iss-Austrian co llection campaign was put in operation in 1971 in o rd e r to p rovide the n ecessary f ly m ateria l fo r fie ld re lea ses . In 1972, a f irs t re lea se p rogram m e involving some 600 ch erry tre e s and 180 000 flie s was ca rr ied out in ord er to study the techniques developed in the labora tory and the lo g is t ic problem s connected with handling la rg e r numbers o f f lie s . The experim ent indicated that the in itiation o f an actual control p rogram m e aim ing at the eradication o f the target species was techn ica lly feas ib le . H ow ever, unexpected eco log ica l factors (heavy dam age to the cherry crop due to late fros ts and subsequent change o f the d isp ers ive behaviour of the f lie s ) pointed to the necessity o f ca rry in g out the pilot studies in s e ve ra l sm all orchards ra th er than in the 50-ha area p rev iou sly se lec ted fo r the con tro l p rogram m e [ 3] .

Tw o sm all orchards (15 and 30 trees resp ec tiv e ly ) w ere th e re fo re chosen fo r the control program m e in itiated in 1973 and a th ird orchard (50 tre e s ) was prepared fo r 1974 by suppressing the w ild population by means o f a m ass-app lication o f v isua l traps [4 , 5] .

The ob jective of the investigations in p rogress is to prove the feas ib ility o f erad icating Rhagoletis ce ra s i on a sm a ll sca le under the spec ific conditions o f Sw itzerland as a m odel fo r la rg e r operations in the future.

2. PRO D U CTIO N AND P R E P A R A T IO N OF S TE R ILE FL IE S

2 .1 . R earing

Although the current re lea se program m e is based on fie ld -co lle c ted m ateria l by adopting the approach suggested by the IA E A [1 , 6 ], research

7 7

7 8 BOLLER and REMUND

TABLE I. COMPOSITION OF DIET G6D4 IN PER CENT

Nutrients

Crude sugar

Brewer's yeast

W heat germ

W ater

Bulking agents

Paper pulp (d ry )

G elgard M

Other ingred ients

C h olestero l

C h o lin e ch lo rid e

Wesson's salt m ixtu re

A sco rb ic ac id

P rop ion ic ac id

C itr ic ac id

T o ta l

1 0 . 0

1 0 . 0

7.5

55. 9

13.0

1 . 0

0.35

0.07

0.18

0.8

0.4

0.8

100. 0 pH 4. 0 - 4.1

e ffo rts have been concentrated on the developm ent o f a suitable m ass- rea r in g system fo r the species under labora tory conditions.

The present rea r in g system (described in deta il e lsew here: Katsoyannos and B o ile r , in preparation ) has, at present, an output of som e 20 000 eggs per day and reaches a re c o v e ry ra te o f about 20% (maximum 58%) from the egg to the adult stage. Because o f the pupal diapause only two generations per yea r can be produced. Th is phenomenon has, on the other hand, the advantage that pupae can be produced and stockpiled throughout the yea r with re la t iv e ly low investm ents with rega rd to rea rin g space and manpower.

The com position o f the la rva l diet used at present at our laboratory is g iven in T ab le I.

2 .2 . S teriliza tion , m arking and transportation

F resh ly em erged f l ie s a re tran s fe rred da ily to holding containers (30 -litre cy lin ders , polyethylene) at 24°C, 60 -70% RH and 15 lx on a dry diet consisting of 99.9% sugar and 0.1% Dysprosium ch loride that is prepared as a thick s lu rry , applied to f i l t e r paper s trips and dried befo re application. The low light intensity a llow s a norm al feeding activ ity but prevents m ating. The carbohydrate diet slows down the developm ent o f the ova ries and provides at the sam e tim e the m arking substance fo r the neutron activation analysis of recaptured flie s that do not show a distinct v isu a l m arker. A t the age of 2 days the flie s a re tran s fe rred to a cold

IA E A -P L -582/7 7 9

room (0°C) and ch illed , and th e ir numbers determ ined by weight. Batches o f 2000 flie s are p rocessed in a sim ple dev ice that d istributes 5 sam ples of 400 flie s into ch illed g lass bottles (20 m l volum e) with a p lastic snap-cover. These bottles a re transported in a cooling box to the irrad ia tion source (type SU LZE R , poo l-sou rce with eight 60Co bars ) and irrad ia ted with 10 ± 0 .5 krad (d o se -ra te 300 krad/hour). A fte r irrad ia tion the flie s are tran s fe rred in the cooling box to a low -tem pera tu re room (15°C), marked with a fluorescen t aeroso l spray (K R Y LO N ; Remund and Zehnder, in preparation ) and poured back into the holding containers. They a re now given the standard dry sugar-prote in diet (sugar: yeast hydrolysate 4:1) and held under low ligh t in tensity until re leased in the fie ld .

1400-Ez

SО

Iо

1000

800

6 00-

400

10 AGE INDAYS

•-99о = d f

100-,>-

g 80 шCLОCE Q.Ь Xо

6 0 -

20 -

2 4 6 8 10 AGE IN DAYS

FIG . 1. In flu en ce o f a g e on th ree f l ig h t param eters (d is tance flow n in 24 hours, number o f in d iv idu a l fligh ts

and flig h t p ropensity ). A verages o f 50 values.

80 BOLLER and REMUND

TIME (Min)

О AGE IN DAYS

FIG . 2 . In flu en ce o f a ge on m ating a c t iv ity expressed in terms o f m ating speed and percen tage o f form ed

pairs w ith in a 180-m in observation period . 100 flies o f both sexes used for each experim en t.

F lie s that have reached an age o f 4 - 7 days a re transported tw ice a week under exclusion o f light in th e ir holding containers to the re lea se sites w here the containers a re opened and exposed to sunlight. A fte r 10 - 15 min som e 90% o f the fl ie s have le ft th e ir containers and flown to the cherry trees .

2.3. O ptim alizing the age of flie s

W hereas a quality control p rogram m e m easures the im pact o f rea rin g procedures on the individual components o f the quality [ 7 ] , investigations w e re ca rr ied out to find the optim al age o f the re leased f l ie s with regard to d isp ersa l, host finding and m ating a c tiv it ie s . F ligh t m ill studies revea led that m a les and fem a les reach th e ir optim al fligh t capacity and flight propensity a fte r 6 - 8 days (F i g . l ) . S im ila r observations w ere made with resp ec t to m ating speed as an index fo r the mating propensity o f m ales and fem ales o f a given age group (F i g . 2). These two aspects indicated that the im m ediate im pact of the s te r ile flie s on the w ild population could be increased by holding the f l ie s back in the labora tory fo r at least 4 days. Th is seem ed to be feas ib le as no extra w ork was involved and the holding containers requ ired only m in im al labora tory space.

IA E A -P L - 582/7 81

3 .1 . The re lea se sites

On the basis o f experience gained in 1972 th ree new re lea se sites w ere se lec ted in the same gen era l a rea w here w e had worked fo r severa l y ea rs .One orchard with 30 ch erry tre e s was com plete ly surrounded by dense fo re s t , the second orchard consisted o f 15 ch erry tre e s which w ere separated from other orchards on two sides by dense fo re s t and on the other sides by open fie ld s (the distance to the c losest orchard was 200 m ). Th is la tter situation was included in our experim ents in ord er to investiga te im m igration and em igration o f f l ie s to and from the experim enta l orchard . A third site to be included in 1974 was a lso com plete ly surrounded by fo re s t and contained a m ixed orchard o f som e 50 ch erry and 50 apple and plum tre e s . None of the th ree orchards had re c e iv ed in sectic ida l treatm ents fo r seve ra l yea rs and average in festation le v e ls reported by the owners w ere medium to s eve re . H ow ever, due to the pecu liar situation in 1972 [ 3] the density o f the natural populations had dropped d rastica lly because b ird s had rem oved m ost o f the few ch erries that had survived the late fros t spe lls .

3.2. R e lease schedule

On the basis o f our fo recasts o f beginning o f fligh t and of the peak of the ch erry harvest [ 8 ] as w e ll as on em ergence data and fligh t curves o f the ta rget spec ies , we re leased s te r ile f l ie s in 3 - 4 day in terva ls and with increas ing rates starting one week b e fo re the f ir s t f lie s appeared in nature and ending 10 days b e fo re harvest. During this period a total o f 73 000 flie s was re leased in both experim enta l orchards and m onitored by seven visual traps that w ere checked tw ice a week throughout the en tire flight period .

3.3. Results

6.5% of the re lea sed flie s w ere recaptured. M ore than 95% o f these f lie s exhibited distinct flu orescen t m arkers and the rem ainder had to be analysed by means o f the neutron activation technique. W ith the exception o f f iv e doubtful cases where the autoradiographic method did not produce re lia b le identification o f marked flie s , no w ild flie s could be d iscovered . H ow ever, it was assumed that a v e ry low w ild population was present because an average number o f 0.16 flie s per trap was observed in one check orchard w here an intensive trapping program m e had been ca rr ied out (50 tre e s , 289 traps).

No m arked flies w e re observed to leave the experim ental orchards and to d isp erse o ver the open fie ld s . The period ica l incubation o f eggs d issected from ch e rr ie s showed that a ll eggs w ere fu lly s te r ile and no in festation of the crop could be detected at harvest tim e. In the check orchards the a ve rage in festation was 2.0% (range 0 - 8%).

3. FIELD RELEASES

4. CONCLUSIONS

The re leases ca rr ied out in the past two years have shown that the methods applied in the s te r iliza tion , m arking and re lea se o f the cherry fru it

8 2 BOLLER and REMUND

fly have reached a sa tis factory le v e l and make it possib le to in itiate sm a ll- sca le control experim ents. D espite the prom ising resu lts ach ieved in 1973 because o f favourab le conditions (v e ry low population densities of the ta rget sp ec ies ) it is n ecessary to continue the p ilot studies under various eco log ica l conditions b e fo re the fea s ib ility o f an eradication can be determ ined.

In addition, resea rch has to continue in two d irections: M ass-rea rin g (including quality con tro l) and host-race situation o f Rhagoletis ce ras i.Although considerab le p rogress has been made in the developm ent o f a su itable m ass -rea r in g system , further im provem ents a re necessary in ord er to maintain a high quality and genetic va r ia b ility o f the rea red insects that have to rep lace the fie ld -co lle c ted m ateria l used at presen t. Popu lation - genetic studies in p rogress [9 , 10] have to g ive us a c lea r answer in the near future as to whether the host-race o f R . c e ra s i associated with honey­suckle ( Lon icera spp. ) should be considered a potential source fo r r e ­in festations or a distinct species that does not in terbreed with the true ch erry fru it f l ie s in nature.

A C K N O W L E D G E M E N T S

Many thanks are due to the sta ff o f this laboratory — espec ia lly to V . Katsoyannos who made these studies possib le . The authors a lso extend th e ir thanks to D r. K . Russ fo r his collaboration in the jo in t collection cam paigns fo r Rhagoletis m a ter ia l in east Austria .

R E F E R E N C E S

[ 1 ] BOLLER, E. e t a l . , E conom ic im portance o f R hagoletis cerasi L . , the fe a s ib ility o f g en e t ic con tro l and

resu lting research prob lem s, Entom ophaga (1970) 305.

[ 2 ] BOLLER, E. F. , H A IS C H , A . , PROKOPY, R. J. , ''S te r ile insect re lea se m ethod against Rhagoletis cerasi L. :

preparatory e c o lo g ic a l and behav iou ra l studies", S te r ility p r in c ip le for Insect C on tro l or Eradication,

(P ro c . S ym p. A thens, 1970), IA E A , V ienna (1971 ) 77.

[ 3 ] BOLLER, E. F. , "Status o f the s te r ile - in sec t re lease m ethod against th e cherry fru it f ly (Rhagoletis

ceras i L . ) in northwest S w itz e r la n d ", T h e S te r ile -In sec t Tech n iqu e and its F ie ld A pp lica tions (Proc.

Panel V ien n a , 1972), IA E A , V ien n a (1974 ) 1.

[ 4 ] PRO KO PY, R .J . , BOLLER, E. F . , Response o f European cherry fru it f lie s to coloured rectang les, J. Econ.

Entom ol. 64 (1971) 1444.

[ 5 ] RUSS, K . e t a l . , D eve lop m en t and app lica tion o f visual traps for m on ito rin g and con tro l o f populations

o f Rhagoletis cerasi L . , Entom ophaga 18 (1913) 103.

[ 6 ] IN T E R N A T IO N A L A T O M IC ENERGY A G E N C Y , Radiation , Radioisotopes and Rearing M ethods in the

C on tro l o f Insect Pests, (P roc. Panel T e l A v iv , 1966), IA E A , V ienna (1968) 143.

[ 7 ] BOLLER, E. , B ehaviora l aspects o f m ass-rearing o f insects, Entom ophaga 17 (1972) 9.

[ 8 ] REM UND , U . , BOLLER, E. , Neuerungen im schw eizeriscnen Prognosewesen fur d ie K irs c h e n flie g e ,

S ch w e iz . Z . O bst-W einbau 107 (1971) 183.

[ 9 ] BOLLER, E. F . , BUSH, G . L . , E vidence for g en e t ic va r ia tion in populations o f the European cherry

fru it f ly , Rhagoletis cerasi L. (D ip tera : T ep h r it id a e ) based on p h ys io lo g ica l param eters and

hyb rid iza tion experim ents, Ent. Exp. & A p p l. 17 (1974 ) 279.

[1 0 ] BUSH, G .L . , BOLLER, E. F . , G en e tic distance and evo lu tion ary relationships in th e Rhagoletis cerasi

group, Ent. Exp. & A p p l. (subm itted ).

IA E A -PL -582/8

SM ALL -SC ALE F IELD EXPERIMENTS ON STERILE-INSECT CONTROL OF THE ONION F L Y , Hylem.ya antigua (Meigen)*

J. THEUNISSEN, M. LOOS JES,J. Ph. W. NOORDINK, J. NOORLANDER,J. TICHELER

Institute for Phytopathological Research,Wageningen, The Netherlands

Abstract

S M A LL-S C A LE FIELD EXPERIMENTS O N STER ILE -INSECT C O N TR O L OF TH E O N IO N FLY , H y lem ya antigua

(M E IG EN ).

D uring th ree con secu tive years sm a ll-s ca le f ie ld trials w e re carried out in order to ch eck th e fe a s ib ility

o f the s te r ile - in sec t techn ique as a possib le con trol m ethod for th e on ion f ly , H y lem ya antigua (M e ig e n ).

Results, so far analysed, suggest a considerab le reduction o f the in it ia l on ion f ly popu lation , the poss ib ility

to attain a sa tis factory le v e l o f s te r ile fl ie s in th e popu lation , a norm al percen tage o f m ated s te r ile fem a les ,

a norm al su scep tib ility o f the s te r ile f lies to insect fungus in fec tion and a decreasing number o f in fested onion

plants per hectare .

INTRO D U C TIO N

Labora tory resea rch on the poss ib ility to use the s te r ile - in sec t technique (S IT ) to control the onion fly , Hylem ya antigua (M eigen ), led to a se r ies of four sm a ll-s ca le tr ia ls on onion fie lds of which three have been ca rr ied out. As a resu lt o f p re lim in ary w ork [1 , 2 ], research topics included: p roperties o f the la rva l medium [ 3 ] , pupation, production and storage of pupae, egg production and rea rin g e ffic ien cy [ 4 ] , irrad ia tion , com petitiveness of s te r iliz e d fl ie s and the use of rad io isotopes [ 5 ] , h istopathological e ffects o f irrad ia tion [ 6 ] , sperm atogenesis and oogenesis [7 , 8 ], cytogenetics [9 -1 1 ], m arking, d ispersa l, trapping methods and population dynam ics [ 12 ] , and com puter simulation m odels [ 13-15 ] .

Some resu lts of the f ir s t two fie ld tr ia ls w ere d iscussed e a r lie r [16] and recen tly a genera l rev iew on the genetic control o f the onion fly was published [17] . A s to the present situation in s te r ile - in sec t p ro jec ts , Lindquist [18] published a rev iew on the p rogress made during the past few -yea rs . The present paper describes som e resu lts o f the f ir s t th ree sm a ll-s ca le fie ld experim ents in the Netherlands.

METHODS

During the third of the current s e r ies of sm a ll-s ca le fie ld tr ia ls , fourth- generation o ffsp rin g o f fie ld -co lle c ted onion fly pupae w ere used. The methods used have been described b e fo re [ 16 ] and only m inor changes have

* T h is p ro jec t has been supported by Euratom and the In ternational A to m ic Energy A g e n c y (IA E A

Research Contract N o . 676/RB).

83

84 THEUNISSEN et a l.

been made. The pupae w ere irrad ia ted with 3 kR o f gamma rays from a 60Co source (1.323 M eV , T^ = 5. 25 yea rs ; 120000 Ci; d ose-ra te 900 R/m in).

In ord er to mark the s te r ile flie s in the fie ld with a colour, the irrad ia ted pupae w ere p laced under a thin la ye r o f a fluorescen t powder, Radglo, in the fo llow ing way. In a tray 25 cm X 25 cm X 10 cm , in the bottom o f which sm all holes have been d r illed , a p iece o f f i l t e r paper is covered with a thin la y e r o f wet sand. About 10 000 irrad ia ted pupae a re m ixed with m oist v e rm icu lite and poured on the wet sand. The pupae a re covered with a thick la y e r o f dry sand to fo rc e the em erging pupae to use th e ir ptilinum w e ll, in o rd er to pick up the stain. The fluorescen t powder is applied in a thin la y e r on the surface o f the sand. Th is vu lnerable la ye r is protected by a thin cover o f verm icu lite , which is s ieved on the powder, and the verm icu lite is covered with a thin la y e r of dry sand.

Each tray was covered by an inclined plate to keep the contents dry.As a resu lt "a l l w ea ther" functioning o f the tray was secured while the em erged f l ie s could lea ve it fre e ly .

W eek ly, ten trays w ere used to re lea se the s te r iliz ed pupae. F o r six consecutive weeks a d ifferen t colour was used b e fo re an a lready applied colour was re-u sed .

The re lea se schedule was s im p ler than that of the two preceding fie ld t r ia ls . The idea o f fo llow in g the em ergence of the w ild population and coverin g it with a m ore o r le s s constant ra tio o f s te r ile f l ie s was abandoned in favour o f the w eekly re lea se o f a constant number o f s te r ile flie s . The population developm ent o f the onion fly in the fie ld seem s to be too ir re g u la r and unpredictable to base any re lea se system on it. When a constant number o f s te r ile flie s is re leased the developm ent o f the w ild population is not considered . During the firs t weeks re lea ses took p lace by putting two trays between p la tform s some 1 0 - 1 5 cm above the le v e l o f the so il of the onion fie ld to protect the pupae from m ice . H ow ever, when weather conditions w ere hot, the tem perature in the trays rose too much. M oreo ve r , this way o f gradual re lea se attracted increasing numbers o f b ird s . In spite of the protection m easures taken, b ird predation was high on som e groups. Fu rther re lea ses took p lace by digging the trays in one o r two groups in the so il at the m argin o f the onion fie ld or putting the trays between rows o f potato plants in an adjacent fie ld . Only the la tte r method stopped b ird predation e ffe c tiv e ly .

In preced ing yea rs , during the f ir s t fligh t, the s te r ile f l ie s w ere re lea sed on the fie ld where the w ild flie s could be expected to em erge, i . e . the onion fie ld o f the y ea r b e fo re . During the second fligh t, re lea ses w ere ca rr ied out on the new onion fie ld . In 1973, a ll re leases took p lace on the present onion fie ld to determ ine whether such a s im p lified procedure could be used o r not. E ve ry week about 100 000 pupae, y ie ld ing an average number o f 84 000 flie s , w ere re leased .

M ating o f the fem ales was determ ined by checking the contents o f the sperm atheca.

In 1973, in festation of plants on both the experim ental fie ld and a check plot was checked w eek ly. Certain rows w ere se lected to cove r the experim ental and untreated area, represen ting 3.1% and 2.8% o f the areas. In fested plants w ere m arked with a lab e l near the plant and, b e fo re the harvest, so il sam ples w e re taken w here labels indicated in fested plants to estim ate the over-w in ter in g population o f pupae. During the fie ld experi-

IA E A -PL -582/8 85

ments the sam pled a reas rep resen ted the fo llow ing percentages o f the experim enta l fie ld s : (1970) 0 .5 ; (1971 )0 .2 ; (1972) 1.6; (1973) 3.1.

RESULTS

Some resu lts of the firs t two fie ld experim ents have a lready been discussed [ 16] . F o r com parison the y ea rs o f these experim ents are included in the data presented here.

During 1970, 1971, 1972 and 1973 the output o f the rea r in g was increased considerab ly due to a steady im provem ent in rea r in g methods and ava ilab le fa c ilit ie s (T a b le I ).

In 1973 the numbers o f re leased pupae w ere in creased sign ificantly com pared with those o f previous y ea rs . Th is resu lted in a high le v e l of s te r il ity during the experim ent. The quality of the pupae and the p reva ilin g w eather conditions perm itted a high percentage of s te r ile flie s to em erge.As a resu lt o f the increased numbers o f re leased s te r ile f l ie s (T ab le II) the percentage of s te r ile flie s in the population was h igher in 1973 than in previous years (F ig . 1). In genera l, a high le v e l o f s te r il ity in the population was obtained.

Th e percen tage o f egg s te r ility in 1973 was d ifficu lt to determ ine owing to the low number of eggs produced. The numbers o f trapped fe r t i le fem ales w e re low and many died without ovipositing in the laboratory cages. The lim ited number of egg batches used to determ ine the figu res caused considerab le v a r ia b il ity . M oreo ve r , a few fe r t ile , a lready mated im m igra tin g fem a les could have a d isproportiona lly negative influence on the egg s te r ility (F ig . 2 ).

During the th ree experim ents the percen tage o f mated fem a les was scored in o rd er to com pare the mating o f the s te r ile fem ales with that of the fe r t i le ones (F ig .3 ). In 1973, the numbers o f su rviv ing fe r t i le fem a les w e re often too low to draw any conclusions. As a resu lt o f fungus infestation som etim es even s te r ile fem a les did not su rvive in su fficien t numbers.

In 1971, fungus ep izootics w ere observed in the fie ld (F ig . 4, 1971).The fungus was an Entornophthora sp. A m arked d iscrepancy between the percen tages of s te r ile fl ie s and s te r ile eggs (F ig s 1 and 2) suggested that p re fe ren tia l in festation o f s te r ile flie s could be a possib le cause [ 16] . To prevent such a presum ed p re fe ren tia l in festation , re lea se methods w ere

T A B L E I. AVERAG E W E E K L Y PRO D U CTIO N OF PU PA E DURING M ASS-REAR IN G PERIOD

1970 25 000

1971 50 000

1972 100 000

1973 to о о 000

1974

ооm

000a

a Estim ated.

8 6 THEUNISSEN et a l.

TABLE II. SUMMARY OF RESULTS

Estim ated A v e ra g e w e e k ly re leaseM ean °¡o s te r ile

flie s in popu lation

°lo in fested

on ion plantso f pupae in spring Pupae F lie sa

1971 20 000 27 700 25 000 56.0 5 .22

1972 17 000 50 500 32 400 67 .8 0 .60

1973 5 000 104 800b 84 700 91.1 0 .12

1974 400

a F lies em erged in th e f ie ld from th e s te r iliz ed pupae,

k E xperim enta l area in 1973 was 1. 5 ha.

1 2 3 4 5 1 2 3 4 1 2 3 4 1 2 3 4 5 1 2 3

may June july august sept

FIG . 1. Percen tages o f s te r ile f lies in popu lation .

IAE A -PL -582/8 87

1 2 3 4 5 1 2 3 4 1 2 3 4 1 2 3 4 5 1 2 3

may june July august sept

FIG . 2. Percen tages o f s te r ile eggs produced b y trapped fem a les . Figures based on 20 eggs or less have

b een om itted .

changed accord ing ly . T h e re fo re , the ra te o f insect fungus in festation in the trapped, liv in g fem a les was recorded during the next yea rs (F ig . 4).In 1972 and 1973, the fungus in fection in trapped fem ales did not show any p re fe ren ce fo r s te r ile o r fe r t i le fem ales.

The number o f in fested onion plants/ha on the experim enta l fie ld s d ecreased . The a verage number of onion plants per ha was about 10®.Dam age due to onion fly in festation was estim ated during three yea rs o f fie ld t r ia ls (T ab le П).

