J. Asia-Pacific EntomoI. 6(2): 207-212 (2003)www.entomology.or.kr

CHEMICAL CONTROL

Efficacy of Probe Traps Supplemented with an Attractant and Repellent for theControl of Rhizopertha dominicaWaseem Akram*, Zia Ullah Malik!, Jin-Bog Koh2 and Jong-Jin Lee

Faculty of Biological Resources Science, Chonbuk National University, Chonju, Korea

JDepartment of Agricultural Entomology, University of Agriculture, Faisalabad, Pakistan2Department of Life Science, Silla University, Busan, Korea

Abstract Rhizopertha dominica is a serious pest ofstored commodities. The population shows its peakduring the monsoon season. The use of chemicalshas resulted in resistance. Therefore, some substi­tutes need to be identified; the probe traps are oneof such techniques. The laboratory-reared 50,000adults of both sexes were used for present investi­gation. The response of this insect was tested againstempty probe traps and those filled with tobacco andneem dried leaves and mustard oil as repellents andattractant, respectively. It has been observed thatprobe traps have the ability to provide aggregatingplaces for Rhizopertha dominica, while the perfor­mance of these traps could further be enhanced withtobacco leaves, as these helped to trap more indi­viduals after 72 hr.

Key words Rhizopertha dominica, probe traps, at­tractant, repellents, control

Introduction

Wheat is the staple food and is most commonly usedin Pakistan. It is sown on 8.1 million hectares. Totalrequirement ofwheat during 1996-97 was 39,760,000tons with a total production of 16.4 million tons inPakistan (Anonymous, 1997a). Wheat is not muchattacked by insect pests in the field as in thestorehouses. As such 45 species of insects have beenrecorded which feed on grains and its products,among these most of the damage is done by khaprabeetle, granary weevil, rice weevil, rice moth, flourbeetles and lesser grain borer (Ahmed, 1980). Avesi(1983) reported that 2-6% food is lost due to theattack of insect pests mainly the coleopterans andlesser grain borer (Rhizopertha dominica), is one of

*Corresponding author.E-mail: apwaseem18@yahoo.comTel: +82-63-270-2528

(Received May 22, 2003; Accepted August 6, 2003)

them. Both larvae and adults damage kernel, withtheir hard mandibles and eat at first the flossy materialand then whole grains.

The continuous use of pesticide has created theproblem of resistance in insects. Therefore, the needis of non-chemical approach. Many different typesof traps are being used for monitoring the insectactivity in grain storage. These include pheromonetraps, light traps, attractant baited traps. Athanassiouand Buchelos (2001) tested the probe traps againstthe stored grain insects and reported better captures.Research using certain plants and plant products hasbeen on way with varied success. Hagstrum et al.(1984) monitored sticky traps correctly predictedwhether R. dominica and Cryptolestes ferrugineuswould be found in grain samples in 85.8% and 78.6%of the bins. Obeng-Ofori (1995) evaluated plant oilsfor their ability to suppress populations of C. pusillusand R. dominica in maize and sorghum grain atdifferent dosages in the laboratory. Weaver et al.(1995) tested leaves of two highly aromatic plants,Artemisia tridentata and Monarda fistulosa, thatinhibited oviposition of Zabrotes subfasciatus on beansat a concentration less than 1% w/w. Azadirachtaindica, a member of the Meliaceae (mahogany)family, is referred to in the past by the botanicalnames, Melia indica and M azadirachta, is perhapssometimes confused with a related species, Mazedarach (chinaberry) (Anonymous, 1997b). In ruralIndia dried neem leaves are mixed with grains meantfor storage. Mixing of neem leave (2-5%) with rice,wheat and other grains is practiced in some parts ofIndia and Pakistan even today (Anonymous, 1997b).Early observations that neem leaves were not attackedby swarming locusts were also confirmed in labo­ratory studies and attributed to neem's anti- feedantactivity against locusts, thus neem which does notkill pests but affects their behaviour and physiology(Anonymous, 1997a). In a diagnostic survey, it isreported that food grains are mostly stored in gunnybags in which farmers sometimes mix dried neemleaves or tobacco leaves. Those who store wheat in