In 1973, a check plot was availab le 800 m from the experim ental plot to check the e ffect o f a population o f fe r t ile f l ie s o f the sam e o rd e r o f magnitude without re leas in g s te r ile f l ie s . H ow ever, previous experim ents [ 12] have shown that the fly can cover distances up to 2000 m . Consequently, the average percentage o f s te r ile flies in the check plot was 59%.

8 8 THEUNISSEN et a l.

О*о■о®

оЕ

1 2 3 4 5 1 2 3 4 1 2 3 4 1 2 3 4 5 1 2 3

may june july august sept

FIG . 3 . Percen tages o f m ated fem a les in popu lation . Figures based on less than 5 ind iv iduals h ave been

om itted .

• ------• s te r ile fe r t i le

DISCUSSION

A s a resu lt o f the la rg e numbers o f w eekly re leased s te r ile fl ie s com pared with the estim ated w ild population, we expected a v e ry high s te r ile / fe r t i le ra tio during these experim ents. In fact, this ra tio proved to be lo w e r than expected. The reasons a re not c lea r . The fl ie s seem to d isp erse outside the onion fie ld and the attraction o f an onion fie ld seem s to be lim ited in its ab ility to keep la rg e numbers o f the flie s in the im m ediate surroundings. The apparent em igration o f the s te r ile population is dis - p roportiona lly disadvantageous to the e ffec t o f the s te r ile flie s when the trea ted area is sm all. In la rg e on ion-grow ing areas the d ispersa l of s te r iliz e d fl ie s should in crease the e ffect of the re lea ses .

IAE A -PL -582/8 8 9

1 2 3 4 5 1 2 3 4 1 2 3 4 1 2 3 4 5 1 2 3

may june july august sept

FIG . 4 . Percentages o f trapped fem a les in fested w ith insect fungus. Figures based on less than 5 ind ividuals

h a ve been om itted . Broken lin e in graph o f 1971 represents the p ercen tage o f s te r ile plus fe r t i le fem a les .

• ------• s te r ile 5 5 • ------• fe r t i le 2 ?

A possib le explanation fo r the low egg s te r ility in 1973 is the im m igra tion o f a lready fe r t i l iz e d fem ales from priva te gardens. When the low loca l population o f fe r t i le fem a les is e ffe c t iv e ly con trolled by the re leased s te r ile s , a few im m igra tin g fe r t i l iz e d fem ales may have a considerable e ffec t on the egg s te r il ity figu res . It is possib le that such a low population density o f w ild f l ie s was reached that a few im m igrating fem ales had a considerab le in fluence on the tota l egg s te r ility without being im portant in absolute num bers. Consequently, when there is im m igra tion an in crease in the number o f re lea sed s te r ile flie s makes sense only up to a certa in le v e l when a sm all a rea is to be treated .

The percentages o f fe r t i le and s te r ile mated fem ales (F ig . 3) do not seem to d if fe r essen tia lly . In genera l, the average s te r ile fem ale trapped in the onion fie ld w ill be younger than the average im m igra tin g fe r t i le fem a le . Th is m ay be responsib le fo r the percentage o f mated s te r ile fem a les being somewhat low er than that o f the fe r t i le ones.

90 THEUNISSEN e t a l.

E p izoo tics o f insect fungus d iseases doubtless play an im portant ro le in the fie ld populations o f onion flies and other D íp tera , During the fie ld t r ia ls s e ve re outbreaks o f Entomophthora ep izootics w ere observed in the trea ted a rea . D iseased flie s show a tendency to craw l towards high points in the vegetation , e . g . flow ers and stalks o f g rass , in the last stage of pathogenesis. In fested H ies may come into the traps. B e fo re the death of the fly the fungus starts to break through the integument. A t that tim e the insect is s t i l l able to m ove but its reproductive organs, in testinal tract and m ost o f the fat and m usculature have a lready com pletely d isin tegrated [ 19] . In in sects , gen era lly one o f the f ir s t functions to be destroyed by an in fectious d isease is reproduction . So it is possib le that the fly population contains many individuals that do not reproduce.

A C K N O W L E D G E M E N T S

The authors would like to express th e ir thanks to a ll who have contributed to our p ro ject, espec ia lly M iss E . L em m ers ,M iss S . A . V oorhoeve, M r. G. Schelling and severa l students o f Dutch U n ivers ities .

R E F E R E N C E S

[ 1 ] FLUITER, H .J . de , N O O RD IN K , J. Ph. W . , TICHELER, J. H .G . , T h e on ion f ly p rob lem and the s terile

m a le techn ique, M eded . Reactor Centrum N ederland 20 (1967 ) 83.

[ 2 ] T ICHELER, J. , N O O R D IN K , J. Ph. W , , "A p p lic a tio n o f th e s te r ile -m a le techn ique on the on ion fly ,

H y lem ya antigua (M e ig . ) , in th e Netherlands. Progress rep o rt" , Rad iation , Radioisotopes and Rearing

M ethods in the C on tro l o f Insect Pests (P roc. Panel T e l A v iv , 1966), IA E A , V ienna (1968) 111.

[ 3 ] T ICHELER, J . , "R earing o f the on ion f ly , H y lem ya antigua (M e ig e n )" , S te r ility P r in c ip le for Insect

C on tro l or Eradication (P roc. Sym p. Athens, 1970), IA E A , V ienna (1971) 341.

[ 4 ] NOORLANDER, J. , unpublished.

[ 5 ] N O O R D IN K , J. Ph. W . , "Irrad ia tion , com petitiveness and th e use o f isotopes in s te r ile m a le studies w ith

th e on ion f ly , H y lem ya antigua (M e ig e n )1', S te r ility P r in c ip le for Insect C on tro l or Eradication (P roc.

S ym p. A thens, 1970), IA E A , V ienna (1971 ) 323.

[ 6 ] THEUNISSEN, J. , "R ad ia tion pa th o logy in H y lem ya antigua (M e ig e n ): outlines o f re s ea rch ", S te r ility

P r in c ip le for Insect C on tro l or Eradication (P roc. Sym p. A thens, 1970), IA E A , V ienna (1971 ) 329.

[ 7 ] THEUNISSEN, J. , Egg cham ber deve lopm en t in the on ion f ly , H y lem ya antigua (M e ig e n ) (D ip tera :

A n th om y id a e ), In t. J. Insect M orphol. Em bryol. 2 (1973 ) 87.

[ 8 ] THEUNISSEN, J . , Chrom atin transformations in th e trophocytes o f the on ion f ly , H y lem ya antigua

(M e ig e n ), during eg g cham ber d eve lop m en t (D ip tera : A n th om y id ae ), In t. J. Insect M orphol. Em bryol.

(in press).

[ 9 ] HEEMERT, C . van , Iso la tion o f a translocation h om ozygo te in the on ion f ly , H y lem ya an tigua (M e ig e n )

w ith a cy to g en ic m ethod in com b ination w ith th e d eterm ination o f the percen tage la te em bryon ic

le th a ls , Gen en Phaenen 16 (1973) 17.

[1 0 ] HEEMERT, C , van , Androgenesis in th e on ion f ly , H y lem ya antigua (M e ig e n ), dem onstrated w ith a

chrom osom al m arker, Nature (London) New B io l. 246 (1973 ) 21.

[1 1 ] W IJN A N D S -S TÁ B , K .J . A . , HEEMERT, C . van , Radiation induced s e m i-s te r ility for g en e t ic con tro l

purposes in the on ion f ly , H y lem ya antigua (M e ig e n ). Iso la tion o f s em i-s te r ile stocks and their

c y to g en e t ic a l properties, Th eo r. A p p l. G enet. 44 (in press).

[1 2 ] LOOS JES, M . , unpublished.

[1 3 ] W IJN A N D S -S TÀ B , K . J . A . , FRISSEL, M .J . , "C om pu ter s im u la tion for g e n e t ic con tro l o f th e on ion fly ,

H y lem ya antigua (M e ig e n )" , Com puter M odels and A p p lica tion o f the S te r ile -m a le T ech n iqu e (P roc .

Panel V ien n a , 1971), IA E A , V ienna (1973 ) 95.

IAE A -PL -582/8 91

[1 4 ] FRISSEL, M .J . , W IJN A N D S -S TÂ B , K . J .A . , "C om pu ter m o d e llin g o f the dynam ics o f insect popu lations” ,

Com pu ter M odels and A p p lica tio n o f the S te r ile -m a le T ech n iqu e (P roc. Pan e l, V ien n a , 1971), IA E A ,

V ienna (1973) 23.

[1 5 ] LOOSJES, М . , FRISSEL, M .J . , unpublished.

[1 6 ] TICHELER, J. , LOOSJES, M . t N O O RD IN K , J .P h .W ., NOORLANDER, J. , THEUNISSEN, J. , "F ie ld

experim ents w ith the re lea se o f s te r iliz ed on ion fl ie s H y lem ya antigua (M e ig . ) " , T h e S te r ile - in sec t

T ech n iqu e and its F ie ld App lica tion s (P roc . Panel V ienna , 1972), IA E A , V ienna (1974) 103.

[1 7 ] TH EUNISSEN , J. , LOOSJES, М . , N O O RD IN K , J .P h .W ., NOORLANDER, J. , TICHELER, J. H. G. ,

G en etic con tro l o f th e on ion f ly , H y lem ya antigua (M e ig e n ), in T h e N etherlands, Proc. 7th British

In sec tic id e and Fu ngic ide C on feren ce , 1973 (in press).

[1 8 ] L IN D Q U IS T , D . A . , R ecent advances in insect con tro l b y th e s te r ile m a le tech n iqu e, M ed ed e lin gen

Faku lte it Landbouwwetenschappen, Gent 38 (1973) 627.

[1 9 ] THEUNISSEN, J . , unpublished.

IA E A -PL -582/9

MASS REARING OF THE OLIVE FRUIT F L Y , Dacus oleae (Gmelin), AT "DEM OCRITOS"

J. A. TSITSIPISNuclear Research Center "Democritos",Aghia Paraskevi,

Attik i, Greece

Abstract

M ASS REARING OF TH E O LIVE FRU IT F LY , Dacus o le a e (G m e lin ), A T "D E M O C R ITO S ".

Production o f m ore than 4 . 5 m ill io n o l i v e fruit f ly pupae w ith in a 4 -m on th period during th e summer

and autumn o f 1973, a t an approx im ate cost o f US $ 1 per 1000 pupae, was m ade possible b y in troducing

certa in im provem ents in th e fo rm e r ly used rea rin g system . R ep lacem en t o f th e adult liqu id d ie t b y a solid

on e and less frequent changing o f th e w ater supply saved labour; b etter t im in g in the eg g c o lle c t io n im proved

h a tch ab ility . Incubation o f th e eggs in 0. 3% prop ion ic acid fo llo w ed b y their surface s te r iliza tion d rastica lly

cut down or e lim in a ted previous sporad ica lly appearing m ic ro b ia l contam inations. Most im portan t, a new

la rv a l d ie t ( T ) , w h ich is m uch easier to prepare and hand le, has doubled pupal y ie ld . A new cag in g and

e g g in g system under deve lopm en t provides a h igher egg production and requires far less labour. P re lim in ary

p rom ising results on new la rva l d iets and m od ifica tion s in the various steps o f the rearing procedu re w i l l

h op e fu lly con tribu te to a ch iev in g th e m uch low er costs needed even in a m od era te -sca le m ass-re lease

program m e.

INTRO D U C TIO N

M ass rea r in g of an insect is an unqualified te rm by its e lf. It could im ply a da ily production of anything between a few thousand and seve ra l m illion in sects . Each method fo r rea r in g insects has certa in inherent lim ita tions with rega rd to its potential, depending m ainly on ava ilab le funds. Hence, re fe ren ce to a method should include the capability o f ra is in g a certa in number of insects under spec ified conditions. Th is paper describes an im proved method o f rea r in g up to half a m illion pupae p e r week with nine labora tory technicians and the space and equipment o f the "D em ocrito s " entom ology labora tory .

The known methods fo r rea r in g the o live fru it fly have been rev iew ed by Orphanidis et a l. (1970), who dealt so le ly with la rva l a r t if ic ia l diets, and by Tzanakakis (1971). C ava llo ro and G iro lam i (1968) described a method fo r rea r in g the f ly in the labora tory . The method used at "D em ocr ito s " until 1972 fo r mass rea r in g the o liv e f ly has been described by Tzanakakis (1967), Econom opoulos and Tzanakakis (1967), and Tzanakakis et al. (1968, 1970). Since then various stages o f the procedure have been im proved .Only these im provem ents a re considered here. They a re a im ed at reducing the cost o f rea r in g , at saving space, and at am eliora tin g the quality of the flie s .

A ls o , re fe ren ce is made to prom ising resu lts from research underway.It is expected that the adoption o f such innovations w ill d ras tica lly reduce the cost o f rea r in g .

93

9 4 TS ITS IP IS

The present rea r in g system successfu lly met the requ irem ents for producing la rge numbers o f insects fo r the experim ental application o f the s te r ile - in s e c t technique in an o liv e grove in the Chalkidiki penninsula in northern G reece . Some 13 185 000 eggs w ere produced from which about 4 575 000 pupae w ere obtained from June 10th to October 3rd, 1973. The a verage egg hatchability was 66.62% (based on alm ost daily checks o f a grand tota l o f 10 419 eggs) and the adult em ergence from pupae was above 80%. The pupal y ie ld o f the la rv a l diet (T ) was 51.42% (based on hatched eggs) o r 34.25% when based on eggs la id . During the 4-month period,6 356 trays o f la rv a l d iet w ere prepared (approx. 1800 kg in weight).

Adult maintenance

The Hagen cage and oviposition substrates (Hagen et a l . , 1963) are s till in use. The No. 2 liqu id diet (Econom opoulos and Tzanakakis, 1967), o ffe red th ree tim es w eek ly to the flie s , has been rep laced by a solid diet developed in the labora tory (T s its ip is , Kontos and Gordon; unpublished data) and is supplied only once at the in itia tion o f each cage. The diet is prepared by drying the liqu id diet under vacuum at 40°C. Although fem ales feed ing on liqu id diet g ive about 20 - 30% m ore eggs than on solid diet (egg production expressed per liv in g fem a le ), the h igher m orta lity o f the fem ales on the liquid diet resu lts in an egg production (when expressed per in itia l fem a le ) that is the same or less than on the solid d iet. W ater, supplied in a sm all p lastic box with a w ick passing through the cover , is changed every 1 0 - 1 5 days instead o f 2 - 3 tim es w eek ly as was p racticed b e fo re . When starting new cages, vo lu m etr ica lly m easured pupae, ra ther than adults, a re introduced into the cagels as they a re e a s ie r to handle.

T o im prove egg hatchability, fre sh e r eggs are obtained by exchanging the egg-laden, para ffin dom es fo r new ones shortly b e fo re the onset o f scotophase (D r. H . T . G ordon 's suggestion).

Handling o f eggs and pupae

The squeeze-bottle w ater r in se r fo r the co llection o f eggs from the dom es and the s ligh tly negative pressu re applied through a Buchner funnel fo r filte r in g out the eggs have been rep laced by a spray-gun r in se r connected with the w a ter mains and a funnel with a siphon and a densely woven silk fab ric , re sp ec tiv e ly . The eggs a re tran s fe rred with a brush onto filte r paper im pregnated with 0.3% propion ic acid (f ir s t used by Manoukas, 1972) in P e t r i d ishes fo r a 24-h incubation period at 25°C. F igu re 1 indicates c lea r ly that such a concentration is not harm ful. P rob lem s of fungal contam ination o f eggs that w ere occasionally encountered with sodium benzoate w e re elim inated with the use o f propionic acid.

A fte r the 24-h incubation period , the eggs a re su r fa ce -s te r iliz ed with 2% C lo ro x ® (5 -6% sodium hypoch loride) fo r 10 m in1 (F ig . 2 shows the hatchability of C lorox-trea ted fresh ly laid eggs ). The e fficacy of s te r iliza tion was tested by asep tica lly seeding su r fa ce -s te r iliz ed eggs on an agar culture

PRESENT REARING SYSTEM

1 Egg hatch w ith C lo rox trea tm en t soon a fter deposition and 24 hours la ter was s im ila r.

IA E A -P L -5 8 2 /9 95

S soI

Ф до-

20

0.15 0.3 0.6 0.9 1.2 1.51.8 2Â 4.8PROPIONIC ACID CONCENTRATION (%)

FIG . 1. H a tch a b ility o f 0 - to 6 -h -o ld Dacus o le a e eggs incubated in p rop ion ic a c id .

100

CONTROL * 80

60-

40-

20-

0.5 1.0 2.0 4.0 8.0

CLOROX®(%)

FIG . 2. H a tch ab ility o f 0- to 6 -h -o ld Dacus o le a e eggs exposed on C lo r o x ® for 5 and 10 m in , rinsed w ith

w ater for 10 m in and incubated in 0 .3% p rop ion ic ac id .

• 5 m in ; о 10 m in .

9 6 TS ITS IP IS

medium containing enzym atic soy hydro lysate and dehydrated nutrient broth (kindly provided by D r. Haniotakis). Although th ere was some la rva l developm ent, there w e re no m icrob ia l co lon ies. A fte r s te r iliza tion , the eggs a re rinsed in tap w ater fo r 10 min; they a re then suspended in 0. 3% propion ic acid and sprinkled onto the diet instead o f being tran s fe rred with a brush as b e fo re . Surface s te r iliza tion has defin ite ly decreased diet contam ination with m icroo rgan ism s .

The eggs a re counted vo lu m etrica lly on the basis of about 45 000 eggs/m l, an a ve rage figu re reached a fte r s e ve ra l sam pling counts.

The la rva e , upon com pletion of the ir developm ent, e ither craw l out of the diet and pupate in the sawdust in which they drop, o r pupate on o r inside the diet it s e l f (30 - 60% of them ).

Upon term ination o f pupation, the diet is dumped into w ater, the rem ain ing pupae a re skimmed and then m ixed with sawdust to dry. The pupae a re s ieved to rem ove the sawdust and counted vo lu m etrica lly (about 900 pupae/10 m l). They a re then kept in open p lastic boxes and again m ixed with sawdust which is rem oved 1 -2 days b e fo re em ergence.

L a rva l rea r in g

In an attempt to im prove la rva l diet N (Tzanakakis et a l . , 1970), seve ra l m odifications w e re m ade. Medium T (Tab le I) gave the m ost prom ising resu lts , hence, it was used to produce the la rg e numbers o f f l ie s requ ired during the sum m er and autumn. A gar and roasted peanuts w ere elim inated a ltogether and the ce llu lose powder was increased by as much as 50%. The average y ie ld o f pupae per gram of diet was 2.54 (average from a total of4 575 thousand pupae) w ith a range o f 1 to 3. 96 (averages from batches o f at least 80 - 100 trays o f d iet), as com pared with an average o f 1 - 1. 5 in diet N . The pupal weight was always between 5 .5 - 6 . 5 m g, s im ila r to that fo r pupae on diet N.

The preparation o f diet T is much ea s ie r now that peanuts and agar are not included. B o ilin g and peanut grinding a re no lon ger requ ired and the granular consistency of the diet (s im ila r to that used by the IA E A entomology group) makes it e a s ie r to dispense onto trays than the pasty and fast-settin g diet N .

H ow ever, the granular diet requ ires an extra step in the ju st-described rea r in g procedure: this is the re co ve ry o f a la rge part (30 - 60%) o f the pupae from within the d iet. The quality o f such pupae was found to be as good as that o f the pupae outside the diet.

Cost o f rea rin g

Tzanakakis et a l. (1968) estim ated a cost o f US $ 13. 80 per 1000 o live fru it f ly pupae when the w eek ly f ly production was 10 000 - 15 000. A current estim ate at a 20 -fold production ra te is g iven in Tab le II. Only expendable m ateria ls and labour costs a re considered . The cost estim ation is based on an average daily pupal production o f 64 000 pupae (90 trays X 280 g/tray X X 2. 54 pupae/g), and 6. 25% of the cost is a llocated to rep lacem ent of term inating cages. A daily average production of 180 000 eggs obtained from 300 cages is seeded on 90 trays o f d iet.

IA E A -PL -582/9 97

T A B L E I. CO M PO SITIO N OF SOME L A R V A L DIETS FO R THE O LIVE F R U IT F L Y D EVE LO PE D A T "D EM O CRITO S"

N a T PSb Lc

T a p w ater 55 m l 55 m l 55 m l 100 m l

A gar ( f in e pow der, M erck ) 0 .5 g - - -

C e llu lo se powder 123,

S ch le ich er & S ch iill) 2 0 .0 g 30 .0 g 15..0 - 27. 0 g d -

Brewer's yeast (F IX ) 7 .5 g 7 .5 g ■7.5 g 1 2 .0 g

S oy hydro lysate en zym a tic

(N u tr it ion a l B ioch em ica ls Corp. ) 3 .0 g 3 .0 g 3 .0 g 4 .0 g

Roasted peanuts 6 .0 g - - -

Sucrose 2 .0 g 2 .0 g - 2 .7 5 g

O liv e o i l 2 .0 m l 2 .0 m l 2 .0 m l 2 .7 5 m l

T w een -8 0 0 .75 m l 0 .7 5 m l 0 .7 m l 1. 0 m l

Potassium sórbate (M e rck ) 0 .05 g 0 .0 5 g 0. 05 g e 0. 05 g

N ipag in

(m e th y l-p -h yd roxyb en zoa te , M erck ) 0 .2 g 0 .2 g 0 .2 g e 0 .2 g

H C l, 2N 3 .0 m l 3 .0 m l 3 .0 m l 4 .0 m l

a T Z A N A K A K IS , M .E . , ECO NO M O PO ULO S, A .P . , TS IT S IP IS , J .A .

b M A N O U K A S , A . (1972).

c M IT T LE R , T . E. , T S IT S IP IS , J .A . (1973 ).

d S o lk a -F lo c BW -40 , Brown C o . , U SA .

e P rop ion ic ac id (0 .3 m l) can rep la c e potassium sórbate and n ipagin .

(1970).

T A B L E II. C U RREN T EST IM ATE D COST OF REARING O LIVE F R U IT F L Y PU PA E

Man-hours Cost in US $

Larva l d ie t - 29 .26

A du lt d ie t - 0 .08

Larva l d ie t preparation 4 .9 9 3 .3 4

A du lt d ie t 0 .06 0. 04

C ag in g , egg in g 24. 50 16.49

Other labour 8 .50 5 .70

M iscellaneous (approx. ) - 5 .09

T o ta l 38 .05 60. 00

Cost per 1000 pupae ($60/60 000 pupae) 1. 00

98 TS ITS IP IS

An o ve r 90% reduction in the cost o f rea r in g has been ach ieved with the introduced im provem ents, although it is understandable that a v e ry s tric t com parison of this cost with that estim ated by Tzanakakis et a l. (1968) cannot be made m ainly because o f the d ifferen t sca les of operation .

TO W ARD IM PRO V IN G THE PR E SE N T SYSTEM

Caging and egging

A s is m anifest from the production costs, m ost o f the labour (alm ost 65%) is devoted to maintaining the adult flie s and co llectin g the eggs. Hence, it was deem ed im pera tive to develop a m ore e ffic ien t system . P re lim in a ry resu lts with such a system showed that the rea r in g procedure could be g rea tly s im p lified . L a rge cages (1 m long X 0.3 m high X 0.4 m w ide) a re used to house the insects, and la rg e sem iperm anent ceresin -coa ted nylon gauze cones a re used as oviposition substrates. Four cones pass v e r t ic a lly through the cage, and the eggs that a re laid on the ir in te r io r walls a re rinsed with water and conducted by means o f a tubing system into a com m on recep tac le . Solid d iet is provided on cut-out trays on the P lex ig la s ce ilin g o f the cages. About 25 cm above the cages, 40 -Watt daylight fluorescen t light panels provide ample illum ination fo r even distribution o f the fl ie s in the cages (D r. L . F . S te in e r 's suggestion).

T o obtain eggs with high hatchability, the cones should be changed at w eek ly o r 10 -day in terva ls (this is eas ily done), and egg co llection should take p lace tw ice da ily . Only 2 - 3 m an-hours a re requ ired to se rv ic e 12 such cages g iv ing an approxim ate egg production o f o ver 150 000.F igu re 3 shows the tota l w eekly egg production at d ifferen t densities of flie s per cage com pared with that obtained from Hagen cages (about 1/3 as b ig as our new cages).

The h igher egg y ie ld and the m in im al labour requ ired suggest the adoption o f this system fo r m ass-rea r in g purposes, espec ia lly when an ti­cipated further im provem ents, and partia lly automated egg co llection , are introduced.

L a rv a l diets

Tab le I shows the com position o f two diets that appear prom ising fo r m ass rea r in g o f the o liv e fru it f ly . D iet PS (Manoukas, 1972) is v e ry s im ila r to diet T . Its textu re, depending on the amount o f ce llu lose (Solka- F lo c ), ranges between that of diets N and T fo r the low er and h igher amounts resp ec tiv e ly . The pupal y ie ld of the diet (Manoukas; unpublished resu lts ) amounted to between 2. 9 and 11.0 pupae/g o f diet with average pupal weights from 7.1 to 2.43 mg resp ec tiv e ly . At 5 pupae/g, the mean pupal weight was 5.45 m g, this being the low est weight of m ass-produced pupae from diets N and T . I f th is diet proves successfu l fo r rea rin g the insects fo r at least 2 -3 generations without any v igou r loss , its use fo r mass rea rin g would fu rther reduce the production cost because o f the low cost o f the ce llu lose (55 cents p er kg, or about 1/5 the cost o f the other ce llu lose used).

D iet L (M itt le r and T s its ip is , 1973) does not contain any inert m ateria l. The liquid diet is dispensed onto cotton tow elling on which the eggs are p laced. On a P e tr i-d ish sca le , y ie ld s o f up to 20 pupae/g o f d iet, with a

IA E A -P L -582/9 9 9

5x10'

5x10

5x10'

5x10‘

3 U WEEKS

FIG . 3. C u m u la tive w e e k ly eg g production o f Dacus o le a e m a in ta in ed at d iffe ren t popu lation densities in

la r g e (В, C , D , E) and Hagen (A ) cages. Each poin t is the m ean o f th ree rep lica tes ex cep t for cu rve E w here

each poin t represents on e r e p lic a te . Egg production is based on in it ia l number o f fem a les acco rd in g ly :

A = 90, В = 180, С = 370, D = 700 and E = 870.

5 m g mean pupal weight, w ere obtained. On a la rg e -tra y sca le , m icrob ia l contam ination occu rred . I f this prob lem is solved , developm ent o f a cheap la rv a l medium is anticipated.

Two recent tests with diet T supplied in rectangu lar p lastic trays (25 cm X 35 cm ) in la ye rs 2.2 cm thick (instead of the standard 30 -cm - d iam eter round ones in la ye rs 1.0 cm thick) gave pupal y ie ld s o f 5 and7.5 pupae/g o f diet w ith a respective average pupal weight o f between 5.5 and 6.5 m g. E viden tly , the diets a lready in use a re not optim ally u tilized , and resea rch toward that goa l is a requ irem ent.

H aving ra ised the e ffica cy o f the diet m anyfold, substitution o f certa in d ie tary components fo r cheaper ones now becom es appropriate ( e . g . Schwechat b re w e r 's yeast, kindly supplied by the IA E A entom ology group at S e ib ersdorf, was as good as the now ava ilab le F IX brand, although the fo rm e r is about 8 tim es cheaper).

Reduction o f production costs

S evera l steps in the rea rin g procedure could be s im p lified to low er the production costs: fo r exam ple, egg incubation, egg dispensation on the diet and co llection o f pupae. T o reduce the costs further, la rg e r la rva l diet m ix e rs and la rg e r rectangu lar trays fo r the la rva l diet could be used.

100 TS ITS IP IS

Future prospects

A s reported h ere , the production cost o f 1000 pupae with the present system is about 1 US $. I f the advocated im provem ents a re incorporated in this system , we w ill be able to reach the 1 m illion pupae per week le v e l, and the cost w ill hopefu lly drop su ffic ien tly to com pare favourably with the production costs o f other insects currently m ass produced, e . g . Anopheles albimanus (28 cents/1000 pupae) and sc rew -w orm (12.5 cents/1000 pupae), although we might not reach the m edfly cost o f 1 cent/1000 pupae in the near future.

A C K N O W L E D G E M E N T S

The author would lik e to express his appreciation to D rs . Economopoulos, Z e rva s , Haniotakis and Manoukas fo r th e ir useful d iscussions and to P ro f . Tzanakakis and D r. Manoukas fo r th e ir constructive c r it ic ism of the m anuscript. Suggestions by D rs . Gordon, Steiner, M itt le r and a ll FAO experts at "D em ocr ito s " a re gra te fu lly acknowledged.

R E F E R E N C E S

C A V A LLO R O , R . , G IROLAM1, V . (1968 ), N u ove techn ique d i a llevam en to in labora torio del Dacus o le a e

G m el. I . , A d u lt i. R ed ia j5 1 p 127.

ECONOM OPOULOS, A . P . , T Z A N A K A K IS , M .E . (1967 ), Egg y o lk and o l iv e ju ic e as supplements to the yeast

h yd ro lyza te-su crose d ie t for adults o f Dacus o le a e , L ife S c i. 6_p. 2409.

H AG EN , K . S . , S A N T A S , L. , TSECOURAS, A . (1963 ), "A techn iqu e o f cu lturing th e o l iv e f ly , Dacus o le a e

G m e l . , on syn thetic m ed ia under x en ic con d ition s", Radiation and Radioisotopes A p p lied to Insects o f

A g r icu ltu ra l Im portan ce (P roc . Sym p. Athens, 1963), IA E A , V ienna , p. 333.

M A N O U K A S , A . (1972 ), Research report on nutrition and chem istry o f th e o l iv e fru it f l y , Dacus o le a e ,

N u clea r Research C en ter "D e m o c r ito s " , A thens, G reece , D ocum ent N o . DEMO 72/9.

M ITTLE R , T . E . , TS IT S IP IS , J. A . (1973 ), E conom ica l rearing o f la rva e o f th e o l iv e fru it f ly , Dacus o le a e ,

on a liqu id d ie t o ffe red on cotton to w e llin g , Entom ol. Exp. A p p l. 16 p . 292.

O R PH AN ID IS , P. S . , PETS IKO U , N . A . , PA T S A K O S , P .G . (1970 ), E levage du Dacus o le a e (G m e l . ) sur

substrat a r t i f ic ie l , Ann. Inst. Phytop. B e n a k iN .S . j ) p . 147.

T Z A N A K A K IS , M .E . (1967 ), Con tro l o f th e o l iv e fru it f ly , Dacus o le a e (G m e lin ), w ith rad iation or ch em ica l

s te r iliza tio n procedures, N u clea r Research Cen ter "D em o c r ito s " , Athens, G reece.

T Z A N A K A K IS , M .E . (1971 ), Rearing m ethods for the o l iv e fru it f ly Dacus o le a e (G m e lin ), Ann. School

A g r ie . Forestry, U n iv . Thessa lon ik i 14 p. 293.

T Z A N A K A K IS , M .E . , ECONOM OPOULOS, A . P . , T S IT S IP IS , J .A . (1968 ), "A r t i f ic ia l rearin g o f the o l iv e

f ly : progress rep o rt" , Radiation , Radioisotopes and Rearing Methods in th e C on tro l o f Insect Pests (Proc.

Panel T e l A v iv , 1966), IA E A , V ienna p . 123.

T Z A N A K A K IS , M .E . (1970 ), Rearing and nutrition o f the o l iv e fruit f ly . I . Im proved la rva l d ie t and s im p le

containers, J. Econ. Entom ol. £ 3 p . 317.

IA E A -PL -582/10

COMPARATIVE BEHAVIOUR OF L A B .-C U LT U R E D A N D W IL D -T Y P E Dacus oleae FLIES IN THE FIELD

R.J. PROKOPY*, G.E. HANIOTAKIS,A. P. ECONOMOPOULOS

Nuclear Research Center "Democritos"Aghia Paraskevi,A ttik i, Greece

Abstract

COMPARATIVE BEHAVIOUR OF LAB.-CULTURED AND WILD-TYPE Dacus oleae FLIES IN THE FIELD.Under field conditions, the authors compared the responses of lab.-type (ca. 85 generations under artificial

conditions) and wild-type Dacus oleae flies to host plant colour and odour, host fruit colour and shape, small rectangles of different colours and shades, and McPhail-type traps of different colours baited with different odours. Except for the lab.-type flies being relatively more attracted toward red fruit models and small red rectangles and relatively less attracted toward yellow fruit models and small yellow rectangles than the wild type, the qualitative nature of the responses of the two fly types toward the various experimental treatments was essentially the same. Quantitatively,jhowever, consistently smaller percentages of the released lab.-type than the released wild-type flies were recaptured, suggesting that the mobility, flight pattern, or vigour of the two types of flies may be different.

INTRO D UCTIO N

As pointed out so w e ll by B o ile r [ 1 ], a key elem ent in the success or fa ilu re of the s te r ile - in sec t re lea se method approach to population m anage­ment is the behaviour of the re lea sed flie s . A s part of the current research program m e at "D em ocr ito s " j aim ed at evaluating the potential u tility of the s te r ile - in sec t re lea se method in an in tegrated approach to the suppression o f the o live fly , Dacus oleae (G m elin ), we in itiated a s e r ie s of studies com paring, under fie ld conditions, various behavioural responses of (a ) o live f l ie s cultured under a r t if ic a l conditions (ye llow wax domes fo r o v i­position, a r t if ic ia l m edia fo r¡th e la rva e ) fo r ca. 85 consecutive generations and re leased (= la b .-re lea sed f l ie s ), (b) o live f l ie s obtained from o lives , co llected in nature and re leased (= w ild -re lea sed f l ie s ), and in most cases (c ) o live f l ie s of the natural fie ld population (= w ild population fl ie s ). None o f the f l ie s in the studies sum m arized here was s te r ilized . The particu lar behavioural responses we investigated included responses to host plant (= o liv e ) colour and odour, hóst fru it colour and shape, sm all rectangles of d ifferen t colours and shades, and M cPha il-type traps of d ifferen t colours baited with d ifferen t odours. : Th is report is a b r ie f sum m ary of some of our findings to date. F o r a detailed account see R efs [2 -5 ].

* FAO-sponsored visiting scientist at "Democritos". Present address: The Farm, Rt. 1, Baileys Harbor, Wisconsin, USA.

101

1 0 2 PROKOPY e t al.

Our experim ents w ere conducted in o r adjacent to unsprayed o live g roves belonging to the C o llege of A gricu ltu re of Athens. They w ere located near the v illa g e of Spata, about 10 km from " D em o cr ito s ".

F rom tim e of ec los ion onward, the lab. - and w ild -re lea sed adults w ere maintained under the same laboratory conditions (both sexes together in cages provided with a continuous supply of protein , sugar and w ater but no oviposition medium ) and handled in the sam e manner (coo led fo r ca. 1 hour at 1 - 2°C fo r introduction into re lease containers). The ptilina of the flie s w ere m arked with Neon Red (la b .-re lea sed f l ie s ) o r A rc Y e llow (w ild - re leased f l ie s ) Day-G lo® fluorescen t powder. M arking was accom plished by placing the puparia under a thin la yer of a m ixture of 15% fluorescent powder and 85% ta lc sandwiched between two la yers of sand. A l l captured f l ie s w ere squashed between two p ieces of g lass and exam ined under u.v. light fo r the presence or absence of fluorescen t dye. As testim ony to the e ffec tiven ess of this m arking method, the dye was detected in the ptilina of 99.7% of ca. 2000 lab .- and w ild -re lea sed f l ie s held in the labora tory or in a la rge outdoor cage fo r up to 60 days. B o ile r and Remund, in co-operation with "D em ocr ito s " (unpublished data), have evidence from fligh t m ill studies that this particu lar m arking technique (with 30% fluorescen t powder in ta lc ) m ight have detrim enta l e ffec ts on the fligh t capab ilities of o live f l ie s so m arked. W hether this technique might a lso produce a lteration of the basic nature of some of the v isua l or o lfac tory p rocesses of the f lie s is unknown, but the fact that the nature of the responses of the w ild -re lea sed f l ie s con­fo rm ed so c lo se ly to the nature of the responses of the w ild-population f l ie s suggests that this was not an im portant factor in our studies.

No actual data are presented in this paper. Instead, we have assigned the value of 100% to the experim enta l treatm ent capturing the most f lie s (= f ir s t-p la c e treatm ent) and present the number captured in each of the other treatm ents as a percentage of the number captured in the firs t-p la ce treatm ent. W here the nature of the responses of the d ifferen t f ly types is described as being essen tia lly the same, the percentages g iven represen t an average value fo r the combined types.

GENERAL METHODOLOGY

R ESU LTS AND DISCUSSION

Responses to colour and odour of host plant

F o r the s te r ile - in sec t re lea se method to succeed, the re leased fl ie s must be able to locate the natural rendezvous site fo r mating. Except in the case of _D. cucurbitae Coquillet, the site of assem bly fo r mating in the tephritids thus fa r studied is p r im a rily , i f not exc lu s ive ly , confined to the host plant [ 6]. Although as yet we have not observed any actual matings of D. oleae in nature, we do have indications that mature f l ie s of both sexesassem ble in much la rg e r numbers on fru itin g o live tre e s than on non-fru iting o live tre e s o r tre e s of other species. We hypothesize, th ere fo re , that the p rincipa l mating site in D. oleae is probably fru iting o live trees . A ccord in g ly we assessed the f l ie s ' attraction toward o live tre e colour (o liv e tree fo liage vs. f ig tre e fo lia ge vs. painted surfaces vs. em pty space) as w e ll as toward o live tree odour (o liv e tree fru it vs. o live tre e fo lia ge and tw igs vs. em pty space).

IAE A -PL-582/10 1 0 3

F o r testing responses to colour, we em ployed tw o-d im ensional v e r t ic a lly erec ted m odels of trees . T o construct these m odels, we f ir s t built rectangu lar wooden fram es (200 cm wide X 130cm h igh , with l e g s l 3 0 cm long), stretched white nylon fish n et (10 mm X IO mm mesh,, each strand 0.3 mm thick) over each fram e, brushed the fish net with moulten B ird Tanglefoot® to capture a rr iv in g f lie s , and positioned the fram es in a row in an open ploughed fie ld .We then glued fresh -p icked o live o r f ig leaves onto 200-cm -w ide X 130-cm - high rectang les of c lea r P lex ig la s , or painted equ iva len t-s ize rectangles of plywood various colours, and placed these rectangles just behind the fish nets. We put containers of mature (14-19 days old) lab .- and w ild -re lea sed f l ie s under a dense canopy of fo lia ted o live branches, ca. 60 cm high, 3 m from each fram e. W ithin a few hours a fter each re lea se the f l ie s began to leave the canopy of o live fo liage , those fly in g toward the fo lia g e -co ve red or painted rectangles being in tercepted and captured by the fish net. The re lea ses w ere made under a canopy of host plant fo lia ge ra ther than into empty space to ensure as much as possib le that the f l ie s which le ft the re lea se site w ere not in an "escape m ood". The idea of using fish net to in tercept tephritid f l ie s in fligh t was f ir s t proposed by B o ile r [7] . Indeed, to the human eye the net proved n early in v is ib le and captured an average of 80% of the f l ie s which approacheji the rectangles.

We found that the naturé of the responses of the lab .-re lea sed f l ie s to the various experim enta l treatm ents was essen tia lly the same as that of the w ild -re lea sed f lie s . Both sexes of both types o f f l ie s w ere attracted in g rea test numbers toward |the bottom surface (100%) and top surface (83%) of f ig leaves and the top surface of o live leaves (95%), few er toward the bottom surface of o live leaves (60%) o r a combination of the top and bottom surface of o live leaves (59%), s t ill few er toward any of the painted surfaces (ye llow , black, red , blue, grlsy = 38 - 22%), and v e r y few toward aluminium fo i l o r empty space (6 - 7%)l Additional experim ents suggested that neither the odour nor pattern (tw o-d im ensional) of f ig o r o live leaves nor the odour of the painted surfaces had án im portant influence on the responses of e ither type o f fly . O f the 3500 f l ie s of each type re leased , 8.6% of the w ild-type and 7.5% of the lab .-type w ere recaptured on the nets.

Our conclusion is that mature f lie s of both the lab. - and w ild -types are adept at distinguishing re a l fo lia ge , apparently by its colour, from painted surfaces o r em pty space but that neither type is any m ore attracted toward o live tre e fo lia ge than toward the fo lia ge of a non-host tre e , fig .

F o r testing response to.odour, we patterned our approach a fter that of P rokopy et al. [ 8]. Thus, we placed the odour source in w ire screen con­ta iners covered with nylon tulle and hung these containers in sm all fru it le ss pear tre e s equipped with sm all s ticky-coated rectangles to capture a rr iv in g f l ie s o r attached the containers to the aforem entioned fram es of fish net in an open fie ld . Our re lea se procedure was the same as that fo r the co lou r-response study except that re lea ses w ere made sim ultaneously3 - 12 m up-wind and down-wind from the odour source.

F ies tas Ros de U rs in os ;et al. [9 ] have reported that o live f l ie s are p os itive ly attracted toward the odour of o lives . Unfortunately, we w ere unable to dem onstrate such attraction in our studies. Indeed, the le v e l of response of both sexes of both the w ild - and the lab .-type f l ie s (m ature, 10 days old) to washed or unwashed o liv e1 fru its (fre sh ly picked, m ixed susceptible va r ie t ie s in p rim e stage fo r oviposition ) was no d ifferen t from that to washed or unwashed o live leaves and tw igs (p icked from fru itin g and non-fru iting

104 PROKOPY et a l.

t r e e s ), a m ixture of o live fru its , leaves and tw igs, o r the controls ( = empty containers). O f the ca. 3000 f l ie s of each type re leased , 4.7% of the w ild - type and 3.9% o f the lab .-type w ere recaptured. W e cannot account fo r this lack of f ly response to o live fru it odour in our studies. The weather con­ditions appeared idea l fo r this type of study and there w ere no competing fru itin g o live tre e s within ca. 400 m of the pear tre e s or 150 m of the fram es. A lso , in this as w e ll as in a ll our other studies, the method of re lea se and the fact that the f l ie s w ere provided with an abundant supply of food righ t up until re lea se tim e should have ensured to a considerable degree that the f l ie s w ere not in an "escape or feed ing m ood" when re leased .Perhaps the concentration of odour emanating from the ca. 15 kg of o live fru it per treatm ent site was too weak to e lic it a positive response. Obviously, fu rther work, poss ib ly u tiliz in g a d ifferen t approach, is n ecessary before we can come to any conclusion about the com parative ab ility of lab .- and w ild -type o liv e f l ie s to detect the odour of o live fru it.

Responses to colour and shape o f host fru it

In addition to being the site of oviposition , the host fru it can, in some species of tephritids, also be a sp ec ific rendezvous site fo r mating [ 10].In an in itia l study we found that w ild-population o live f l ie s in o live tre e s flew just as frequen tly onto wooden m odels of o lives as onto re a l o lives . Th is finding indicated to us that once the f l ie s have a rr iv ed on an o live tree , they locate the fru it apparently so le ly on the basis of its physical characteris tics . We th ere fo re assessed the responses of w ild-population, w ild -re lea sed , and la b .-re lea sed f l ie s to o liv e -s iz e wooden m odels of d ifferen t shapes and colours. The m odels w ere coated with B ird Tangle foot to capture a rr iv in g f l ie s and w ere hung by w ire from the branches of la rge o live tre e s (fo r testing responses of w ild population f l ie s ) o r from the branches of a sm all o live tre e surrounded by a 2 .5 -m -d iam eter X 2 .5 -m -ta ll cy lin d rica l saran- screen cage (fo r testing responses of w ild -re lea sed and la b .-re lea sed flie s ).

We found that while the nature of the responses o f a ll three types of f l ie s to the various shapes of m odels was essen tia lly the sam e, the lab .- re lea sed type responded to certa in colours of m odels d iffe ren tly than the w ild -types. F o r the colour response test, a ll m odels w ere o live-shaped,31 mm ta ll and 20 mm in d iam eter at the centre. Mature fem a les of the two w ild -types w ere about equally attracted to ye llow (102%), b lack (100%) and red (98%) m odels and less attracted to green (83%), orange (77%), blue (49%), aluminium fo il (27%) and white (21%) m odels. H ow ever, mature fem a les of the lab .-type w ere re la t iv e ly m ore attracted to red (113%) than to black (100%) m odels and d istinctly less attracted to ye llow m odels (71%), with attraction to the other colours being essen tia lly the same as that of the w ild -types. Mature m ales of a ll three types of f l ie s w ere m ost attracted to ye llow , green and orange m odels, less attracted to black and red , and least attracted to blue, white and aluminium fo il. L ik e the fem a les , m ales of the lab .-type w ere re la t iv e ly m ore attracted to red and re la t iv e ly less attracted to ye llow com pared with w ild -type m ales. W ith respect to d ifferen t shapes of m odels (a ll having a surface area of 19.6 cm2 and painted b lack), mature fem ales of a ll three types w ere m ost attracted to o live-shaped and spherica l m odels (100 - 99%), less attracted to cubical m odels (42%), and least attracted to cy lin d rica l and rectangu lar m odels (21 - 20%). Mature m ales of a ll three types a lso w ere m ore attracted to o live-shaped and spherica l m odels than

IAE A -PL-582/10 1 0 5

to the others, though to a le s s e r degree than w ere the fem ales . O f the ca. 1500 f l ie s of each type re leased into the cage, 63.7% of the w ild-type and 53.1% of the lab .-type w ere recaptured.

Our conclusion is that fem ales of a ll three types of f l ie s are able to detect o live fru it on the basi's of its shape and colour (o r contrast against the background). The m ales ' responses w ere gen era lly s im ila r to those of the fem a les , but whether they represen t a response to the fru it as a ren d ez­vous site fo rm a tin g , a feed ing site, o r s im p ly a response to the movem ents of fem a les captured on the m odels is uncertain at this tim e. Both sexes of la b .-re lea sed f l ie s w ere com parative ly m ore attracted to red m odels and less attracted to ye llow m odels than the w ild -types.

Responses to sm a ll rectangles of d ifferen t colours and shades

F lie s of a number of te jih ritid species are known to be m ore attracted to sm all rectangles of ye llow colour than to equivalent rectangles of any other colour o r shade [ 11 - 13]. In some cases (e .g . Rhagoletis ce ra s i L . ), sm all sticky-coated ye llow rectangles hung in.host tre e s have proven v e ry e ffec tive devices not only fo r m onitoring f ly population density and m ovem ents but a lso in d irec t population suppression [14 ]. Hence, we com pared the responses of w ild-population, w ild -re lea sed , and lab .-re lea sed o live f l ie s to sm a ll (15 cm X 20 cm ), B ird -Tan g le foo t-coa ted rectangles of s ix d ifferent enam el colours o r shades. ¡The rectangles w ere hung from the branches of o live tre e s at m id -tree height, ca. 2 m apart and 50 - 100 cm from the outerm ost fo liage . The w ild - and lab .-re lea sed f l ie s (each type 3 - 7 days old) w ere re lea sed sim ultaneously ca. 1 m above ground at the trunk of each tre e harbouring rectangles. '

We found that the nature of the responses of the w ild -re lea sed f l ie s to the various colours and shades tested was essen tia lly the same as that of the w ild population f l ie s but d ifferen t from that of the lab .-re lea sed flie s .Both types of w ild f l ie s w ere most attracted toward the ye llow rectangles (100%), considerab ly less attracted toward the orange and green rectangles (56 - 50%), and not attracted toward the red, g rey and c lea r P lex ig la s rectangles (4 - 5%). On the jother hand, the la b .-re lea sed f l ie s w ere n early as attracted toward the orange and green rectangles (83 - 74%) as toward the ye llow (100%) and w ere i-e la tive ly m ore attracted toward the red (31%), g rey (12%) and c lea r P lex ig la s (8%) rectangles than w ere e ither of the w ild types. These colour response d iffe ren ces between the w ild and lab .-type f l ie s w ere true fo r both sexes. O f the 1800 f l ie s of each type re leased in this experim ent, 17.6% of the w ild -type and 12.1% of the lab .-type w ere recaptured. It is in terestin g to note that C era titis capitata (W iedemann) f lie s , which w ere a lso captured on the rectangles, p re fe rred ye llow (100%) to orange and green (26 - 27¡%) by a considerab ly g rea te r m argin than any of the three types of o live flie s . M ed flies w ere not attracted to the red , g rey o r c lea r P le x ig la s rectangle's (2 - 4%).