208 J. Asia-Pacific Entomol. Vol. 6 (2003)

mud bins, rub fresh neem or tobacco leaves on theinside walls of the bins. 20 % of water extract ofneem leaves can block the penetration of insects intotreated bags for at least 6 months during storage(Baloch, 1997). Nautiyal (2002) reported that forlong-term storage the containers should be sealed withmud after the addition of ashes, ground pepper, driedneem and tobacco leaves or other local herbs to controlstorage pests. As azadiracthin and all other biologicallyactive compounds are present in neem (Jacobson,1989; Koul, 1990; Schmutterer, 1990), although it hasbeen reported that other tissues of neem known tocontain chemicals used in suppressing the populationsof stored insect are present at lower levels in barks,leaves and heartwood (Ascher, 1993). But leaves, barkand roots and seeds of neem also elaborate as manyas sixty tetranortiterpinoids related to azadiracthin, allin minute quantities, and all these "neem bitters"contribute to the pesticidal activity. Jacobson (1983)identified plants as particularly promising commercialsources of natural insecticides, insect repellents, orattractants. These are sweetflag (Acorus calamus), bigsagebrush (A. tridentata), neem (A. indica), tobaccoleaves (Nicotiana sp.), Heliopsis (Heliopsis longipes),mamey apple (Mamea americana), sweet basil(Ocimum basilicum), and Mexican marigold (Tagetesminuta). Of the seven plants discussed, the neem andtobacco tree seems to have the greatest potential asa commercial crop. Sanewe and Young (1999)reported tobacco (N tabaccum) and chinaberry tree/Persian lilac/ umbrella tree (M azedarach) leaves areeffective as grain repellents and for nymphs andhiding larvae. Keeler (1982) reported that chinaberryand tobacco as toxic plants that can be used for thecontrol of insects both under field and storeconditions. Golob and Webley (1980) and Saxenaet al. (1989) reported that chinaberry and tobaccoleaves can reduce attractiveness as a protectant in foodgrain against R. dominica. The azadiracthin contenthas also been analyzed in relation to developmentand growing conditions of the trees (Gruber, 1991).Plant extracts from different ecotypes give rise to avariation in the anti-feedant activity (Singh, 1987).Stoll (1988) suggested using powder ofdried chinaberryleaves and seeds in stored grain. In addition, barkshave been used as powder against bruchid beanweevils.

Although the seeds and leaves have been used asa traditional insecticide for centuries, modem interestin neem as an insecticide dates to the work of Pradhanet al. (1962). Several other limonoids related toazadiracthin have antifeedant, growth-inhibitory, ormolt-disrupting properties in insects (Kubo and Klocke,1986), meanwhile salannins from the chinaberry arealso very effective in controlling insects (Kraus etal., 1987). Hashem et al. (1991) reported chinaberry

leaves and fruits extract are promising natural pest­icides causing morphological abnormalities as wellas physiological disturbances in insects; a preliminaryfield test in 1993/94 showed that chinaberry reducedthe levels of infestation of stalk borer (Assefa andFerdu, 1999).

Thus keeping in view the existing role of plantchemicals in suppressing populations of stored insectpests the present studies have been initiated with astep ahead of testing the leaves of these plants oroil in probe traps a device that is especially designedto sample the stored grain insect populations.

As the present project is designed for the first timeto record the population build up during the storageperiod in store houses and evaluate the efficacy ofnon-chemical measure using probe traps supplementedwith an attractant and repellents. Therefore the mainaim of the present studies is to measure at what leveland time the probe traps are more effective and doesthe supplementation with repellents or attractantimprove the efficacy of the probe traps.

Materials and Methods

Test insect

Rhizopertha dominica has been used as the test insect.Initial populations were collected from various farmhouses, godowns and store houses etc. Individuals forestablishment of a laboratory culture of 50,000 adultsof R. dominica were produced to test the efficacyof probe traps, a hole-filled tube like devicesapproximately 30 em long and 3 em in diameter,supplemented with an attractant and repellents instored wheat grains. Field population of about 500adults (t and -!f-) was released in 250ml bottlescontaining wheat flour and yeast at a ratio of 12:3tablespoons. The bottles were placed in an incubatorset at 30-32°C with 75% relative humidity. After 7days of reproduction the adults were transferred tosimilar bottles with the help of sieve, containing wheatflour and yeast in the same proportion as mentionedabove. However, the larvae and eggs were allowedto complete their life cycle in same bottles.