Our conclusion is that in com parison with rectang les of green and orange hues, ye llow rectangles are ¡more a ttractive to C. capitata f l ie s (as they are to R. pom onella and _R. ce ra s i f l ie s ) than to o live flie s . Lab .-type o live f l ie s proved in fe r io r to the w ild -types in hue d iscrim ination ability. Indeed, if g re y o r c lea r P le x ig la s could be considered as neutral surfaces and used as standards of com parison, then it is seen that the lab .-type w ere re la t iv e ly m ore attracted to red and re la t iv e ly less attracted to ye llow than the w ild

1 0 6 PROKOPY e t a l.

types. Owing to the apparent le s s e r capability of hue d iscrim ination in o live f l ie s (even w ild -type ) com pared with some other tephritid species, we postulate that odour-baited traps hold re la t iv e ly m ore prom ise than co lour- type traps as e ffec tive devices fo r detecting the presence of o live f l ie s in an orchard.

Responses to M cPha il-type traps of d ifferen t colours baited with d ifferen t odours

C lea r M cPha il-type traps baited with d ifferen t odours have been used ex tens ive ly to m onitor o live f ly populations in G reece. Coloured odour- baited M cPha il-type traps have also been evaluated fo r this purpose [15]. Hence, we com pared the responses of w ild-population, w ild -re lea sed , and la b .-re lea sed o live f l ie s to M cPhail-type traps o f two d ifferen t colours (c lea r vs. traps painted daylight fluorescen t ye llow , the most attractive colour we found fo r o live f l ie s ) baited with three d ifferen t odours (w ater vs. aqueous solution of 2% ammonium sulphate, the standard lure em ployed fo r detecting o live f l ie s in G reek o live g roves vs. aqueous solution of 2% Rodia-1.5% borax, the most a ttractive odour lure fo r o live f l ie s found in studies at "D em o c r ito s " ), with o r without a coating of B ird Tanglefoot (ВТ ) applied to the en tire e x te r io r of the trap. The traps w ere hung at m id -tree height in the southwest parts of o live trees , one trap per tre e in a ring of trees9 - 11 m from a cen tra l o live tree (without any traps), from which the w ild - and lab .-re lea sed f l ie s (each type mature, 8 - 1 5 days old) w ere re leased simultaneously.

W e found that the nature of the responses of both sexes of a ll three types of f ly to the various treatm ents was essen tia lly the same. A l l th ree types w ere captured in g rea test numbers by c lea r (100%) or ye llow (96%) traps baited with R od ia -borax and coated with ВТ. F ew er w ere captured by yellow , am m onium -sulphate-baited traps with В Т (62%) or c lea r , R od ia -borax- baited traps without В Т (55%). S till few er w ere captured by yellow , w ater-ba ited traps with В Т (45%) or c lea r , am m onium -sulphate-baited traps with ВТ (32%). The few est w ere captured by c lea r, am m onium -sulphate-baited traps without ВТ (10%) and c lea r, w ater-ba ited traps with В Т (1%). A lm ost a ll o live flie s captured by the traps coated with ВТ w ere entangled in the В Т, n early none being found in the in te r io r solution, indicating that o live f l ie s f ir s t land on the e x te r io r surface of a M cPha il-type trap b e fo re entering the in terio r.A lso , the fact that c lea r traps with В Т baited with R od ia-borax or ammonium sulphate captured m ore f l ie s than equivalent traps without ВТ indicates that many f l ie s which land on the M cPhail-type traps do not enter the in te r io r . Of the 2100 f l ie s of each type re leased in this experim ent, 34.6% of the w ild - type and 20.1% o f the lab .-type w ere recaptured.

Our conclusion is that a c lea r M cPha il-type trap baited with Rod ia-borax and coated with B ird Tanglefoot is an e ffe c tiv e device fo r m onitoring popu­lations of a ll th ree types of o live f ly studied. The addition of daylight flu orescen t ye llow , the m ost attractive colour yet found fo r o live f lie s , does not enhance the e ffec tiven ess of such a trap. But an odourless (i.e . w ater- baited) daylight flu orescen t ye llow trap coated with B ird Tangle foot is a m ore e ffe c tiv e trap than the standard c lea r am m onium -sulphate-baited trap, w ith o r without a coating of B ird Tanglefoot.

IAE A -PL-582/10 107

F o r m ost of the behavioural reactions assayed, the qualitative nature of the responses of the lab .rcu ltured o live f l ie s was essen tia lly the same as that o f the w ild -types. In certa in colour response assays, how ever, the lab .-type reacted d iffe ren tly from the w ild -types. Spec ifica lly , the lab .- type was re la t iv e ly m ore attracted toward red fru it m odels and sm all red rectangles and re la t iv e ly less attracted toward ye llow fru it m odels and sm all ye llow rectangles than the w ild types. W e have since detected an eye colour d ifferen ce between the w ild - and lab .-types and have reason to suspect a defic iency or im balance of nutrients o r conditions in the a r t if ic ia l la rva l diet as being the cause of the d ifference in eye colour and hue d is c r im i­nation ability.

On a quantitative basis,i the per cent recapture of lab .-cu ltu red re leased f l ie s was in e v e ry instance ¿m a ile r than the per cent recapture of w ild -type re leased flie s , supporting the e a r lie r indication from fligh t m ill studies (B o ile r and Remund in co-operation with "D em o cr ito s " , unpublished data) that the m ob ility fligh t pattern, o r v igour of the two types of f l ie s may be d ifferent.

A C K N O W L E D G E M E N T S

iWe wish to thank the C o llege o f A gricu ltu re of Athens fo r making their

o live g roves availab le to usj Drs. V. M oericke, E .F . B o ile r and G .L. Bush fo r supplying us with v ita l equipment and supplies, and the "D em ocr ito sMstaff, the FAO o live f ly group at Corfu, and Drs. G. Manikas and М. E. Tzanakakis fo r supplying us with o live f ly pupae. Th is study was made possib le through the support of UNDP/SF. G reece 69(525): "R esea rch on the control of o live pests and d iseases in Continental G reece , C rete , and Corfu” , and the G reek A tom ic E nergy Com m ission.

ii¡ R E F E R E N C E SiI

[ 1 ] BOLLER, E.F., B ehaviora l aspects o f m ass-rearing o f insects, Entomaphaga 17 (1972 ) 9.

[ 2 ] PRO KO PY, R.J., H A N IO T A K IS , G. È .,, Host d e tec tion by w ild and lab -cu ltu red o l iv e fru it flie s , Int.Sym p.

Insect-H ost Plant Relations, Hungary (1974).

[ 3 ] PRO KO PY, R.J., H A N IO T A K IS , G .Ë ., Responses o f w ild and lab -cu ltu red Dacus o le a e flie s to host plant

c o lo r , Ann. Entom ol. Soc. A m . (1974).

[ 4 ] PRO KO PY, R.J., ECONOM OPOULOS, A .P ., M cFAD D E N , M .W ., A ttraction o f w ild and lab -cu ltu red

Dacus o le a e flie s to sm all rectangles o f d iffe ren t hues, shades, and tints, Entom ol. Exp. A p p l. (1974).

[ 5 ] PRO KO PY, R.J., ECONOM OPOULOS, A .P ., A ttrac tion o f lab -cu ltu red and w ild Dacus o le a e flies to

s t ick y -coa ted M cP h a il traps o f d iffe ren t colors and odors, Environ. Entom ol. (1974).

[ 6 ] FLETCHER, B.S., ECONOM OPOULÓS, A .P . , Sexual b ehav io r in fru it f l ie s , in Report o f IBP B io log ica l

Control P ro jects , C am bridge. U n iv j Press (1974).

[ 7 ] CHAMBERS, D .L ., BOLLER, E .F ., FLETCHER, B.S., PRO KO PY, R.J., Idea book on fruit f ly m ovem ents,

Docum ent L o f IBP Fruit F ly W ork iiig Group (1973 ) 10 p.

[ 8 ] PRO KO PY, R.J., M OERICKE, V . , B¿JSH, G .L ., A ttrac tion o f app le m aggo t f lie s to odor o f apples, Environ.

Entom ol. 2 (1973 ) 743. >

[9 ] FIESTAS ROS de URSINOS, J .A . , C O N S T A N T E , E. G ., D U RAN , R .M ., RONCERO, A . V . , Etude d ’ un a ttra c tif

naturel pour Dacus o le a e , Ann. Entom ol. Soc. France 8 (1972) 179.

[1 0 ] PRO KO PY, R.J., B ENNETT, E .W ., BUSH, G .L ., M a tin g behav io r in Rhagoletis p om on e lla (D íp tera :

T ep h r it id a e ). I. S ite o f assem bly, Cañad. Entom ol. 103 (1971 ) 1405.

GENERAL CONCLUSIONS

108 PROKOPY e t a l.

[1 1 ] PRO KO PY, R.J., BOLLER, E .F ., Responses o f European cherry fruit flies to co lo red rectang les , J. Econ.

Entom ol. 64 (1971 ) 1444.

[1 2 ] PRO KO PY, R.J., Response o f apple m aggo t flies to rectangles o f d iffe ren t colors and shades, Environ.

Entom ol. 1 (1972 ) 720.

[ 13] M OERICKE, V . , A ttrac tion o f tephritid f lie s to co lo red rectan g les , in Report o f IBP B io lo g ica l Control

P ro jects , C am bridge U n iv. Press. (1974).

[1 4 ] RUSS, K . , BOLLER, E .F ., V A LLO , V . , H A ISC H , A . , SEZER, S ., D eve lopm en t and app lica tion o f visual

traps for m on ito rin g and con trol o f populations o f Rhagoletis cerasi L ., Entom ophaga 18 (1973 ) 103.

[1 5 ] O R PH AN ID IS , P .S ., Contribution a l'é tu d e du chrom ato-trop ism du Dacus o le a e (G m e l. ) , Experiences

en labora to ire e t en p le in a ir , Z . A n gew . Entomol. 74 (1973 ) 24.

PROGRESS REPORTS

Summaries of work done at various institutions

SUPPRESSION OF THE MEDITERRANEAN FRUIT FLY ORMEDFLY, Ceratitis capitata (WIEDEMANN), IN A SEMI-ISOLATED AREAIN CYPRUS BY THE USE OF THE STERILE-INSECT TECHNIQUE

C. Serghiou, J. W. Balock Agricultural Research Institute,Ministry of Agricultural and Natural Resources, Nicosia, Cyprus j

i

INTRO D U CTIO N

The M editerranean fru it fly , C era titis capitata (W iedemann), is a serious pest of c itrus, peaches, apricots, f ig s and other hosts in Cyprus. The lo sses due to m edfly attack and the cost of control a re currently estim ated at US $750 000 annually. Because of this and the geographic iso lation of Cyprus, erad ication of the m edfly from the island is considered.

In 1972, the fo llow ing p re lim in ary operations w ere ca rr ied out:(a) an is land-w ide trapping survey, and (b) test re lea ses of som e 28 m illion s te r ile m ed flies from August to O ctober. F rom these activ ities , data on w ild population s ize and dynamics, re lease lo g is tic s and s te r ile f ly d ispersa l w ere obtained. Th is in form ation was used in the 1973 fie ld experim ent described here. ¡

I

M A TE R IA LS AND METHODS

M ed flies w ere rea red in the insectary at 23 ± 2°C and under a 14-h photoperiod. They w ere kept in the usual organdy cy lin d rica l cages loaded with 50 000 - 60 000 pupae/ cage. The adult d iet was a 3 : 1 enzym atic yeast hydro lysa te : sugar m ixture with w ater separate. Eggs la id through the organdy dropped into pans of w ater placed beneath the cages. The cages w ere kept fo r 15 - 17 days and produced about 6 x 106 eggs/cage.

The pupae w ere produced in four room s containing each four racks of 50 la rva l rea r in g trays/rack i Each tray was loaded with 1. 5 kg o f medium consisting of bran, sugar, brlewer's yeast, nipagin, sodium benzoate and HC1 q. s. at pH4. A fte r 9 - 1 0 days, each tray y ie ld ed 17000-20000 pupae.

The pupae w ere irrad ia ted 24 - 48 h be fo re em ergence with 9 krad gamma rays. They w ere m arked by m ixing with a fluorescen t powder (T inopal SFG) at the rate of 1. 5 g/ litre pupae [ 1 ]. B e fo re this, D ay-G lo f ir e orange and D ay-G lo rocket red, tested accord ing to Holbrook et al. [ 2 ] , w ere d iscarded because they ¡in terfered with mating.

W ithin the Karpass peninsula (the NE land pro jection of Cyprus), the v illa g es of R h izokarpasso and Y ia loussa w ere se lected fo r the experim ent. Rh izokarpasso has an area of ca. 6 km2 in which a va r ie ty of m ed fly hosts a re grown m ainly in home gardens; sm all com m erc ia l citrus g roves (ja ffa oranges) a re a lso present. Y ia loussa, a v illa g e of s im ila r s ize and host distribution was used as control s ite . The two v illa g es a re separated by 18 km of fo res t, in which v e ry few m edfly hosts are grown.

Irrad ia ted pupae w ere transported by ca r from N icos ia to Rh izokarpasso (85 m iles ; 2 h/trip) 3 - 4 tim es a week. T o avoid overheating in transit, the pupae w ere packaged in 2 -m il p lastic bags at the rate of 2 l it r e of pupae/bag.

112 PROGRESS REPORTS

F IG . 1. M a le m ed fly ca tches in N a d e l traps baited w ith T r im ed lu re in 1972.

The bags, c losed with a rubber band, w ere packed in an insulated plastic picknick container together with a few fre e z e packs [ 3 ]. Upon a r r iv a l at Rh izokarpasso, the pupae w ere tran s ferred to paper bags (50 - 300 ml/bag) with a sm all amount of e x ce ls io r and kept 48 h in an a ir-cond itioned room at 23 - 27°C fo r em ergence.

S te r ile f ly re lea ses (in the late afternoon or ea r ly morning, depending on the tem perature) w ere started in ea r ly March to coincide with low w ild f ly population. F rom ea r ly M arch to 10 O ctober 1973, a total of 73 m illion f l ie s (based on pupal em ergence) w ere re leased . Th is was done by suspending on the trees the bags of em erged fl ie s and then splitting them open. T o ensure uniform distribution and m in im ize m ating between s te r ile fl ie s , the number of re lea se points was increased from 24 to 50 and fina lly to a few hundred, 50 - 100 m apart.

Sixty Nadel traps baited with 2 m l T rim ed lu re + 3% dibrom w ere d istributed equally between Rh izokarpasso and Y ia loussa to m onitor the w ild f ly population and the ra tio of s te r ile to w ild flie s . E ve ry week, the catches w ere exam ined under u. v. ligh t and, in doubtful cases, by S te iner 's technique [ 4 ] . Six additional traps w ere established concen trica lly some

PROGRESS REPORTS

Д.7

2 6 ' Л Х 2 5 \

ИЗ

MAR. APR. I MAY JUN. JUL. AUG. SEP. OCT.

F IG .2 . M a le m ed fly c itc h e s in N a d e l traps baited w ith T r im ed lu re in 1973.

2 km beyond the periphery of Rhizokarpasso. M ed fly su rv iva l at R h izokar­passo and at D eftera , a v illa g e near N icosia , was recorded during the re lea se program m e. F ru it co llected in Rh izokarpasso and Y ia loussa as it becam e ava ilab le was counted, weighed and held in cabinets to determ ine the number o f la rvae developing.

RESULTS AND CONCLUSIONS

F igu res 1 and 2 showing the w ild f ly catches in Rh izokarpasso and Y ia loussa fo r 1972 and 1972>, resp ec tive ly , illu stra te m edfly suppression in R h izokarpasso as a resuljt of the 1973 re lea ses . The Rh izokarpasso p eriph era l traps captured 45 marked and 17 w ild f l ie s during 1973.

A t D eftera , maximum su rv iva l was 57 days; however, as evidenced by trap catches, the half-lifje of the re leased f l ie s was no m ore than 1 week. S im ila r data w ere obtained at Rh izokarpasso. In 1972 and 1973, 1 week a fter suspension of re leases , trajl catches dropped to about one half and 2 weeksla te r to about one quarter, much m ore pronounced. Th host fo r 2 - 3 months would

F rom the th ird week onwards, the drop was ese data suggest that the absence of a susceptible be su ffic ien t to break the m edfly cyc le .

Data on la rva l in festation in sour and ja ffa oranges, apricots and figs a re presented in Tab le I. The m ost dram atic d ifferences in in festations

114 PROGRESS REPORTS

T A B L E I. C O M PA R A T IV E D A TA FOR IN F E S TA T IO N OF SOUR ORANGES, J A F F A ORANGES, APR IC O TS AND FIGS A T RH IZOKARPASSO AND Y IALOUSSA, 1973

Rhizokarpasso

No. of fruit (kg)

No. of larvae

perfruit

Infestation per

No. of fruit

Wt

(i<g)

No. of larvae

perfruit

per

Sour oranges

Jaffa oranges

Apricots

TABLE I. (Cont. )

11 5

Rhizokarpasso

No. of No. ofNo. of Wt No. ofper

j fruitper

Wtfruit (i<g) larvae fruit (kg) larvae

perfruit

Figs

18 Jul. 100 3.200 15 i 0.15 4.69 100 2.150 190 1.90 88.4

4 Aug. 200 6.900 4 1 0.02 0.58 200 6.000 482 2.41 80.3

11 340 12.350 40 i 0.12 3.24 296 7.650 122 0.41 15.9

18 324 9.500 2 ¡ 0.01 0.21 315 7.150 20 0.06 2.8

25 307 9.910- 8 ! 0.03 0.81 302 5.520 0 0 0

1 Sep. 300 5.905 2 i 0.01 0.34 280 6.430 24 0.09 3.7

8 291 5.610 4 1 0.01 0.71 300 5.575 32 0.11 5.7

15 300 5.020 7 0.02 1.40 300 6.180 308 1.03 49.8

22 300 4.310 7 0.02 1.62 300 6.105 1001 3.33 164

29 314 4.800 0 0.0 0.0 313 5.570 1010 3.23 181

6 Oct. 300 4.625 12 0.04 2.59 300 4.920 1619 5.40 329

13 342 5.660 8 0.02 1.41 300 6.285 854 2.85 136

20 300 6.100 3 0.01 0.49 300 6.250 1287 4.29 206

3718 83.890 112 ! 0.031

1.33 3606 75.785 6949 1.93 91.7

between the two v illa ges w ere obtained in figs in the fa ll and matched the d iffe ren ces obtained in com parative data fo r w ild f ly traps during the same period . j

During the re leases , in fe r t ile o r emjpty stings by irrad ia ted fem ales w ere observed in stone fruitsj during sum m er and in ja ffa oranges in ea rly O ctober, when these fru its begin to change colour. These stings should be taken into account but should not deter from im plem enting p rogram m es of s te r ile m ed fly re lea ses because of the la rge im m ediate and long-range benefits of such program m es,

R E F E R E N C E S

[ 1 ] SCHROEDER, W .J . , C U N N IN G H A M , R . T . , M IY A B A R A , R. Y . , FAR IAS , G .J . , A fluorescen t compound

for m arking teph ritid ae , J. Econ. E n iom ol. 65 (1972 ) 1217.

[23 HOLBROOK, F .R . , STEINER, L . F . , FU JIM O TO , M .S . , M a ting com petitiven ess o f M ed iterranean fru it

f l ie s marked w ith fluorescen t powders, J. Econ. Entom ol. 63 (1970 ) 454.

[ 3 ] T A N A K A , N . , Personal com m u n ica tion .

[4 ] STEINER, L . F . , A rapid m ethod for id en tify in g d ye-m arked fru it f l ie s , J. Econ. Entom ol. 58 (1965 ) 374.

116 PROGRESS REPORTS

STATUS AND PROSPECTS OF MEDITERRANEAN FRUIT FLY CONTROL BY THE STERILE-INSECT TECHNIQUE IN PERU

J. E. Simón FDirección General de Investigaciones Agropecuarias,Ministerio de Agricultura,Lima, Peru

In Peru , m ass rea red and s te r iliz ed m ed flies w ere re leased during 1972 and 197 3 as part of an integrated control program m e. The re lease site was the Moquegua va lley which contains various fru it-b earin g hosts.It starts at 2 800 m in the Andes and extends to the west down to the sea fo r about 80 km. The v a lle y is iso lated north and south by barren h ills and a 40 - 50 km desert. F rom sea le v e l to the east, the experim enta l area was d ivided accord ing to treatm ents into three successive zones: (1) a40-km -long control zone where trapping only was ca rr ied out, (2) a 20- to 25-km -long re lea se zone with some insectic ide spraying and (3) the in sec ­tic ide zone.

F lie s w ere produced and s te r iliz ed with 9 krad gamma rays at La Molina,1 200 km north of Moquegua, in p rovis iona l fa c ilit ie s , a llow ing fo r a m axi­mum production of 40 m illion flies/w eek . H ow ever, a unique "m ed fly fa c to ry " is being completed. Its fa c ilit ie s provide: (1) a 15 hp steam b o ile r fo r d is ­in fecting equipment and supplies, (2) a laundry, (3) a m onorail system fo r transporting cages etc ., and (4) a c lo se -c ircu it te lev is ion system to enable the superintendent to control 80 w orkers. W arehouse space in the basement w ill stock 6 months' supplies. The fa c to ry includes a 1 600 m3 a ir-conditioned adult room ; a 1 300 m3 la rva l jumping room ; a 300 m3 pupation room ; two pupae holding room sbof 200 m3 each; space fo r quality control, o ffices and a ca feteria . The production w ill reach 250 m illion flies/w eek .

W ithin the th ree zones, 275 Steiner traps baited with T rim ed lu re w ere setup. Between O ctober 1972 and September 197 3, the w ild population reached its peak in the control zone in Decem ber, whereas in the other two zones it went through a maximum in May. In addition to trapping, in festation was fo llow ed by fru it sam pling in the three zones.

Until July, the cumulative number of chem ical treatm ents per tree was g rea te r in the re lea se zone (6.45) than in the insectic ide zone (6.30); however, by September, the total fo r the re lease zone (6.74) was le ss than fo r the insectic ide zone (7.46). In the re lease zone, some 530.5 m illion s te r ile f l ie s w ere re leased with a monthly average of 44.2 (range: 10.0 - 69.6).

The resu lts w ere not c lear-cu t, e.g. in festation of guavas (a favourite host of the m ed fly ) harvested in A p r il to September was 18% in the control zone and 19 - 74% in the re lea se zone, but m andarines harvested from May to August w ere 20% in fested in the control zone and in fes ta tion -free in the re lea se zone where the population peak is in May. The period of this report was fraught with techn ical d ifficu lties . These are being solved and the tr ia ls w ill be repeated with the la rg e r m edfly fa c ility in operation.

PROGRESS REPORTS 1 1 7

STATUS AND PROSPECTS OF MEDITERRANEAN FRUIT FLY CONTROL INVESTIGATIONS BY THE STERILE-INSECT TECHNIQUE IN ARGENTINIA

A. TuricaInstituto Nacional de Tecnología Agropecuaria,

C I C A , !Castelar, Buenos Aires,Argentina

The annual fru it production o f A rgentina is some 4.2 m illion tons of which 2.5 are grapes, 0.2 stone fru its and 1.5 citrus fru its . O f this total annual production, 10 - 20% Are damaged by the m ed fly and only 2% by the South Am erican fru it f ly (Anástrepha fra te rcu lu s ). An eco log ica l study ca rr ied out in northern A rgentina showed that A. fra tercu lus is active during the ra iny season (N ovem ber-M arch ) whereas the m ed fly is active during 9 months (O ctober-June). Hence, the much g rea te r im portance of the m ed fly as a citrus pest.

Between 1966 and 197 3, three fie ld experim ents w ere ca rr ied out to test the fe a s ib ility of the s te r ile - in sec t technique fo r m ed fly control.

The f ir s t two experim ents took place in the Concordia province (just north o f Buenos A ire s ). In l|967, a 30-ha citrus area with a h istory of 40% in festation in grapefru its was the re lea se site. A screen of T rim ed lu re traps at a density of 7/ha was insta lled to decrease the in itia l w ild male population. Subsequently, 1.275 m illion m ed flies s te r iliz ed with 10 krad w ere re leased during F eb ru ary to May. F rom March to July, the trapped population dwindled to ze ro . During the fo llow in g 3 yea rs no fu rther m ed flies w ere trapped in the area, nor was there any fru it infestation.

The second experim ent took place between 1968 and 1969 in a 2 700-ha sem i-iso la ted com m erc ia l citrus area a lso containing some peaches and figs . Bait sprays preceded the re lea ses of s te r ile m ed flies during the sum m er o f 19R8. A tota l of 5 m illion such f l ie s w ere re leased on a w eekly schedule. The number of trapped m ed flies decreased and by A p r il 1969 only 25 w ere caught in the re lea se area. As opposed to this, in the chem i­ca lly trea ted control area, the catch was then 110 - 116 flie s . G rapefru it in festation in the re lea se area was 0.4% com pared with 15% in the control area.

The th ird experim ent was in itiated during 197 3 in a 60-ha iso la ted citrus area in the north -w estern part of the country (between Chile and B o liv ia ). The e ffec t of trap ¡density on m ale catch was studied: in 3 months, 2.0 T rim ed lu re traps/ha caught 202 m ed flies whereas with 0.15 traps/ha the catch fo r the same period was nil. The m ed fly population was thus f ir s t reduced by bait sprays and T rim ed lu re traps at a density of 2.0/ha. The resu lts of subsequent re lea ses of s te r ile m ed flies w ill be evaluated by fru it sam pling, trap catchesjof liv e fem a les and tests of the ir fe r t i l ity in the laboratory.

In addition, two sm all fie ld tests w ere made in the Buenos A ire s province in a 2-ha orchard óf m ixed species. The f l ie s re leased w ere irrad ia ted in the late pupal stage with, resp ec tive ly , 7 krad and 9 krad gamma rays. They w ere g iven a protein hydrolysate diet to increase their

1 18 PROGRESS REPORTS

surviva l. On an average, 3.5 m illion irrad ia ted f l ie s w ere re leased during4 months and the area rece ived no other treatm ent. A t harvest, the mean in festation of citrus fru it in the re lease area was 1% com pared with 18% in the untreated control area. There was some sting damage to grapefru it in the re lea se area.

STUDIES ON THE CONTROL OF THE MEDITERRANEAN FRUIT FLY,Ceratitis capitata (WIEDEMANN), USING GAMMA RADIATION

A .M . WakidAtom ic Energy Establishment,Cairo

A . ShoukryNational Research Centre,Dokki, Cairo, Egypt

The research described had two ob jectives: (a) to im prove the la rva l diet used h itherto in Egypt fo r rea rin g the m edfly and (b) to test the com petitive ­ness of irrad ia ted m ales re leased in fie ld cages together with s im ila r ly treated fem ales and norm al individuals of both sexes.

In im proving the la rva l rea r in g medium, the aim was to d ecrease the cost of lab o ra to ry -sca le production. This was done by rep lacing dehydrated ca rro t powder by wheat bran. The com position of the la rva l d iet used was (in g or ml, resp ec tiv e ly ): wheat bran 1 000; b rew er 's yeast 250; sucrose 250; HC l (2N) 15; sodium benzoate 15; w ater 2 000. The cost of1 000 pupae produced on this medium is 0. 02 E£ com pared with 0. 04 E£ with the ca rro t medium; a lso , the mean pupal weight increased from 8. 0 mg to 9. 8 mg. Adults produced w ere kept in the usual cy lin d rica l hanging cages made o f synthetic cloth with p lastic dishes at either end. F lie s w ere fed a m ixture o f yeast hydrolysate: sugar (1:3 parts ) put in a P e tr i dish on the bottom o f the cage. Drinking water was o ffe red in a g lass ja r hanging from the roo f o f the cage. Eggs la id through the cloth fe l l into w ater within a tra y of w id er d iam eter than the cage and put below it. Six fie ld cages w ere used in the com petitiveness tests . They com prised two groups of three adjoin ing cages separated by a s e rv ic e co rr id o r ; the outward facing aspects w ere of w ire screen , the other partitions g lass. Each cage measured 3 m x 3 m x 2 . 5 m . A Casuarina equ isetifo lia tre e within the cages was used fo r hanging th ree oviposition dev ices . These w ere p lastic m andarines half f i l le d with w ater with the upper half fin e ly perforated . Food and water fo r the adults w ere provided.

The test f l ie s had a ll been reared on the medium described . Pupae and adults w ere kept at 2 5 ± 2°C; the pupae w ere irrad ia ted 1 day before em ergence in a gam m acell d e live r in g 45 rad/s. In the tests, known volum es o f pupae w ere used from which sam ples w ere taken to determ ine % em ergence. In this manner, the number of f l ie s re leased and the ra tios of irrad ia ted -to -n o rm a l flie s could be estim ated. A control cage of 30 m l

PROGRESS REPORTS 119

T A B L E I. EGG H ATCH O B TA IN ED WHEN M A LE AND F E M A LE C era titis capitata IR R A D IA TE D (I) ONE D AY BEFO RE EM ERGENCE W ERE COMBINED W ITH U N TR E ATE D (N) M ALES AND FE M A LE S IN VARIOUS RATIO S, TO G ETH ER W ITH TH E E X PE C TE D EGG H ATCH AND M A LE C O M PE TIT IVE N E SS V A LU E S

D ose

(k rad )

T es t ra tio o f : A v g . °}o

observed

eg g hatch

A v g . °¡o

expected

eg g hatch

A v g .

com petitiven ess

va lu e

A v g . w eek ly

com petitiveness

va lu e

I d" : I ? : Nd* : N ?1st

w eek

2nd

w eek

3rd

w eek

5 0 : 1 1 : 1 94 .3 - - -

1 : 0 : 0 : 1 5 ; 4 - - -

2 .1 : 2 .1 : 1 : 1 80 ,2 34 .08 0 .089 0 .20 0 .07 0

12 .9 : 1 2 .9 : 1 : 1 50 .3 11 .79 0.076 0 .15 0 .07 0

7 0 : 0 : 1 : 1i

92!. 9 - - -

1 : 0 : 0 : 1 2 .3 - - - -

1 .8 : 1 .8 : 1 : 1 8 2 .1 34 .66 0.075 0.18 0.04 0

13 .5 : 13 .5 : 1 : 1 5 J . I 8 .55 0.067 0 .12 0 .08 0

9 0 : 0 : 1 : 1 90 .2 - - - -

1 : 0 : 0 : 1 1 .1 - - - - -

1 .9 : 1 .9 : 1 : 1 80 .6 31 .82 0.063 0.15 0 .05 0

12 .6 : 12 .6 : 1 : 1 51 .21

7 .65 0 .062 0 .14 0 .07 0

norm al pupae served fo r testing the fe r t i l it y of untreated m ales. The s te r il ity o f the treated m ales was assessed in the laboratory by confining2 5 irrad ia ted m ales with 25 norm al fem ales and testing egg hatch during3 weeks.

About 1 500 adults/cage w ere used and egg sam ples w ere taken fo r incubation 5 tim es/w eek until the fem ales died or stopped ovipositing. Com petitiveness of the m ales re leased was assessed by using F r ie d 's p a ra m e te r1. R esu lts a re shown in Tab le I.

D oses o f 5 - 9 krad led to a lm ost s im ila r reduction in egg hatch but com petitiveness decreased ¡with increas ing dose. A t a ll doses tested, the com petitiveness o f the m ales was le s s at 13 : 1 3 : 1 : 1 ra tio then at 2 : 2 : 1 : 1 ra tio . H ow ever, there was no c lea r indication of whether m ale com petitive ­ness at a particu lar dose wks a ffected by the ra tio of irrad ia ted m ales to untreated m ales and fem a les .

A t both ra tios , 5 -k rad jtrea ted m ales gave the best com petitiveness values. The values w ere h igher than those obtained with m ales treated with7 or 9 krad. The 9 -krad-trea ted m ales gave the poorest control. Th is may be attributed to the adverse e ffe c t of that dose on m ale com petitiveness.

I

D e te rm in a tion o f s te r ile insect com petitiven ess . J. Econ. E n to m o l., 6 4 (1 9 7 1 ) 869.

120 PROGRESS REPORTS

G enera lly , the com petitiveness of m ales decreased in successive weeks, but the ra te of decline was g rea te r at the 2 : 2 : 1 : 1 ra tio than at the 1 3 : 1 3 : 1 : 1 ra tio . In the th ird week, egg hatch was as high as the controls (norm al m ales with norm al fem a les ). Th is may be attributed to the short l i fe of the treated m ales.

RAISING AND MULTIPLYING OF THE EUROPEAN CHERRY FRUIT FLY, Rhagoletis cerasi L.

A . HaischBavarian State Institute for Soil and Plant Cultivation, Munich, Federal Republic of Germany

A va ila b ility o f la rge numbers of ch e rry fru it f l ie s is a p rerequ is ite fo r con tro lling this pest by the s te r ile - in sec t technique. T h ere fo re , considerab le e ffo rts w ere spent in developing and im prov ing an a r t if ic ia l la rva l d iet g iv ing high y ie ld s of pupae in the shortest possib le tim e.Another p rob lem was to determ ine the conditions fo r shortening the post­diapause developm ent of the pupae. The fo llow ing is a sum m ary of the work ca rr ied out to fu lf i l l these ob jectives.

The a r t if ic ia l la rv a l d iet developed contained (in g o r m l, resp ec tive ly ): Toru la yeast 5. 6; wheat germ 4. 0; sucrose 4. 0; Vanderzant's vitam in m ixture 1.0; a ga r-a ga r 4 .2 ; propionic acid 0 .4 ; HC1(4N) 0.4; w ater 80.4.The fina l pH of this medium was 4. 0. Th is la rv a l d iet, dispensed in P e tr i dishes, was used as a standard fo r the nutrition experim ents. F irs t- in s ta r la rvae , gathered 3 tim es a day from eggs co llected daily and incubated, w ere seeded individually on this diet. Under these conditions, pupation occurred within 9 - 1 4 days, pupal y ie ld was 46% with a mean pupal weight o f 3. 9 mg and the medium rem ained fr e e from o ve rt m icrob ia l contamination. H ow ever, when eggs w ere co llected at longer in terva ls and f ir s t instars tran s fe rred in groups o f 20 - 50, la rva l developm ent took 3 - 4 weeks, pupal y ie ld dropped to 10%, pupal weight to less than 3 m g and 50% of the pupae died a fte r 3 - 5 weeks. These e ffects a re ascribed to bacteria l contamination favoured by le s s frequent co llections of eggs and neonates.

T o ru la - and b rew e r 's yeast w ere com pared as la rva l nutrients. Th ere was a highly sign ifican t d iffe ren ce in pupal m orta lity : 50% with toru la yeast and 15 - 34% with b rew e r 's yeast. T oru la im parted a "g re a s y " consistency to the medium.

When the amount of wheat germ in the diet was va r ied (0 - 3. 6% by weight),, the optimum concentration fo r pupal weight and y ie ld was 3%. T o determ ine the nutritive ro le o f wheat germ , this ingred ient was su ccess ive ly extracted with s ix solvents o f in creas ing po larity . The success ive extracts, the residues and the ir corresponding combinations w ere added to the standard d iet in rep lacem ent o f 4% (by weight) wheat germ . No pupation was obtained with any o f the extracts; however, a ll the residues and success ive com bina­tions of residue and extract resu lted in pupal production. Only with the last two solvents in the s e r ie s (methanol and methanol and w ater), which extract

PROGRESS REPORTS 121

protein , was there a sign ifican t drop in percentage pupal y ie ld . The evidence suggests that wheat germ has m ore of a textura l then a nutritive function and thus s tresses the im portance o f the physical condition of the diet.

The e ffec ts of storing pupae fo r d ifferen t periods of tim e and at d iffe ren t tem peratu res on the duration o f pupal diapause w ere studied. Batches of pupae from the F ed e ra l Republic of Germ any and Hungary w ere kept each at 0°, 2°, 4° and 6°C fo r 120, 140 and 180 days. The param eters m easured w ere: (a) the % em ergence, (b) the em ergence period , and (c) the meanpost-d iapause developm ent period in days. (PDD, i. e. tim e elapsed between end of storage and mean period of pupal em ergence. )

The a llopa tric pupal populations d iffe red most in the ir PDD: low tem pera ­tures o r a short storage period prolonged the developm ent of Hungarian m ore than Germ an pupae.

Between 4° and 6°C, diapause m etabolism was observed to proceed fastest. T h e re fo re , in p ractice , pupae should be stored at these tem pera­tures fo r 120 - 140 days to avoid a drop in % em ergence or a prolongation o f the PDD. '

PERFORMANCE OF NORMAL AND GAM M A-RAY STERILIZED LABORATORY-REARED Dacus oleae FLIES IN THE FIELD.AN ATTEM PT TO SUPPRESS 'THE NATIVE POPULATION IN A SEMI-ISOLATED AREA BY THE STERILE-INSECT TECHNIQUE

A .P . Economopoulos, G. Haniotakis, N . Avtzis, J. Tsitsipis, G. Zervas, A. ManoukasNuclear Research Center "Democritos” ,Aghia Paraskevi, Attik i, Greece

In G reece, the o live fly; Dacus oleae is the m ost serious pest of the o livefru it. R esearch is being conducted at the D em ocritos N uclear R esearchC enter with the ob jective o f developing con tro l o f the o liv e f ly by the s te r ile -insect technique as one o f s e ve ra l in tegrated s tra teg ies . F rom June 1971 toN ovem ber 1973, a s e r ie s o f fie ld tests w ere ca rr ied out which la id the basis

’ ifo r and culm inated into a tr ia l of o live fly suppression by the s te r ile - in sec t technique. Both these tests and the control experim ent took p lace in a s em i­iso la ted o live g rove in northern G reece (Kassandra, Halkidiki Peninsula); they a re sum m arized belowi.

The f ir s t s e r ie s of re lease/recap tu re tests (June 1971 - July 1972) dealt with point re lea ses o f sm a ll numbers (maximum 3 500) of o live flie s a r t if ic ia lly rea red and s te r iliz ed in thé pupal stage. The re lea ses took p lace at the end o f the spring, beginning and end of sum m er, ea rly and la te fa ll and m id ­w in ter. Trapp ing resu lts revea led a tendency of the w ild flie s to concentrate at the re leased site. By the beginning of June v e ry few w ild fem ales had mated or w ere gravid whereas at the beginning of the fa ll, the m a jority contained sperm atozoa and imature eggs. By the end of the fa ll, insem ination and grav id ity declined and reached a m inimum in w inter. W inter captures

122 PROGRESS REPORTS

took p lace on w arm sunny days which indicates that, in northern G reece , the o liv e f ly can overw in ter as an adult. In general, re leased fl ie s w ere recove red m ainly during the fo llow ing 2 weeks.

In the second re lease/recap tu re test se r ie s (M arch 1972 - A p r il 1973), la rg e numbers of adults (maximum 41 092) w ere used. Six single-poin t re lea ses w ere made with both s te r iliz ed and norm al f lie s (five in spring, sum m er, fa ll, one in w inter) and one 4-point re lease with s te r iliz ed flie s only (w in ter). A l l f l ie s w ere rea red on an a r t if ic ia l d iet except fo r the norm al f l ie s used in the w inter single-po in t re lease : these w ere rea red in o lives .

A l l s te r ile f l ie s w ere irrad ia ted in the pupal stage, 1 - 2 days before em ergence. The pupae w ere transported by car on the day of irrad ia tion and kept below 28 - 30°C. They w ere put in trays and covered by successive la yers of (a) sand (1 mm thick); (b) 30% fluorescen t dye in talc ( 1 - 2 mm) and (c) sand (8 - 10 m m ). These trays w ere placed in em ergence cages containing adult food. S te r ilized and norm al f l ie s w ere re leased from the cages sim ultaneously and the food was then rem oved. The trapping screen was not baited during 1 - 5 days fo llow ing re lea se to assure fr e e d ispersal. T h erea fte r the traps w ere baited with 3% aq. "R hod ia" protein (p reserva tion la te r im proved by adding 1. 5% borax). Again w ild f lie s w ere strongly attracted to the re lease site possib ly because of a high concentration of pherom one(s). In O ctober - N ovem ber, the decline in insem ination and grav id ity among w ild fem ales was again observed . M ost of the re leased flie s w ere found less than 60 m from the re lea se points and, th ere fo re , in a control operation these should not be m ore than 100 - 120 m apart. L ikew ise , since the ra tio of re leased/w ild flie s within 60 m of the re lea se point rem ained high only during 8 - 1 0 days, w eekly re lea ses would be requ ired .

In the w in ter s ingle-po in t re leases of norm al f l ie s rea red on o lives and s te r iliz ed f l ie s rea red a r t ific ia lly , the saliant resu lt was the reco ve ry of a norm al fly 4 months a fte r re lease , again con firm ing the poss ib ility of adults overw in tering in northern G reece.

A s a last p re lim in a ry to the control experim ent, a r t if ic ia lly reared f l ie s w ere irrad ia ted as adults and not pupae. B efore their re lease , they w ere kept in bags fo r 24 h e ither active o r im m ob ilized by cooling. Sucrose was provided . The main advantages of this procedure w ere found to be ve ry low m orta lity , good d ispersa l and up to 40% recove ry .

The preced ing in form ation was used in the control experim ent ca rried out during M ay - N ovem ber 1973. Starting during the la tte r part of May,800 trees w ere sprayed with Lebaycid , fo llow ed in m id-June by D im ecron with "C era ten e " protein . Tw o weeks a fter the second treatm ent, weekly re lea ses w ere started and continued until N ovem ber 1973. Each of these consisted of 100 000 - 150 000 adults of both sexes treated with 9. 5 krad gamma rays when 1 - 4 days old. The adults w ere handled as in the last test and transported by night. They w ere re leased in the m orning from points less than 60 m apart. Each week, o lives w ere examined fo r infestation and liv e trapped f l ie s fo r s te r ility . Trapping and fru it in festation records from two untreated g roves , resp ec tiv e ly 2. 7 km and 3. 3 km distant from the re lea se grove, provided com parative data. By October - Novem ber, the o ve ra ll in festation in the re lea se grove was 3 tim es low er than in the control groves . H ow ever, in the re lease area fungus in festation of the fru it was 3 tim es h igher than in the control g roves ; this is probably due to stinging by re leased fem a les .

PROGRESS REPORTS 1 2 3

RELEASE OF STERILE AND MARKED OLIVE FLIES ON THE ISLET OF SIT (KORNÀT ARCHIPELAGO)

D. BrneticInstitute for Adriatic Agriculture and Karst Reclamation,Split, Yugoslavia

In Yugoslavia , some 5 m illion o live tre e s are d istributed alm ost along the en tire coasta l te r r ito ry including the islands. During the past 10 yea rs , in terest in this crop has re v iv ed because of the canning industry. The o live f ly , Dacus oleae (G m elin ), destroys about 35% of the o lives annually. Control of this pest is c a rr ied out with organ ic phosphorus in sectic id es which cause residue prob lem s and, m ore im portantly, a calam itous upsurge of the sca le Saissetia oleae. T h ere fo re , an e ffo r t is at present being made to develop b io lo g ica l control of the o live fly , including the s te r ile - in sec t technique. In the fie ld , this e ffo r t centres on an eco log ica l study of the o live f ly ca rr ied out on some is le ts within the Kornat A rch ipe lago located o ff Split along a SE-NW direction . These rocky islands are uninhabited; on them, som e pockets of arable so il with 50 to a few hundred o live tre e s fo rm oases cu ltivated by owners liv in g on the continent. The clim ate is m ild with mean tem peratu res increasing from 7.1°C in January to 24.1°C in August and down again to 8.6°C in Decem ber. The average RH is 65% and snow is v e ry ra re . i

M cPha il traps baited with 2% aq. ammonium bicarbonate w ere established on the Kornat islands Sit and Scitna, screened from the mainland by Pasm an island on which traps w ere ¡also located. In addition, traps w ere put on the island of Gangaro windward and o ff the southern tip of Pasman.

The traps w ere s e rv ic ed in conjunction with the re lea ses of co lou r- m arked and s te r iliz ed f l ie s re c e iv ed from Seibersdorf. W ild fem ales caught w ere d issected to assess gravid ity . Samples o f o liv es w ere exam ined p e r io ­d ica lly to fo llow natural infestation.

During 1972 and 197 3, w ild f l ie s w ere trapped in w inter as w e ll as in the warm season, the population reaching a maximum in September. V e ry few w ild fem ales trapped in June contained mature eggs. H ow ever, g rav id ity rose stead ily during July and the beginning of August, subsided during the la tter part of August to the beginning o f Septem ber, reached the season 's peak in September and decreased th erea fter. F ru it in festation re flec ted this trend : in September toj O ctober in festation reached and exceeded 100%, i.e .1 there was m ore than one individual in a single fru it. The same trend was observed in 197 3 when in festation again began to r is e at the beginning of autumn.

During M ay — Octobeij- 197 3,an average of 3 343 fl ie s w ere re leased on a b i-w eek ly schedule. Th is was done from a single point on Sit where m arked f l ie s w ere recaptured by the furthest trap, i.e . 1 km away from the re lea se site. H ow ever, m arked fl ie s w ere a lso reco ve red as fa r as Pasm an, i.e . 4.5 - 5.0 km downwind. Th ere is litt le doubt that this d isp ersa l was due to the wind because, apart from the traps on Sit and Pasm an, none of those on Scitna and Gangaro (re sp ec tiv e ly 3.0 and 12.0 km from the re lea se point) caught any m arked flie s .

Th is work w ill be repeated with la rg e r re leases .

124 PROGRESS REPORTS

CONTROL OF FRUIT FLIES BY THE STERILE-INSECT TECHNIQUE.STUDIES ON STERILIZATION, POPULATION DYNAMICS, FRUIT INFESTATION SEQUENCE AND DISPERSAL OF Dacus dorsalis HENDEL

R. S. RejesusUniversity o f the Philippines at Los Baños,Laguna, Philippines

In the Ph ilipp ines, exportation of mango, w ater-m elon , cantaloupe, etc., is lim ited by the orien ta l fru it f ly , Dacus dorsa lis Hendel. Control of this pest is envisaged as a combination of the s te r ile - in sec t technique, m ale annihilation, bait spraying and post-harvest com m odity treatm ents. The various studies requ ired fo r the im plem entation of th is program m e are d ivided among three national institutions: the A tom ic E nergy Com m ission, the Bureau of P lant Industry and the U n ivers ity of the Ph ilippines at Los Baños.

The b io logy of the orien ta l fru it f ly was studied on banana, mango, papaya and guava: there was no sign ificant d ifference in the duration of the developm ental stages. A t 80 to 85°F the tota l life cyc le took 19.28 days, p re-ov ipos ition lasted an average of 8 days and adult longevity extended from 20 to 25 days.

The f ly p re fe rs fu lly ripe fru its fo r oviposition but can also use less mature hosts. A l l 54 host species tested supported development up to the pupal stage, but there w ere d ifferences in la rva l developm ent, s ize and m orta lity .

F o r mass rea rin g , a la rva l medium based on lo ca lly availab le nutrients was developed containing in gram s: cooked ye llow sweet potato 50; r ic e bran 100; a lo ca l brand of b rew e r 's yeast (SM C) 33; sugar 10; Na benzoate 1.5; w ater 250; H C l q.s. at pH 4.5. The incorporation of yeast shortened la rva l developm ent to 6.5 - 7.0 days and p re-ov ipos ition to 6.2 - 7.7 days.W ith this diet, a m illion pupae cost US$ 2'5 - 30. The medium was dispensed in trays within muslin cloth cabinets. The eggs w ere seeded onto strips of paper tow elling la id on the surface of the medium and covered with new spaper. Larvae 8 - 9 days old w ere washed out of the medium and put in m oist sawdust fo r pupation.

Stock cages contained cotton bolls saturated with a m ixture of sugar, yeast hydrolysate and water. P la s tic cups perfora ted with a needle served as oviposition substrates from which the eggs w ere brushed or rinsed out.

Population dynam ics and d ispersa l w ere studied by trapping in a sem i­iso la ted 150-ha mango plantation. B efore deciding on the trap design to be used, the Steiner, Nadel, Sticky W ing and a lo ca lly designed trap w ere com pared in a 20-ha mango orchard. The lo ca l trap is a cy linder (d iam eter3.5 in; length 6 in ) of screen w ire (0.5 in) with both ends fitted with sem i­c irc le s of the same w ire: suspended in its m iddle is a dental r o l l baited with m ethyl eugenol/ insecticide. The cylinder is p laced inside a perforated polyethylene bag which is then suspended horizon ta lly . The insects trapped can be co llected by s im p ly rep lacing the bag. Th is trap, which costs only US$ 0.075, proved com parable to the Steiner trap which was the best. T h ere fo re , a screen of 80 such traps was established in the la rg e r plantation and s e rv iced w eek ly during January — Septem ber 197 3. Results show that the population abruptly in creased in M arch, reached a peak in A p r il and th erea fte r gradually declined.

PROGRESS REPORTS 125

In s te r iliza tion studies, a G am m acell 220 was used to irrad ia te the pupae2 days be fo re em ergence with dosages ranging from 1 to 13 krad. None o f these doses had any substantial e ffec t on % em ergence and sex ratio.P a irs made up o f an irrad id ted fem ale with a norm al m ale and v ic e ve rsa w ere segregated and th e ir longevity , fecundity and fe r t i l i ty w ere measured.A t doses below 13 krad, longev ity was norm al. A t 3 krad fecundity was norm al when the m ale only was trea ted but d rastica lly reduced when the fem ale was irrad ia ted . F em a les treated with 5 - 1 3 krad did not lay eggs whereas fecundity was norm al when the m ales w ere irrad ia ted with doses below 13 krad (at this dose fecundity dropped concom ittantly with longevity ). Both pa ir combinations w ere com plete ly s te r ile at doses from 5 to 13 krad.

STUDIES ON THE MEXICAN FRUIT FLY Anastrepha ludens LOEW

D. Enkerlin SInstituto Tecnológico y de Estudios Superiores de Monterrey,Monterrey, N .L ., Mexico ,

The fo llow ing g ives the salient resu lts of the w ork ca rr ied out on the M exican fru it f ly from 1971 to 1973.

In attempts to determ ine the optimum technique fo r im m ob iliz in g A. ludens adults, a cold treatm ent (6°C ± 5) and exposures to C 0 2 and N2 w ere com pared fo r th e ir e ffects on the tim e requ ired fo r recuperation, fecundity, fe r t i l i t y and longevity. Adults w ere exposed to these treatm ents fo r 15, 20, 25 and 30 min: none of the treatm ents proved idea l, C 0 2 having a m ore detrim enta l e ffec t than the others.

In irrad ia tion studies, jvhen m ales from pupae trea ted with gamma rays w ere crossed with norm al fem a les , egg s te r ility increased from 37% at 0.5 krad to 100% at 6.0 and '8.0 krad; fem ales trea ted with 2 krad or m ore did not lay eggs. F lie s treated with 6 krad are being re leased in a suppres­sion program m e in Baja C a liforn ia N orte on the M exican-US border.

B ioc lim atic cabinets w ere used to study the developm ent o f a ll stages of the M exican fru it f ly under various reg im es of tem perature and light;RH was not controlled. The range fo r tem perature was 18 - 28°C and fo r illum ination 10 - 14 h. Eight d ifferen t combinations w ere used including a stepw ise decrease in both factors . It was found that la rv a l developm ent was fastest and pupal y ie ld ¡highest under a constant reg im e of 28°C and 14-h photoperiod. Howeverj, adult em ergence was highest at 2 3°C and 12-h light throughout. Under allj conditions studied, the sex ra tio was somewhat in favour of the m ales.

Puparia w ere d issected on each successive day o f the pupal deve lop ­ment and exam ined m orpholog ica lly to determ ine when the pupa is form ed.No c lea r-cu t d ifference could be found in between the successive stages inside the puparium, and developm ent appears continuous; thus fa r , there is no evidence of a diapause.

Six compounds (terp in ÿ l acetate, lina lo l, beta ionone, edeom a and extracts of Chapóte am arillo and Schinus in M cPh a il traps w ere tested fo r th e ir attractiveness to A. lúdens adults re leased 90 - 100 m from the traps. The checks w ere another s im ila r six traps baited with cotton seed hydrolysate. The hydrolysate proved a fa r superior attractant.

SEIBERSDORF CONTRIBUTIONSi

Contributions from staff of the Seibersdorf Laboratory, IAEA, Vienna

DECISION MAKING IN PEST CONTROL PROGRAMMES

B . A . B u tt

Introduction I

In planning a pest control programme, one must make a decision, using all available information, on what method or combination of methods of pest control w ill be used. This paper presents a systematic method1 for reaching this decision by using a hypothetical situation and going through the steps for reaching a decision.

Situation

The golden fruit fly has been found in citrus near the airport in the city of Atoma. The citrus of Atoma has no market value, but the citrus-lined streets a re a tourist attraction. The area is also famous for its unusual speciality fruits.

About 200 km west of Atoma is a 50 X 106 US dollars/year citrus industry. The pests attacking this citrus are held below economic levels by biological control and no ¡pesticides are applied; as a result, the non­sprayed fruit is sold at a premium. If the golden fruit fly reaches this area, pesticides w ill have to be used, thus reducing the market value of the fruit. The pesticides w ill also cause outbreaks of secondary pests, and therefore additional applications of pesticides w ill be required. The fruit growers fear that the golden fruit fly could destroy their industry and therefore have raised US $5jX 106 to eliminate the pest in Atoma before it reaches the commercial citrus growing area.

Procedure

F irst the objectives must be defined. In this case the objectives are to eliminate the golden fruit flÿ in Atoma before it reaches the commercial citrus area. This must be áone at a minimal cost and adverse affect on the environment. !

In choosing a method of achieving these objectives, resource limitations and required results that must be met are listed. If a method does not meet these "must objectives" it is no longer considered. A rea l sprays and host rem oval do not meet the "must objectives" (Table I) and therefore are no longer considered. 1

The objectives for the best use of resources and the maximum results with the minimal disadvantages are then listed. These "want objectives" are weighted 1 through 10, 10 being the most desirable. Each of the methods of control are then scored ojn a 1 to 1 0 scale for each of the "want objectives". These scores are then multiplied by the original weights assigned to each objective (Table I). The products are then totalled for each control method and compared. One can see that ground treatment and release of parasites were 266 and 259 respectively, whereas golden fruit fly attractant and thesterile-insect technique were 405 and 452 respectively.

i

‘ KEPNER, C . H . , TREGOE, B. B . , 'The Rational Manager, M cG raw-H ill, New York (1965).

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130 SEIBERSDORF CON TRIBUTIONS

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SElBERSDORF CON TRIBUTIONS 131

T ABLE II. E VALU AT IO N OF ADVERSE CONSEQUENCES OF VARIOUS CONTROL METHODS TO ELIM INATE THE GOLDEN FRUIT F L Y IN АТОМ А

Ground treatment with Malathion bait

1. Some residents may refuse to allow spray

crews into gardens ; Probability

Seriousness

P x S

1 0

80

2. Tourists complain o f spray odour

and spots on cars ProbabilitySeriousness

P x S

Sterile-insect technique

IFlies must be produced in nori-host area Probability

Seriousness

10

4

Total

40

40

Release o f parasites

Parasite not e ffec tive in cool

weather which occurs in some years Probability

Seriousness

P x S

310

30

30

Golden fruit fly attractant j

1. Recent research shows that the golden

fruit f ly attractant is also highly attractive to the key pollenators o f the speciality fruits produced in Atoma Probability

Seriousness

10

10

2. The odour o f the golden fruit fly

attractant is o ffensive to somè people Probability

Seriousness

P x S 40

3. Tourists steal traps ProbabilitySeriousness

132 SEIBERSDORF CONTRIBUTIONS

Now the possible adverse consequences of each control method must be listed. The probability and seriousness of each of these are rated 1 through 10. The probability and seriousness scores are then multiplied and the sums of the products for each control method are compared (Table II). The figures developed in the adverse consequences cannot be subtracted from the performance total of the want objectives, but must be compared separately.

Decision

Two control methods, sterile-insect technique and golden fruit fly attractant, have very high performance ratings; however, the golden fruit fly attractant has very serious adverse consequences. Therefore, the sterile-insect technique should be used to eliminate the golden fruit fly from Atoma.

PRACTICAL PROBLEM ANALYSIS OF A STERILE FRUIT FLY RELEASE PROGRAMME

B.A. Butt

Any operational programme, whether simple or putting a man on the moon, requires detailed planning in advance. Problem s are best solved by preventing them; however, potential problems must be identified and contingent plans developed. This paper presents a problem analysis of a typical sterile fruit fly release programme. An analysis of a specific programme would differ as would the probability and seriousness of a problem.

The reader w ill note that "trained personnel" and "monitoring" or "quality control" appear a number of times in the analysis. The need for well-inform ed and well-trained personnel as well as a detailed monitoring and quality control system cannot be over-emphasized.

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TAGGING OF ADULT MEDITERRANEAN FRUIT FLY, Ceratitis capitata (WIEDEMANN). WITH RUBIDIUM

A. Wehrstein

When large numbers of marked insects are needed, e .g . in release/ recapture studies, tagging with radioisotopes is inconvenient. Dyes may affect the performance of the marked insect. As an alternative to these techniques we tested detection by absorption spectroscopy of rubidium in adult medflies.

The m arker was administered as rubidium chloride at various concen­trations either in the standard larval medium or in the diet of the newly emerged adult. Fo r detection of the m arker, the adult flies were killed by cooling and ashed at 500°C for 5 h. The ashed sample was dissolved in0.5 ml of 0. IN perchloric acid with little heating. One ml or more of acid was used to rinse the crucible. This solution was transferred to glass ampoules and then read directly with the atomic absorption instrument. Results are presented in Tables I - III.

Table I shows that on day 0 the rubidium concentration in the treated fly increased with the level of the m arker in the diet; thereafter, the detectable amount of rubidium dropped rapidly and levelled off between days 11 and 22. The biological half-life was about 2 days.

Table II shows the average amounts of rubidium detected in larvae, pupae, puparia and teneral flies when the m arker was administed in the larval medium.

Table III gives the average amounts of rubidium detected in 48-hour-old flies fed during that period various concentrations of the m arker in 1 0 % aqueous sucrose solution.

T ABLE I. AVERAGE AMOUNTS 3 OF RUBIDIUM IN M ED FLY ADULTS REARED AS LARVAE ON DIETS CONTAINING VARIOUS CONCENTRATIONS OF THE MARKER

DayAmount o f rubidium in the diet in ppm

0 500 1000 2000

0 0.1083 ± 0.0248 7.3305 ± 0.6038 11.6422 ± 0.5186 20. 9002 à 2. 9028

2 0.0759 ± 0. 0016 2.2680 ± 0.8825 5.0780 ± 1.0837 10.1404 ± 4. 0794

8 0. 0728 ± 0. 0217 0.7354 ± 0.2322 0.7663 ± 0.4180 3.3053 ± 3.2279

11 0. 0449 ± 0. 0147 0.2709 ± 0. 0774 0.3716 ± 0.1858 0.4412 ± 0.1703

18 0. 0464 ± 0.0132 0.2322 ± 0.1161 0.2554 ± 0.1006 0.9831 ± 0.9599

22 0. 0774 ± 0. 0286 0.2632 ± 0.1084 0.5186 ± 0.1626 0.4954 ± 0. 0697

a (x i S. D. ) jjg/adult m edfly

S'HBERSDORF CON TRIBUTIONS 137

T A B LE II. AVERAGE AMOUNTS 3 OF RUBIDIUM D ETECTED IN LAR VAE , PU PA E , P U P ARIA AND T E N E R A L FLIES W HEN MARKER IS INCLUDED IN THE LA R V A L MEDIUM AT VARIOUS CONCENTRATIONS

OrganismAmount o f rubidium in the diet in ppm

500 1000 2000

Larvae (3rd instar)

Fresh pupae

N ine-day old pupae

Puparia

Ten eral flies

11.1058 ± 0.4021

12.1207 ± 0.9691

10.7670 ± 0.5262

2.3304 ± 0.1921¡7.3305 ± 0.6038

15.9089 ± 1.1506

17.3708 ± 3.2813

16.5704 ± 1.5568

3.2641 ± 1.9737

11.6422 ± 0.5186

19. 8388 ± 1.2113

23.9982 ± 2.6075

23.6992 ± 3.7702

5.7671 ± 0.7696

20.9002 ± 2. 9028

a (x ± S .D .) fjg/organism

T A B LE III. AVERAGE AMOUNTS 3 OF RUBIDIUM DETECTED IN TW O - D A Y -O LD A D U LT MEDFLIES FED RUBIDIUM CHLORIDE DURING FIRST 48 HOURSb !

Amount o f rubidium in adult diet in ppm

500 1000 2000

Flies not washed

Washed

117. 8 ± 1.9

■ 17. 6 ± 4 .5

26.3 ± 5 .5

30. 0 ± 5.3

43.6 ± 8.8

47 .8 ± 13.2

3 (x ± S .D . ) (Jg/fly. k in ltP ]o aq. sucrose solution.

REARING OLIVE FLY AT SEIb'eRSDORFi

Anne Tischlinger

The following.is a description of the methods and equipment used for maintaining stock colonies: of the olive fly.

The adult flies are maintained in rotating cylindrical sleeve cages (36 cm in diameter, 190 cm high) at the rate of 500 females and 100 males per cage. Each cage has six wax cones for oviposition. The flies are fed a 4 :1 mixture of carbohydrate (sucrose: 9 parts; fructose: 1 part) and yeast hydrolysate. W ater is offered separately through wicks. At the end of 6 weeks the cage is discarded.

Eggs are collected daily, washed for 2 min in 1% formaldehyde, rinsed with distilled water and held over distilled water in cups with nylon-cloth bottoms until used.

138 SEIBERSDORF CON TRIBUTIONS

(1) Ingredients present in targe amountsSoy hydrolysate Yeast hydrolysate Vanderzant's vitamins Wesson's salts

(3) Suspensionadded gradually to mixed powders

Ingredients present in small amountsPotassium sórbate'] blended w ith

I approx. 2 litres f tap water J for 2 min

Mixed until smooth liquid preparation obtained. Some more water added

Non-oily suspension

(4) Sugar added.— Further mixing

(5) Olive and linseed oils added. ___ Further mixing

Aqueous/oily suspension (non-emulsified)

Aqueous/oily suspension (non-emulsified)

(6) Yeast and more water added. ___ Further mixing

(7) Cellulose and remaining water (containing hydrochloric acid)

___ added alternately

Solid medium

FIG. 1. Preparation o f o liv e fly larval medium.

The composition of the medium used for larval rearing is shown in Table I. The preparation sequence of this medium is indicated in Fig. 1.The ingredients are mixed in a cement mixer and then remixed in a house­hold m ixer to obtain proper texture. The medium is dispensed into paper cups at the rate of 100 g/cup. Each cup is inoculated with about 435 eggs in a very sm all volume of distilled water and the cup is closed. The cups are held at 25°C and, after 8 days, small holes are punched in the bottoms to allow the mature larvae to leave the medium for pupation. Pupation takes place in bran placed in trays below the cups.

SEIBERSDORF CON TRIBUTIONS 1 3 9

TABLE I. INGREDIENTS IN ONE KILOGRAM OF SOLID LARVAL DIET

Wat ex

O live o il

Potassium sórbate

Nipagin

Aureomycin

Sugar

Linseed o il

Brewer’s yeast (dried)

Soy hydrolysate

Yeast hydrolysate

Vitamins (Vanderzant)

Cholesterol

Wesson's salts

IN HCl

Cellulose

480 ml

80 ml

0 .5 g

1. о OQ

50. 0 mg

40 g

3 ml

100 g

30 g

10 g

10 g

1 g

5 g

adjust to pH 4. 0

227.5 g

Larval development is completed in 10 - 16 days, the mortality being 70 - 75%. The individual pupal weight varies from 2.9 to 5.6 mg. Adults emerge after another 10 - 11 days at the rate of 20 - 70%.

ADULT OLIVE FLY DIETS: A COMPARISON

A. Wehrstein

1 4 0 SEIB ERSDORF CON TRIBUTIONS

The effects of six diets for adult olive flies on the fecundity, fertility as well as the male and female longevity of this species were compared. Five of these diets have been used by other workers, one was formulated in Seibersdorf. The composition of the diets and their origin is shown in Table I.

To ensure uniformity, the flies were fed these diets during the same period and under the same conditions. The flies were kept in small, round, plastic cages with a concentric wax cylinder for oviposition. Each cage contained 30 females and 5 males; there were 2 cages/diet. Food was presented on filter paper strips hanging from the ceiling of the cage; it was renewed daily. A sugar cube and distilled water were also present and renewed as required. The results are shown in F igs 1-6. According to these data, diet F was optimal as it resulted in a reasonable longevity combined with high fecundity and fertility.

T A B LE I. DIETS USED BY D IFFERENT INVESTIGATORS FOR ADULT OLIVE FLIES

A В С D E F

Seibersdorf Moore(1959

Hagen

et al.

(1963)

Santas

(1965)

Economopoulos

and

Tzanakakis(1967)

Orphanidis et al.

(1969)

Water 10 50 50 50 50 10

Yeast hydrolysate

(enzym atic)

10 10 10 10 10

Partially

hydrolysed protein3

10

Brewers yeast 30

Sucrose 36 40 40 20 40

fructose 4

Honey 20 50

Egg yolk 7

Choline chloride 0.05 0. 05 0.05

Streptomycin

sulphate

0.25

a Probably yeast hydrolysate (enzym atic).

LA

RV

AE

SEIBERSDORF CONTRIBUTIONS 141

DAY S /¡lF T E R E M E R G E N C E O F F L IE S

FIG. 1. Mean larval production per 30 females, -i— diet A

, j . . . diet В

■ j " - diet С x x x diet D

— diet E • • • diet F

EG

GS

142 SEIBERSDORF CON TRIBUTIONS

FIG. 2. Mean egg production per 30 females. (Legend for curves as in Fig. 1).

2 4 6 8 10 12 14 16 16 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

D A Y S A F T E R E M E R G E N C E O F F L I E S

FIG .3. Number o f eggs per fem ale per day. (Legend for curves as in Fig. 1).

MO

RT

AL

ITY

(%

) EG

G H

AT

CH

(V

o)

SEIBERSDORF CON TRIBUTIONS 143

FIG .4. Per cent egg hatch. (Legend for curves as in F ig . l ) .

100

90

80

60

50

40

30

2 0

10

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

D A Y S A F T E R E M E R G E N C E O F F L IE S

FIG. 5. Female mortality. (Legend for curves as in Fig. 1).

144 SEBERSDORF CON TRIBUTIONS

1 0 0

90

80

5? 70

% 60

<о 50 2

¿ 0

30

2 0

10

2 4 6 8 10 12 U 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

D AY S A F T E R E M E R G E N C E O F F L IE S

FIG. 6. M ale m ortality. (Legend for curves as in Fig. 1).

R E F E R E N C E S

ECONOMOPOULOS, A .P . , TZAN A K A K IS , M .G . , Egg yolk and o live ju ice as supplements to the yeast

hydrolysate-sucrose diet for adults o f Dacus o lea e , L ife Sci. £ (1967) 2409.

HAGEN, K .S . , SANTOS, L. , TSECOURAS, A. , "A technique o f culturing the o liv e fly , Dacus o leae Gmel. ,

on synthetic media under xenic conditions” , Radiation and Radioisotopes Applied to Insects o f Agricultural

Importance (Proc. Symp. Athens, 1963), IAEA, Vienna (1963) 333.

MOORE, I . , A method for a rtific ia lly culturing the o live fly (Dacus o leae Gmel. ) under aseptic conditions, K tavim 9 (1959) 295.

ORPHANIDIS, P. S ., PETSIKON, N . , PETSEKOS, P. G . , Eléments sommaires concernant un élevage

expérimental du Dacus de l 'o l iv e sur substrat a rtific ie l, In 8th FAO ad hoc Conference on the Control o f O live

Pests and Diseases, Athens, 8 -1 2 May 1969.

SANTAS, L. A . , On a new synthetic nutritive substrate for rearing larvae o f Dacus o leae Gmel. (Diptera-

Tryp itidae), Bull. Agr. Вацк Greece 144 (1965) 8.

LIQUID LARVAL DIET FOR THE OLIVE FLY Dacus oleae GMEUN

A. Mourad

SEIBERSDORF CONTRIBUTIONS 145

Various absorbent materials were tested with the liquid diet developed by Mittler and Tsitsip is1. The absorbents were cotton wool, cotton and paper towelling. These were autoclaved at 120°C for 45 min and then put in 20 cm X 12 cm X 10 cm plastic boxes rinsed in 70% ethanol for asepsis. The bottom of each box was perforated with 50 2 -m m -diam eter holes. The holes were masked with tape until the larvae were ready to pupate. Pupation took place in bran provided below the boxes.

The liquid diet was poured onto the substrates in the boxes to give 3 - 6 g diet/g substrate. After infestation with eggs, the boxes were kept tightly shut in the dark at 25°C for 12 days. Under the conditions described, the development of fungi and other m icroorganism s was a problem.Results are shown in Table I.

T ABLE I. E VALU AT IO N OF THE M ITTLER-TSITSIPIS LIQUID DIET ON VARIOUS SUBSTRATES

SubstrateNo. o f eggs

plantedEggs/gdiet

Mean No. o f

pupae

Mean pupal

weight

Mean °]o emergence

Cotton wool 500 20 105 5.3 48

200 8 109 6.0 78

Cotton towel 500 25 87 5.1 51

200 10 87 5.3 47

Paper towel 500 18 25 4 .4 17

200 10 12 4.2 10

1 MITTLER, T .E . , TSITSIPIS, J . , 1973. Economical rearing o f larvae o f the o liv e fruit fly , Dacus o lea e , on a liquid diet offered on cotton towelling, Entomol. Experim. Appl. 16 (1973) 292.

STATEMENTS AND RECOMMENDATIONS

GENERAL STATEMENTS AND RECOMMENDATIONS

1. The Panel considers fruit flies a major economic pest problem, especially in developing countries. New important fruit production areas are being threatened because some Trypetids are currently expanding their geographic distribution, e.g. the Mediterranean fruit fly in Central Am erica. Likewise, quarantine regulations often limit potential markets. Heavy reliance on insecticide applications has led to new problems in the manage­ment of agricultural pests, namely insecticide resistance, resurgence of secondary pests, undesirable chemical residues and environmental contamina­tion. The sterile-insect technique (SIT) is one of the few highly specific control methods which can be used to overcome these problems. As shown here and in previous panels, the effectiveness of this technique has been demonstrated in quarantine, economic suppression and eradication, thereby stimulating research on target species which otherwise might not havebeen carried out.

2. The prominent role of the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture in promoting the development and application of the SIT for the control of fruit flies is recognized and highly commended by the Panel. The emphasis in this work has been predominantly for the benefitof the developing countries but the impact also has been felt in more techno­logically advanced countries. Therefore, the Panel strongly recommends that the Joint Division continue and expand its programme of fruit fly suppression by the SIT.

3. In view of the budgetary constraints limiting the assistance the Joint Division can render, the Panel strongly recommends the appropriation of monies for the establishment of a revolving fund. The sum required would be US $250 000 annually, to be administered by the Joint Division for the specific purpose of assisting member nations in the control of fruit flies by the SIT. Such a fund would permit a developing country with an ongoing programme, but lacking the funds for bringing it to completion, to obtain the necessary support.

4. In the urgency to develop alternatives to pesticides, entomologists have tended to embark too rapidly on ad hoc release programmes frequently aimed directly and solely at eradication. Other possibilities such as the integration of the SIT with chemical methods and the use of the techniqueas a tool in pest management are only now receiving greater attention.

A good example of the judicious integration of the SIT in a pest manage­ment scheme for eradication is the Peruvian medfly project. A recent UNDP study1 supports the concept that eradication of the medfly in isolated valleys in Peru using the SIT in an integrated approach with insecticides is technically feasible and economically sound. The Panel fully supports the UNDP study team recommendations and urges that they be implemented.

1 BRAZZEL, J.R ., DAVIS, V .M . (1973), Peru Fruit Fly Eradication, Report o f the Evaluation Mission, UNDP, 46 pp + 4 annexes.

149

150 STA TEM E N TS AND RECOM M ENDATIONS

5. The Panel feels that the SIT is a tool to be used with discrimination.Its hasty application led and still leads to neglecting or awarding low priority to the collection and utilization of biological information. In this connection, the Panel considers ecological and behavioural information tobe of particular importance. In addition, the Panel also strongly recommends to member nations and the Agencies involved to conduct economic analyses before commencing large -sca le SIT practical control programmes.

6 . Whenever technical assistance is requested by member nations for la rge -sca le fruit fly control by the SIT, economic analysis of the situation should be a sine qua non condition. In this connection the Panel noted that the OIRSA2 member nations are showing active interest in the eradication of the medfly from Central Am erica and that the economic analysis com­pleted in 19723 confirmed the project's feasibility. The Panel wishes to point out, however, that this project would only be successful if the following conditions were met:

( 1 ) availability of the basic biological information;( 2 ) proper planning on which to make sound decisions;(3) utilization of suitable numbers of trained personnel for the needed

programme operations;(4) establishment of a quality control system;(5) continuous operation of a parallel research programme, and( 6 ) adequate funding. 4

7. In addition to economic data, the Panel re-em phasizes the need for due consideration of alternative methods such as male annihilation, olfactory and visual attractants, inundative releases of parasites, etc. The Panel strongly recommends the preparation of a weighing scheme including the above criteria to arrive at a decision whether, in a given situation, the SIT should or should not be used.

8 . The Panel expressed concern that although the sterile-insect technique had proven to be an effective pest management tool, its use has largely been restricted to relatively few countries. Utilization of the technique is still mainly in the hands of researchers. Ultimately the responsibility for widespread field use lies with regulatory, control and extension officials. These officials are largely unaware of how the technique can be integrated into a nation's ongoing pest management programme. The Panel recommends that training offered through the F AO/UNEP project on Integrated Pest Control be expanded to include national and regional symposia to educate these officials. These symposia would be followed by training courses to prepare national field workers in the day-to-day technical programme requirements. Expert input into this training programme would originate with the Joint FAO/IAEA Division.

2 Organismo Internacional de Sanidad Agropecuaria, including Costa Rica, El Salvador, Guatemala,

Honduras, M exico, Nicaragua, Panama.3 HENNING, R .G . et a l. (1972), An Economie Survey o f the Mediterranean Fruit Fly in Central Am erica,

USDA Field Report 21, 81 pp.4 A t the tim e o f going to press, this project took a new urgency as the m edfly is reported close to

M exico; see also R. H. Rhode, Appendix I o f these Proceedings.

STATEMENTS AND RECOMMENDATIONS 151

9. During the proceedings it became clear that certain research projects in progress in specialized laboratories in various parts of the world are of particular relevance to the efficient and intelligent application of the SIT (e.g. research in allozymes, acoustical analysis and behavioural studies). Most frequently this work is pursued in developed countries and it is suggested that relevant member governments be strongly encouraged to provide adequate support to those projects. It is recommended that those specialized laboratories be available to support SIT projects in developing countries (see also paragraphs 17 and 19).

10. The Panel noted the present status of Research Contracts and A g ree ­ments on fruit flies and felt that a better balance is needed in their distribution. Thus the Panel recommends that the number of Research Agreements be increased in order to stimulate the already mentioned (paragraph 9) supporting scientific activities carried out in technologically advanced countries.

11. Upon review of the recommendations of the FAO/IAEA Expert Panel on the Practical Use of the Sterile-M ale Technique for Insect Control (Vienna, 13 - 17 November, 1972)5, the present meeting endorses and re-em phasizes recommendations for continued awareness regarding fitness, competitiveness and prevention of genetic and physiological deteriorationof m ass-produced fruit flies. Likewise, the present Panel recommends that the Joint Division act as a centre for the development of methods to evaluate artificial diets for efficient mass rearing, to evaluate mass rearing techniques and to provide guidelines for the application of these methods in developing countries. Thus, the following are recommended as the prim ary objectives for the Joint Division's programme on fruit fly suppression by the SIT:

(a) development of methods for the testing of media and other links in the fruit-fly production chain;

(b) improvement of irradiation methods;(c) development of quality control techniques;(d) improvement of logistics (devices and methods);(e) training personnel.

12. A prim ary requirement of the SIT is the designing of experiments for mass rearing and to determine the quality of the insects produced both for breeding stocks and for irradiation and release. Implementation of the recommendations in paragraph 1 1 w ill require collaboration between two research professionals: an insect nutritionist and a specialist in behavioural physiology, both being experts in experimental design.

The nutritionist w ill carry out research on the nutrition of target species and develop therefrom experimental procedures for the evaluation of diets. The result of this work w ill appear in publications and will be used in the training of fellows from developing countries. This work will be done in constant co-operation with the behavioural physiologist so that a trainee w ill have the benefit of experience in nutrition, the formulation of diets and the development and conduct of some simple behavioural tests for evaluation of insect quality.

5 The Sterile-Insect Technique and its Field Applications, Panel Proceedings, IAEA, Vienna (1974).

152 STATEMENTS AND RECOMMENDATIONS

A further task of the behaviourist w ill be to collate information on quality-control research carried out in other locations. At the termination of his employment, this professional's experience and the information collected w ill be published in a laboratory and field manual.

The Panel further recommends that project leaders collaborate by corroborating under their own field conditions some of the techniques developed at the Agency.

13. The Panel recognizes that a problem exists as regards placementof trainees from developing countries due to the limited number of centres with ongoing programmes of fruit fly control by the SIT.

It is recommended that the allocation of trainees from developing countries be not restricted to ongoing projects but that use be made of the large number of existing centres of form al instruction.

The Panel recommends that the present level of training activities at the Seibersdorf laboratory be maintained and if possible increased.

14. The Panel noted with concern that in some developing countries Agency publications in entomology are not passed down from the administrative to the working level. Therefore, the Panel recommends that the Agency explore ways to ensure dissemination of its publications in entomology(in particular Panel Proceedings) so that they reach the maximum possible number of researchers in developing countries.

SPECIFIC STATEM ENTS AND RECOMMENDATIONS

Operational aspects of fruit fly control by the sterile-insect technique

15. Having considered the minimum size area over which practical fruit fly control by the SIT could be expected, the Panel concluded this could not be determined with any degree of precision because of the numerous variables involved. Assuming adequate quarantine control, manpower, fly production and release capability, a key factor is the degree of isolation. Other factors which may impose a limit in effectiveness are the level of control by bait sprays, clean cultivation, and the degree of freedom given to the project manager in the implementation of the programme.

16. The Panel also examined the question of sterile stings by released females, possible counteraction by releasing males only and the beneficial role, if any, of the sterile female. The Panel considers sterile stings a marketing problem. The importance of those stings varies with the fruit fly species, the type of fruit (it may be important in some stone fruit and citrus varieties) and the time of the year. If the stings are a problem in experi­mental studies, the fruit may have to be bought. However, the problem is temporary where eradication is the goal and can be diminished by such methods as stopping or reducing releases before susceptible fruits come into production, by suitable cultural practices and selective spraying of early ripening varieties. Currently no feasible method exists to separate the sexes in large numbers; research to find methods to do this economically (e.g. by use of sex distortion) should be encouraged. The evidence thusfar available suggests that, in fruit fly species with polygamous behaviour, the release of sterile females contributes to suppression.

S TA TEM E N TS A N D RECOM M ENDATIONS 153

17. The Panel considers of paramount importance developmental research in quality control and quality control techniques. This is essential for determining the most important biological parameters for sterile fly releases. Such techniques w ill allow the early screening of the flies best suited for a field programme as well as the continuous monitoring of the effectiveness of the released flies. Quality control techniques are needed for each fruit fly species. Since there are laboratories specialized in studies on quality control of m ass-reared insects, the services of these laboratories should be utilized in SIT programmes.

18. A measurement of the effectiveness of sterile flies in mating with wild flies is essential. This may involve various aspects of mating behaviour. Once known, these can be used to develop monitoring systems in a sterile-insect release programme. More field studies are needed on the mating behaviour and ecology of fruit flies. In this respect, male flies with sperm marked by radiotracers may be released in field experi­ments to establish mating frequency and competitiveness under natural conditions.

Radiotracer sperm tagging is necessary for special applications, but the Panel does not consider it essential for general use during a sterile release programme.

19. The Panel recommends that the Agency assist and co-ordinate studies of fruit fly behaviour and ecology as related to the SIT. Monitoring genetic variability (e.g. by allozyme analysis) is essential as an alarm system to warn of increasing homogeneity in the breeding stock; the Panel recommends that this be done in a central location to which sample m aterial could be sent.

20. Where a fruit fly pest management programme calls for a multidis­ciplinary approach, including extension and regulatory practices, the Panel recommends that the SIT be integrated with other suppression methods, such as male confusion and male annihilation, the judicious use of bait sprays, trapping, parasites and predators.

21. The Panel considers the airplane an essential tool in la rge -sca le control and eradication programmes and therefore strongly recommends that provision be made to include this piece of equipment at the beginning of such program m es. In this connection improvement and evaluation of aeria l release techniques are required. In sm aller program m es, before deciding on air re leases, due consideration should be given to economic factors, such as size of the area, cost of labour, environmental conditions and topography.

22. A further need is some automation to reduce human e rro r, increase the quality of the product and lower costs. The Panel recommends that resources be allocated to the development of such devices, particularly in la rge -sca le projects requiring around-the-clock work.

23. The Panel had before it a scheme designed to assist in the process of decision making^ in the conduct of an SIT programme. Such a scheme

6 S e e B .A . Butt, these Proceedings.

is strongly recommended for the consideration of those contemplating the application of the SIT.

Mediterranean fruit fly Ceratitis capitata (Wiedemann)

1 54 STATEMENTS AND RECOMMENDATIONS

24. Information available from various medfly rearing units (Costa Rica, Cyprus, Israel, Italy, Spain, Austria) allows an approximate calculation of the space requirements for mass producing the medfly. The present norm is approximately 50 000 to 60 000 insects per week per m2 total rearing facility surface (i.e. irradiation and storage rooms, office, etc. included).

2 5. Production of the medfly is still relatively expensive because of costly nutrients such as protein hydrolysate and b rew er's yeast. In most cases these ingredients are imported and in developing countries this often is a drain on hard currency. Therefore, the Panel strongly supports the current Joint Division studies on the replacement of expensive nutrients by inex­pensive and readily available materials. The Panel also recommends that the Joint Division encourage sim ilar work in developing nations.

26. Regarding winter releases of sterile medflies to protect citrus, the Panel considers this a good approach if the climate does not inactivate the insects, there is mating, the population is low, and the market value of the fruit is not reduced by sterile stings.

27. The Panel recognizes that the effectiveness of the SIT for medfly control during spring and summer has been repeatedly demonstrated, e.g. in Spain, Italy and Israel. Good results also were reported after combining this technique in pest management with chemical and biological control agents, e.g. in Argentina and Peru. However, to convince administrators to put this technique into practical use, a demonstration of eradication could be decisive. Therefore, the Panel urges the FAO/IAEA to co-ordinate a campaign of medfly eradication in a Mediterranean country drawing uponthe expertise and pooling the resources of several countries in the area.The assistance of the International Organization of Biological Control in such a venture should be enlisted (see Appendix II).

Olive fly, Dacus oleae (Gmelin)

28. The biotechnology fo r olive fly production is steadily improving. According to information from Greece the present olive fly production norm is approximately 5 000 pupae per week per m2 total rearing facility surface.

29. The present cost of olive fly production in Greece is US $1/1 000 pupae, labour included. The Panel is not convinced that cost should be a prim ary consideration in substituting imported nutrients for locally available ones because imported products are more standardized and thereforetheir use in the various rearing facilities would eliminate a source of variation and increase the validity of comparisons. Nevertheless, the Panel recommends that the Joint Division obtain a list of materials used in olive fly rearing.

ST A T EM E N T S AND RECOM M ENDATIONS 155

30. The Panel recognizes that the SIT can and should fit into a pest management system for olive fly control. Because of a lack of geographical isolation, eradication usually w ill not be the objective of the SIT in olivefly suppression programmes. The pest management scheme should comprise two sequential phases:

(1) Suppression: by cultural practices (spring collection of remaining fruits), treatment with selective insecticides (early summer), trapping (pheromones included);

(2) Control: by release of sterile olive flies in combination with parasites.

31. The co-operative Yugoslav/Joint Division/USDA olive fly research programme, including the development of better irradiation techniques, mass rearing, marking, trapping, release methods, diets, etc., complements research in other olive growing countries. The Panel notes that the Agency supplies olive flies of Greek origin to Yugoslavia for ecological studies;it suggests that releases of a Yugoslav strain would be preferable.

32. The Panel recommends increasing the number of contracts, and if possible, the monetary value of contracts, for research on olive fly rather than on medfly.

33. Training in olive fly research should take place in olive-zone labora­tories wherever this research is sufficiently advanced.

34. The Panel recommends that the Joint Division, together with organizations such as the International Biological Program m e, the International Organiza­tion of Biological Control and the European Economic Community, encourage and help organize annual or biennial meetings of olive fly workers to exchange information. These meetings should rotate between major olivefly research centres (Italy, Greece, Yugoslavia, Spain, Portugal).

35. The Panel recommends an exchange of visits between Agency personnel engaged in developmental research on olive fly and their colleagues in the olive zone to improve co-ordination.

Other fruit fly species

36. In the developing countries some of the most important fruit fly species are:

Anastrepha ludens: Mexican fruit fly;A. fraterculus: South American fruit fly;A. suspensa: Caribbean fruit fly;Ceratitis rosea : Natal fruit fly;Dacus dorsalis: Oriental fruit fly;D. cucurbitae: Melon fly;D. zonatus: Mango fruit fly;Rhagoletis cerasi: Cherry fruit fly.

156 STA TEM E N TS AN D RECOM M ENDATIONS

37. In the developed countries, several species of Hylemya are of economic importance to vegetable crops and, based on the experience obtained in Belgium and Holland, could be considered in the near future as target species for the SIT.

38. The Panel feels that the developmental work in several research centres on the species listed is adequate and need not be undertaken by the Joint Division. However, the Joint Division could greatly contribute in the II. cerasi programme by co-ordinating the work of European researchers.

39. The Panel considers that the use of local materials after their extensive evaluation may be the only economical and practical solution to mass rearing the other fruit fly species just mentioned. It is recommended that the Agency assist and/or co-ordinate the evaluation of such materials.

40. Likewise, as regards some of the species listed, the Panel recommends that the Agency encourage co-ordination among different workers on specific topics such as radiobiology, rearing, ecology, release methods, etc.

41. It is recommended that the Agency continue to train scientists on the fruit flies listed here.

Anastrepha ludens

42. The 1969 Panel on the Sterile-M ale Technique for Control of Fruit F lies 7

recommended that an eradication experiment be conducted in an isolated area of about 1000 km2. Steps have been taken in this direction but on a somewhat sm aller scale. However, since the exact distribution, ecology and host relations of this pest in Mexico and Central Am erica are not known, work on these aspects should be encouraged. Likewise, the application ofthe SIT in conjunction with other control measures should be more extensively considered.

Anastrepha fraterculus

43. Research on this species is sufficiently advanced to make a study of the effectiveness and ecological implications of simultaneously releasing A. fraterculus and Ceratitis capitata worthwhile. This would be a unique opportunity for testing the possibility of simultaneously suppressing or controlling several species by the same technique and exploring possible interactions of such a suppression.

Anastrepha suspensa

44. The study of this species has greatly progressed in the USA. Other countries in which this fly is a problem should be encouraged to take maximum advantage of these studies.

As they become of economic importance, other Anastrepha species might be considered for inclusion in the Agency's programme upon requests from the affected countries.

1 Panel Proceedings Seríes. STI/PUB/276, IAEA, Vienna (1970).

STATEMENTS AND RECOMMENDATIONS 157

Dacus dorsa lis, D. cucurbitae, D. tryoni and D. zonatus

45. Methods of rearing, trapping and irradiation as well as sterility data and chemical control measures are available for these four species of Dacus. The feasibility of suppressing D. dorsa lis, D. cucurbitae and D. tryoni by theSIT has been demonstrated. Efforts should now be made to integrate the SIT in a sound pest management programme in large areas. W herever and whenever possible, eradication should be attempted.

D. dorsalis and D. cucurbitae have several hosts in common, even though they may not complete their life cycle in some. Again, there is an opportunity for studies of simultaneous suppression.

Release to establish "guardian population" barrie rs to prevent infestation or reinfestation of fly -free areas should be undertaken.

Since much work has been done on D. tryoni, contact with workers on this insect should be maintained.

Rhagoletis cerasi

46. This species is of great economic importance in certain countries and is widespread, attacking a high percentage of fruit if no control measures are applied.

Research on R. cerasi now shows that in the near future the eradication of this pest can be proven at least in some rather isolated areas.

Suppression of this pest by the SIT should be studied as part of a pest management project.

Especially in the case of this insect, the Panel strongly recommends that the Agency further personal contacts between all workers concerned.

Hylemya spp.

47. The feasibility of suppressing H. antigua by the SIT has been demon­strated in the Netherlands. The Panel recommends that the Agency encourage further basic and applied research in developed countries on this and other Hylemya species, such as H. brassicae. Large -sca le field trials should be initiated as soon as mass rearing and ecological studies have developed to a suitable level.

APPENDIX I

A MEDFLY ERADICATION PROPOSAL FOR CENTRAL AMERICA*

R.H. RHODE Citrus Insects Investigations,

USDA, ARS, Weslaco, Texas,

United States of America

Abstract

A MEDFLY ERADICATION PROPOSAL FOR CENTRAL AMERICA.

A survey sponsored by US/AID revealed that in 1970 direct crop losses due to Mediterranean fruit fly Ceratitis capitata (Wiedemann) infestations throughout 10 774 km2 (2 .7 m illion acres) in Costa Rica, Nicaragua and Panama approximated US$2.4 m illion . Potential annual losses would reach US$6.8 m illion were the m edfly to spread throughout presently uninfested Central Am erica. The survey team members estimated that

a 6-year eradication programme involving sterile flies, malathion mixed with protein bait, or malathion alone would cost US$30.8, US$25.7 or US$21.8 m illion , respectively. The subsequent revision o f these estimates by agricultural o ffic ia ls o f the OIRSA member countries resulted in a 5-year programme involving both malathion and sterile m edflies at a cost o f US$20.5 m illion . The financing would be provided by contributions from the governments o f the USA, the five Central American countries, Panama, M exico and the United Kingdom that would be deposited in CABEI to cover the operational costs. This sum would be repaid to

CABEI within 10 years and would constitute the nucleus o f an emergency fund to combat plant and animal diseases or pests within the OIRSA region. Additional monetary and/or technical support would be requested o f UNDP, IAEA, the University o f California and the Interamerican Institute o f Agricultural Sciences. Intensive

trapping for medflies within OIRSA countries that are ostensibly free o f this pest and in Belice should be a prerequisite to an active eradication programme. Supplementary information concerning m edfly ecology and methods o f marking and aerial release is needed.

One of the w orld 's most notorious fruit pests, the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), made its first appearance in Central Am erica near San José, Costa Rica, in 1955. Initial attempts to eradicate the medfly from the locally infested areas with insecticides were abandoned after the insect became generally established throughout the coffee-producing regions of the central highland plateau. Instead, the newly-created Organismo Internacional Regional de Sanidad Agropecuaria (OIRSA) presently undertook the responsibility of preventing the spread of the medfly to other Central Am erican countries. OIRSA, an international regional organization funded by annual contributions from its member countries, is concerned with the control or eradication of plant and animal pests and diseases that threaten

Liberal references have been made to Field Report 21, Economic Survey o f the Mediterranean Fruit Fly in Central Am erica, US Dept, o f Agriculture, in co-operation with US Agency for International Development,

1972, and Informe III Reunion Extraordinaria de Jefes de Sanidad y Cuarantena Vegetal, 15-18 de Mayo de 1973, Organismo Internacional Regional de Sanidad Agropecuaria.

159

160 RHODE

the agricultural economy of the five Central Am erican countries, Mexico and Panama. Nevertheless, despite regulatory and quarantine measures instituted by OIRSA to halt the medfly advance, the pest was detected in the Carazo region of Central N icaragua in 1961 and in Western Panama in 1963.

In an effort to develop non-insecticidal methods of reducing native medfly populations, OIRSA, with assistance provided by the United States and the Interamerican Institute of Agricultural Sciences (HAS), initiated a laboratory-rearing programme in 1958 for the production of medfly parasites and, concurrently, began investigations of medfly sterilization with gamma irradiation.

Also, in 1964, a pilot test involving the release of 1 million sterile medflies per week over a 1-square mile area on the peninsula of Puntarenas, Costa Rica, was carried out under a joint US/AID-OIRSA agreement. The results were sufficiently encouraging so that OIRSA, with United Nation's Development Program m e (UNDP) support, entered into a co-operative programme in 1965. with the International Atomic Energy Agency (IAEA) to determine the feasibility of eradicating the medfly from Central Am erica by means of the sterile insect release method. In an experiment conducted from September 1968 to May 1969, approximately 40 million sterile medflies were released by a ir each week over a 48-km2 coffee and citrus area in Nicaragua. Results of this test demonstrated that average deposition of viable medfly eggs, la rva l infestations in coffee fruits and recoveries of pupae from mandarin oranges w ereatleast 90.0% less in the release area than in the two checks [ 1 ] .

At the conclusion of the joint U N D P -O IR SA -IA E A co-operative program m e, a conference was held in 1970 at San José, Costa Rica, to assess the results of the sterile fly release experiment in Nicaragua and to discuss a course of further action to rid Central Am erica of this pest.In addition to officials of the foregoing organizations, other delegates represented US/AID, USDA, US Department of State, US Atomic Energy Commission, US A ir Force and the M inistries of Agriculture of each of the five Centred Am erican countries, Mexico and Panama. It was proposed and agreed that before considering a medfly eradication programme, US/AID would sponsor a study to determine ( 1 ) the economic losses sustained by the countries presently infested with the medfly, (2 ) the potential damages if the fly were to spread into previously non-infested countries and (3) to estimate the cost of eradicating the medfly from Costa Rica, Nicaragua and Panama.

Consequently, during 1971-72, a four-man team of specialists in entomology, tropical horticulture, agricultural marketing, and agricultural economics made an assessment of the medfly situation in Central Am erica. The team at that time considered that self-sustaining medfly populations were present throughout 1 672 km 2 in Nicaragua, 7 000 km2 in Costa Rica, and 2 102 km 2 in Panama, representing a total area of 10 774 km2 (F ig. 1).

Medfly infestations in these countries are generally found in developed highland areas cultivated to coffee and citrus and in sm all towns and settlements along the Pacific coastal plain where tropical almond (Term inalia catappa) and mixed fruit plantings occur.

Citrus is the only commercial host fruit crop — except coffee — grown on an economic scale. Coffee is a favoured host fruit of the fly and, even though this crop sustains the m ajor medfly infestations in Central Am erica, losses in coffee bean production were estimated to be only about 1%. Of the

APPENDIX I

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161

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^ Ш т Ъ П Ж —̂ 4 — Казa y a , 6ага?«Г'~^-

E lo C h ir iq u l V i e j o ,B oquete , liualaca^ \r ^ ч, ^Hor c o n c it e s , ' D avid Q * / 3 v-s 4 j>Viaí,a ///,>_ '<x \ '̂3v3>.

FIG. 1. Areas with a self-sustaining population o f Mediterranean fruit fly (Ceratitis capitata).

162 RHODE

citrus varieties, sweet orange and mandarines are the most heavily attacked. Medfly losses to fruit production in the infested Central Am erican countries were estimated to be about 28% for sweet oranges, 50% or more for mandarines, 24% for grapefruit and 2% for other susceptible fruits.

Applying these estimates of susceptible crop losses to the estimated value of fruit production in the current medfly area, the value of losses due to this insect in 1970 was about US $2.4 million. Should the medfly spread to a ll areas of Central Am erica, the same loss rates would cause a potential annual damage of US $ 6 . 8 million. W ere the medfly to invade Belice and Mexico, the citrus industries of these countries would suffer annual losses of US $1 million and US $5 million, respectively. Potential damages to the US fruit industry would be much greater. At one-half the damage rates observed in Central Am erica, medfly losses to the US citrus industry would approximate US $85 million annually. Because of the susceptibility of deciduous fruits to medfly attack, losses could amount to US $200 million annually, a sum which represents a third of the total value of production.

In their report, the medfly team emphasized the importance of establishing and enforcing strict quarantine m easures to prevent the medfly from being carried into areas where it is not established or where eradication is still incomplete. Internal quarantine operations within each country would entail the efficient control of terrestrial, aerial and maritime traffic at designated check points and at international boundary crossings. Even though a medfly eradication attempt is not undertaken in Central Am erica, a quarantine programme would still be necessary to retard the advance of the fly into new areas. Furthermore, upon completion of the Pan American highway, linking Panama with Colombia, vehicular traffic w ill provide the possibility for more rapid movement of the medfly and other exotic pests and diseases of agricultural importance between South and Central Am erica. The team recommended that quarantine stations be established in northern Nicaragua on the West Coast and Pan Am erican highways to control traffic moving into Honduras and E l Salvador. It was estimated that operational costs of the two new stations would amount to about US $269 000 for a 4-year period.

A thorough and continuous trapping programme throughout Central Am erica was also considered a necessary prerequisite to any programme or activity to control or eradicate the medfly. In the opinion of the team, a survey trapping programme should be conducted whether or not eradication of the medfly is attempted. Such an effort, utilizing triangular carton traps with Trim edlure incorporated in the adhesive material, would require external financing in the amount of about US $2.4 million. It is advisable that the survey programme be in operation at least 1 year before any control or eradication attempt.

The economic survey team judged that because of rugged terrain and associated adverse weather conditions, 3 740 km 2 of the total infested area of 10 774 km 2 could not be adequately treated by conventional airplanes — neither with insecticides nor sterile flies — and that the ground application of malathion bait sprays would be needed. Because of the broad scope of a programme to eradicate the medfly from Central Am erica, a 6 -year multistage plan of.operations was proposed which provides for 1 year of preparation devoted to advance trapping, construction, procurement of supplies, e tc ., followed by 4 years of m ajor eradication effort during which

APPENDIX I 163

one-fourth of the total infested area would be treated each year and, finally,1 year of final "m op-up".

Three alternate methods of eradicating the medfly were proposed: the use of malathion alone applied by air at 2 fl oz/acre, malathion at 2 fl oz/acre mixed with protein bait at a 1:4 ratio and the release of sterile flies. Although ultra-low-volum e (U LV ) malathion applications alone have not yet been proven completely effective against the medfly, it is known to cause a quick knock­down of flies [ 2 ] .

The C-123 multiengined jet-assisted airplane was considered the most practical type for la rge -sca le spray operations. Cities and towns lying within the air-treatable areas would receive coverages of malathion alone. Chemical treatments would consist of eight weekly spray applications for each of the insecticide program m es and would commence at the end of the wet period in November.

Marked medflies sterilized with 9 krad of gamma radiation would be released from DC-3 airplanes at the rate of 400 000 per km2 per week.A laboratory-rearing facility capable of producing 500 million flies per week would be centrally located at San José, Costa Rica. Sterile -fly releases would begin during the period of low w ild -fly population densities in September.

Because of potentially bad weather conditions and areas that may be missed in the application of the alternate methods of medfly eradication, some retreatment would undoubtedly be required. These costs were estimated at 5% of the total treatment cost for the current year of treatment and 1 0 % for the following year for each type of eradication programme.

An intensive medfly-monitoring programme which would provide accurate and up-to-date information on sterile and wild fly density and distribution in the work areas is an essential element in an eradication project. It is estimated that the yearly cost of monitoring 10 sticky traps per km2 per week over 1 000 km2 would be about US $ 1.2 million.

Total costs of each of the proposed eradication techniques, used alone, including costs of retreatment and a monitoring program m e, were estimated by the economic survey team at US $21.8 million using U L V malathion,US $25.7 million using malathion-bait spray, and US $30.8 million employing sterile fly re leases.

In early 1973, OIRSA became increasingly alarmed with the consequences attendant upon the evacuation and displacement of a large portion of the population of Managua, Nicaragua, ravaged by earthquake in Decem ber 1972. To resettle in outlying areas, many of the homeless circumvented the internal medfly quarantine station situated on the Pan Am erican highway, 22 km north of Managua, by dispersing along secondary roads and trails. Sporadic out­breaks of the medfly in northern towns previously freed of this pest indicated the probability that infested fruits from the m ajor citrus producing region in central N icaragua were being received in these areas to meet the demands of increased local consumption.

At an extraordinary reunion of the Ministers of Agriculture of the OIRSA member countries held in February 1973, OIRSA urged the immediate reinforcing of existing quarantine, trapping and control program m es to curtail the northward spread of the medfly. Considering the vulnerability of E l Salvador and Honduras to invasion because of their proximity to medfly infestations in Nicaragua, OIRSA recommended a study be made of the AID Economic Survey Report to develop a technical-economic strategy to rid the

164 RHODE

currently infested countries of this pest. Subsequently, in May 1973, officials of Vegetable Health and Quarantine Departments from the OIRSA countries met with members of OIRSA, US/AID (ROCAP), USDA, the economic survey team and the Central American Bank for Economic Integration (CABEI) to discuss strategy, costs and a possible manner of financing an eradication programme.

From this conference evolved an integrated programme of up to 5 years duration which would utilize insecticides and sterile insects to achieve eradication through the following sequential approach:

(1) 6 ULV-m alathion sprays at 1-week intervals(2 ) 2 malathion-protein bait sprays at 2 -week intervals(3) 3 months of weekly sterile -fly releases at a rate calculated to

maintain a minimal sterile -to -w ild -fly ratio of 1 0 0 : 1 .

The delegates considered the ground application of insecticides to the area of 3 740 km2 proposed by the medfly survey team to be economically untenable and projected the use of malathion-bait sprays applied by heli­copter as a means of reducing the estimated costs. Other revisions of item costs presented in the Economic Survey Report resulted in an eradication programme with an overall cost of about US $20.5 million composed of the following operational expenses:

(1) Survey, trapping and quarantine..............................US$1 859 826(2 ) Supervision .................................................................. 2 029 157(3) Insecticide applications.............................................. 7 989 442(4) Sterile fly production and re le a se ............................. 6 734 200(5) Adm in istration ............................................................ .......... 1 861 263

Total US$20 473 8 8 8

A s some possible means of obtaining the necessary funding for an eradication project advanced at the May 1973 conference, it was proposed that each OIRSA member country increase its own normal national quarantine service support by 1 0 0 % for the first year of the programme and by an additional 50% for the second year. Individual country support would continue at this level until 2 years after the medfly is declared eradicated in Central Am erica. In addition, each OIRSA country would contribute a determined amount to a fund established in CABEI for financing the initial phase of the eradication programme and all countries would become current in payment of their annual quotas. A grant contribution would be requested of the Mexican Government to be used for operating costs. The amount of this loan would be deposited in CABEI.

A loan would be requested of the United States Government through US/AID (ROCAP) to be deposited in CABEI as part of a "Medfly Eradication Fund" used to finance equipment, insecticides, local salaries, and other costs. This fund would be administered by CABEI under the technical direction of an O IRSA-USDA-IAEA-IIAS Technical Advisory Committee to be established to guide this joint effort.

Portions of the US contribution would be made available to the Central Am erican countries for graduate training of national technicians in entomology and short-course training of engineer agronomists and lower technician

APPENDIX I 165

levels in methods of trapping, quarantine, spraying, insect identification, etc. Also to be paid from the US loan are the salaries and associated expenses for 6 USDA advisors for a 5 -year period to assist in various aspects of the program m e as well as the costs associated with aeria l spraying carried out by the US A ir Force in the event that assistance in the form of up to three C-123 aircraft with ULV-dispensing equipment becomes available.

The UNDP would be requested to provide monetary assistance for an expanded rearing facility and research and technical assistance support through IAEA.

Other research assistance would be requested of US/AID-Technical Assistance Board/University of California Pest Management Research Project to work with IAEA and IIAS on insect radiation and release, research related to aeria l and ground spray systems, collecting and processing of trap data and the provision of technical training program m es required by field and other support personnel.

A request would be made of IIAS to provide research assistance on a study to determine the effects of the medfly on tropical crops and to make an analysis of the benefits to be derived by the Central American countries through crop diversification and , also, to help in formulating a strategy including location, crops, costs, etc. for the development of new crop production with special emphasis on sm all and medium farm operations that could be im ple­mented as soon as possible after the medfly becomes eliminated in Nicaragua, Costa Rica, and Panama.

The British Foreign Assistance Agency would be requested to augment its financial support to Belice for increased quarantine, trapping and related program m es to prevent medfly introduction. In addition, the British Government would be asked for a contribution to be deposited with other funds in CABEI for costs associated with the eradication programme in Central Am erica.

Monies deposited in CABEI for use in defraying the operational expenses of the eradication programme would be repaid to CABEI by the OIRSA member countries in annual quotas within a 1 0 -year period and would serve as the nucleus of a revolving "Emergency Pest Eradication Loan Fund". This fund would be available under conditions determined by the OIRSA directors for the control or eradication of pests or for other problems considered emergency situations by OIRSA.

The actual dollar values of contributions requested of the various governments and international agencies w ill be considered following approval of the financing plans by governments of the OIRSA member countries.

Before commencing an active eradication attempt in Central Am erica, it would seem advisable that intensive trapping surveys be conducted throughout the OIRSA region and Belice to determine if the medfly has encroached upon territories previously considered free of this insect.It is not improbable that the scope of the proposed eradication effort would be influenced by the number and size of any infestations discovered in the countries north of N icaragua. More detailed information is also needed concerning medfly distribution within each of the currently infested countries, particularly along the Atlantic littorals and in mountainous areas of restricted accessibility. Remote-sensing techniques employing colour in fra-red aeria l photography would provide a rapid and relatively inexpensive means of detecting susceptible host fruit plantings or, alternatively, of eliminating the

166 RHODE

need for extensive ground reconnaissance of undeveloped or agriculturally unsuitable regions.

Additional knowledge of wild-medfly life cycles, particularly the length of pupal development in different climatic environments, and the correlation of trap catches to native fly population densities, would be beneficial.Insect marking is a crucial element in sterile-insect release program m es. Existing methods for marking the adult insect, using fluorescent powders applied to the pupae, must be improved upon or practical alternative means found which would ensure virtually 1 0 0 % identification of captured laboratory- reared medflies. It would also be desirable beforehand to compare methods of releasing sterile flies by air under conditions existing in the proposed work environment to determine whether medflies released in containers or discharged unconfined into the air stream constitutes the most effective and practical method. Electronic guidance systems to direct airplanes accurately along flight lines over forested areas must also be evaluated in advance under flying conditions present in Central Am erica.

Even though the technological basis for suppressing wild medfly popu­lations with chemicals and sterile insects has been established, the uneven terrain and variable weather patterns of Central Am erica, in association with the general lack of communications, inadequate roads and landing fields in outlying areas, could present formidable barrie rs to an eradication effort.

Problem s with logistics could be expected because of the time required to import supplies and equipment from markets outside the Central American region and the administrative delays involved in transporting material across international boundaries.

A tentative eradication strategy, advanced at the May 1973 conference, would exert a closing action on the medfly-infested region of Central Am erica by the initial and simultaneous treatment of Nicaragua and Panama. However, in addition to the increased operational burdens created by a divided campaign, any eradication attempt in Panama would involve areas of southern Costa Rica because of medfly infestations in the border regions. Among other factors, a successful eradication enterprise would include the precise co-ordination of various specialized activities. It is unlikely that an untested task force would have the proficiency needed to overcome the obstacles imposed by widely separated and difficult work environments located in three different countries. OIRSA, therefore, may wish to consider concentrating the initial effort in Nicaragua rather than risk the possibility of the newborn programme becoming overwhelmed at the outset by a multi­tude of unresolved problem s. Because of the nature of its widely dispersed areas with medfly infestations, Nicaragua, in itself, would provide an uncompromising proving ground, under working conditions sim ilar to those which would be faced with confidence and expertise at a later time in Costa Rica and Panama.

R E F E R E N C E S

[ 1 ] RHODE, R .H ., SIMON, J . , PERDOMO, A . , GUTIERREZ, J ., DOWLING, C .F . Jr., LINDQUIST, D .A . , Application o f the sterile-insect release technique in Mediterranean fruit fly suppression, J. Econ. Entomol. 64 3 (1971) 708.

[2 ] RHODE, R .H ., PERDOMO, A . , DAXL, R ., GUTIERREZ, J . , Control o f Mediterranean fruit flies in shade-

grown co ffee with u ltra-low-volum e aerial insecticide applications, J. Econ. Entomol. 65 6 (1972) 1749.

APPENDIX II

REPORT OF THE Illrd MEETING OF THE INTERNATIONAL ORGANIZATION OF

BIOLOGICAL CONTROL - WEST PALAEARCTIC REGION SECTION (IOBC/WPRS)

WORKING GROUP ON GENETIC CONTROL OF THE MEDITERRANEAN FRUIT F LY

(IAEA, Vienna, 17 November 1973)

I. Present: (A ) IOBC/WPRS Working Group

1. Mellado (Spain, Co-ordinator)2. Cavalloro ( C . E . C . )3. Cirio (Italy)4. Serghiou (Cyprus)5. Wakid (Egypt)

(B ) IOBC Members

1. Simón (Peru)2. Turica (Argentina)

. (C) Observers

1. Cavin (USDA, APHIS representing the USAID Pest Management Project)

2. Chambers (USDA, ARS)3. H arris (USDA, ARS)4. Moore (FAO/IAEA, Rapporteur)

II. Contents: Report

Annex I of Appendix II: List of laboratories involved inMediterranean fruit fly activity.

Annex II of Appendix II: Addresses of participants inIOBC/WPRS medfly working group.

167

168 APPENDIX II

1. The IOBC/WPRS Working Group on Genetic Controlofthe Medfly during its 3rd meeting (IAEA, Vienna, 17 November 1973), recognized that around the Mediterranean basin there were 11 laboratories involved in research activities on medfly and/or m ass production of the insect for its suppression in their respective countries.Mass production of medfly is also being carried out at the IAEA laboratory at Seibersdorf.The laboratories involved are listed in Annex I.

2. The expertise accumulated in these various laboratories now has reached the point where upscaling medfly production is no problem, given the proper incentive and support. The Working Group, including the others present at the meeting (addresses listed in Annex II), felt that any one of these laboratories cannot on its own realistically undertake a large-scale project of Mediterranean fruit fly control by the sterile-insect technique. However, the experience of these laboratories shows that eradication of the medfly by this technique under suitable conditions and with adequate support is possible.

3. Having surveyed conditions in the various Mediterranean areas where the medfly is endemic, it was concluded that an eradication campaign should be carried out through a concerted effort, provided this be concentratedin a single appropriate area. The co-ordination for such a collaborative effort would have to come from an international organization and the group agreed this could best be done by the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture. The IOBC/WPRS Group, which originated this collaborative concept, should play an active role in an advisory capacity by providing:

Advice on general guidelines of the campaign; »Advice on implementation of the programme and selection of specialists; Expertise on location as required;Periodical meeting to review the progress of the programme and develop future activities.

4. The review of the medfly situation in the Mediterranean region shows that it is technically and economically feasible to achieve eradication of the medfly in Cyprus. Geographically and environmentally, Cyprus has allthe conditions required to make such a project successful1.

5. The group understands that the Cyprus Government is interested in such a project and would be ready to approach an organization such as the W orld Bank, the European Communities, etc. for the financial support needed. The group would strongly endorse and support such a request from the Cyprus Government.

1 This report reflects the situation before 1974; the project has since been temporarily suspended.

APPENDIX II 169

6 . A s regards implementation, the group is ready to contribute the exper­tise of all its members. Since this eradication campaign hinges on massive supplies of sterile medflies, the group suggests that the Cyprus Government makes a major effort to increase the present level of its medfly production by expanding the facility of its Agricultural Research Institute.

7. The group recognizes that for eradication even with production at m axi­mum capacity, the Cyprus facility could not meet the requirements in numbers of sterile medflies. Therefore, the group recommends that the necessary supplies of sterile medflies be obtained from the other laboratories in the Mediterranean area. Principal reliance should be on facilities logisti- cally appropriate; the other facilities would provide emergency sourcesand genetic heterogeneity.

8 . The group also recommends that Cyprus creates the conditions needed for successful eradication such as quarantine, appropriate bait spraying and cultural practices, farm er participation and Government involvement as required.

9. Success in this intérnationally co-ordinated campaign of eradication of the medfly in Cyprus would act as a catalyst for other programmes requiring international co-operation. Likewise, this would stimulate support of ongoing or proposed projects. Both these aspects would be major benefits of this proposal.

170 APPENDIX II

ANNEX I OF APPENDIX II

LABORATORIES INVOLVED IN M ED FLY ACTIVITIES

1. INIA, Madrid, Spain

2. Universitá degli Studi, Istituto di Entomología A graria , Palerm o, Italy.

3. Laboratorio Applicazioni in Agricoltura, CNEN, Casaccia, 00060 Rome, Italy

4. Centro Regionale Anti-Insetti, Cagliari, Italy

5. Centro Studi Provinciale Antimalar ico, Latina, Italy

6 . Agricultural Research Institute, N icosia, Cyprus

7. European Communities: Euratom, Common Nuclear Center,21020 Ispra, Italy

8 . Radiobiology Department, Atomic Energy Authority, Cairo, Egypt

9. Ministry of Agriculture, Giza, Egypt

10. Universitá degli Studi, Istituto di Entomologia A graria , Portici,Napoli, Italy

11. Biological Control Institute, Citrus Marketing Board of Israel,Rehovot, Israel

12. IAEA Entomology Laboratory, IAEA, Vienna, Austria.

APPENDIX И 171

ANNEX II OF APPENDIX II

ADDRESSES OF PARTICIPANTS IN IOBC/WPRS M ED FLY WORKING GROUP

1. Dr. R. CavalloroCommission of the European Communities,Ispra, Italy

2. Dr. G. CavinUSDA, Federal Center Big. ,Hyattsville, Maryland 20705, USA

3. Dr. D . L . ChambersInsect Attractants, Behavior and Basic Biology Research Laboratory, USDA, ARS,P .O. Box 14565,Gainesville, F lorida 32601, USA

4. Dr. U. CirioCentro di Studi Nucleari della Casaccia,Comitato Nazionale per l'Energia Nucleare,Casella Postale N. 2400,00100 Rome, Italy

5. Dr. E.J. H arrisUSDA, ARS, Western Region Southern California-Hawaii A rea, Hawaiian Fruit F lies Lab. ,P . O . Box 2280,Honolulu, Hawaii 96804, USA

6 . D r. L. MelladoInstituto Nacional de Investigaciones A grarias,Avda. Puerta de H ierro,Madrid 3, Spain

7. Dr. I. MooreJoint FAO/IAEA Division of Atomic Energy in Food and Agriculture, Kârntner Ring 11,1011 Vienna, Austria

8 . Dr. C. Serghiou Agricultural Research Institute,M inistry of Agriculture and Natural Resources,Nicosia, Cyprus

9. Dr. J.E. Simón FCentro Regional de Investigación Agraria ,La Molina, Apartado 2 791,Lim a, Peru

1 0 .

1 1 .

172

Dr. A. TuricaInstituto Nacional de Technología Agropecuaria, Centro de Investigaciones en Ciencias Agronómicas, С. C. 25, Castelar,Bueonos A ires, Argentina

Dr. A. M. WakidAtomic Energy Establishment,Cairo, A rab Republic of Egypt

APPENDIX II

LIST OF PARTICIPANTS

BATEM AN, M. A.

BO LLER , E . F .

BRNETIC, D.

BUSH, G. L.

CAVALLORO, R.

CAVIN, G.

CHAMBERS, D. L.

CIRIO, U.

ECONOMOPOULOS,

C . S . I . R . O . ,School of Biological Sciences,University of Sydney,Sydney, N. S.W. 2006,Australia

Swiss Federal Research Station for Arboriculture,Viticulture and Horticulture,

Wâdenswil, Switzerland

Institut za Jadranske Kulture i M elioraciju Krsa,

Split, Yugoslavia

Dept, of Zoology,University of Texas,Austin, TX 78712,United States of Am erica

Commission of the European Communities, Ispra, Italy

USDA, Federal Center Big. ,Hyattsville, MD 20705,United States of Am erica

Insect Attractants,Behavior and Basic Biology Research Lab. , USDA, ARS,P .O. Box 14565,Gainesville, F L 32601 United States of Am erica

Laboratorio Applicazioni in Agricolture, Comitato Nazionale per l'Energia Nucleare, Casella Postale N. 2400,00100 Rome, Italy

.P . Nuclear Research Center "Dem ocritos",Aghia Paraskevi,Attiki, Greece

173

174 LIST O F PAR TIC IPAN TS

ENKERLIN S, D.

FISCHER-COLBRIE, P.

G O N ZALEZ, R.

HAISCH, A.

HARRIS, E.J.

M ELLADO, L.

REJESUS, R.S.

RUSS, K.

SERGHIOU, C.

SIMÓN F, J. E.

THEUNISSEN, J.

Instituto Tecnológico y de Estudios Superiores de Monterrey,

Monterrey, N. L . , Mexico

Bundesanstalt für Pflanzenschutz, Trunnerstrasse 5,1020 Vienna, Austria

Plant Production and Protection Division, FAO,Rome, Italy

Bayerische Landesanstalt für Bodenkultur und Pflanzenbau,

Postfach,8 München 38,Federal Republic of Germany

Hawaiian Fruit F lies Lab. ,USDA, ARS,P .O. Box 2280,Honolulu, HI 96804,United States of Am erica

Instituto Nacional deInvestigaciones Agrarias,

Avda. de Puerta de H ierro,Madrid 3, Spain

College of Agriculture,University of The Philippines at

Los Baños,College, Laguna, Philippines

Bundesanstalt für Pflanzenschutz, Trunnerstrasse 5,1020 Vienna, Austria

Agricultural Research Institute,Ministry of Agriculture and

Natural Resources,Nicosia, Cyprus

Dirección General de Investigaciones Agropecuarias,

La Molina, Apartado 2791,Lim a, Peru

Institute for Phytopathological Research, Binnenhaven 12,Wageningen, The Netherlands

LIST OF PAR TIC IPAN TS 175

TSITSIPIS, J.

TURICA, A.

V A LLO , V.

W AKID, A. M.

ZERVAS, G.

ZIM M ERM ANN, E.

PR O K O PY , R.

Nuclear Research Center Aghia Paraskevi,Attiki, Greece

Democritos

Instituto Nacional de Technología Agropecuaria,

Centro de Investigaciones en Ciencias Agronómicas,

С. C. 25, Castelar,Buenos A ires, Argentina

Institute of Experimental Phytopathology and Entomology,

Ivanka pri Dunaji,Bratislava, Czechoslovakia

Radiobiology Dept. Atomic Energy Establishment,

Cairo, Egypt

Nuclear Research Center Aghia Paraskevi,Attiki, Greece

'Democritos"

Bundesanstalt fur Pflanzenschutz, Trunnerstrasse 5,1020 Vienna, Austria

Nuclear Research Center Aghia Paraskevi,Attiki, Greece

Democritos

International Atomic Energy Agency

LINDQUIST, D. A. SIGURBJORNSSON, B.

Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture

BUTT, B. A.NADEL, D. J. TISCHLINGER, Anne W EHRSTEIN, A.

Division of Research and Laboratories

MO UR AD, A. IAEA Fellow at the Seibersdorf Laboratory

SCIENTIFIC SECRETARY

MOORE, I. Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture

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U .S .S .R . M e z h d u n a ro d n a y a K n ig a , S m o le n s k a y a -S e n n a y a 3 2 -3 4 , M o s c o w G -2 0 0 Y U G O S L A V IA Ju g o s lo ven ska K n jig a , T e ra z ije 2 7 , Y U - 1 1 0 0 0 B e lg ra d e

j r | Orders from countries where sales agents have not yet been appointed and requests for information should be addressed directly to:

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IN T E R N A T IO N A L A T O M IC E N E R G Y A G E N C Y V IE N N A , 1975

PR IC E : U S$10 .00Austrian Schillings 190,— <£5.00; F.Fr. 45; D M 27 ,-)

SU B JEC T G ROUP: I Life Sciences/Entomology