Experiment

Metallic bins with a capacity of about 800 kg werekept under sun for a day before they were filled with300 kg wheat grains. Wheat was dried to make itfree from R. dominica or any other stored productpest. Thereafter the efficacy of blank probe traps was

Efficacy of probe traps 209

60

Time intervalsat whichpopulation of Rhizopertha dominica trapped fromemptyprobetraps

Fig. 1. Population of Rhizopertha dominica trapped at dif­ferent time interval and population levels from empty probetraps.

10872

w--- - _

36

Populationlevels~300

600-It. 900

--v-~ 12009 1500

empty probe traps proved effective after 108 hoursin bins that contained 1,500 individuals. The numberof trapped individuals were comparatively higher i.e.71.67 per trap (Fig. 1). It was also observed that thenumber of individuals aggregating in empty trapsincreased with respect to time and regardless of thereleased population. These results thus formed thebasis of lateral trials, that is the use of attractant orrepellents to further investigate the efficiency of thesetraps, present studies are supported by Anonymous(2003a) who reported better traps with the probes.

Performance of probe traps with each of thealternate of Insecticide at 300, 600, 900, 1,200 and1,500 individuals was investigated. Dried leaves ofneem were filled in three probe traps and these wereplaced vertically in the metallic bins together withsix empty probe traps. Population trapped after 36,72 and 108 hr of release was recorded and it wasfound that after 36 hours interval on an average eachempty probe trap captured significant number 229.33individuals from 1,500 as against 30.00,59.67,90.67and 123.67 individuals from 300, 600, 900 and 1,200adults, respectively. As the time span increased (72and 108 hr) the population showed a decreasing trendand the individuals started moving out of empty trapsin bins containing 1,500 individuals. The populationdecrease ranged from 229.33 individuals to 186.33and 159.67 individuals after 36, 72 and 108 hr,respectively. It was interesting to note that in thepresence of neem leaves filled traps lower populations(300, 600, 900 and 1,200) tend to aggregate moreafter 72 hr in probe traps as compared to theindividuals entering the traps after 36 hr. However,

Statistical analysis

tested at five population levels, i.e. 300, 600, 900,1,200 and 1,500 adults in bins containing 300kg ofwheat with six traps/bin. The traps were placed atrandom and data was recorded after 36, 72, and 108hr with settlement time of 24 hr. After each obser­vation adults were counted, destroyed and positionof traps changed. Later the efficacy of probe trapssupplemented with dried leaves of neem, tobacco andmustard oil at same population levels mentionedabove was tested. A total of 27 probe traps were usedwith nine in each bin. Out of nine, three probe trapswere filled with dried leaves of either of the repellentor with an attractant and six were kept empty. Datawas collected after 36, 72 and 108 hr. The individualscollected in each trap were counted and destroyed.

Results and Discussion

Our results and field observations have shown thatR. dominica is active during the monsoon season whenthe temperature is between 35°C and RH 70%. Duringthis period maximum damage is caused by immatureand adults. However during colder months thepopulation tends to be lower and only the adults arevisible (Baloch, 1997). As most of the farm housesand retailers find it difficult and expensive to usechemicals for the control of stored insects. Thereforethe use of probe traps filled with attractant andrepellents has been developed for providing easy andquick control of stored insects with very low costat all levels of storage. Anonymous (2003) reportedprobe traps are very sensitive and can show infestationwell before it is economically threatening.

The results reveal that probe traps were effectiveonly at higher population levels after a given timespan. Our findings are exactly in agreement with theresults of Athanassiou and Buchelos (2001) whoreported that probe traps have better potentials to trapstored insects. Under present circumstances wherefive population levels (300, 600, 900, 1,200, and1,500) with three time periods (36, 72 and 108 hr)and six probe traps per metallic bin were selected,

The trapped insects from each metallic bin repre­senting one replication of a treatment were recordedafter given time period. One way analysis of variancewas used for selected columns at alpha 0.05 levels.Means at various time intervals were calculated,compared and graphically splined individually fordifferent time intervals as well as for the attractantand repellents using Microcal Origin 6.0 software.

210 J. Asia-Pacific Entomol. Vol. 6 (2003)

out ward trends tend to be higher after 108 hr (Fig.2). Present studies are in agreement with those ofJacobson (1989), Koul et al. (1990) and Schmutterer(1990) who reported that neem contains biologicallyactive compounds effective against insects. Thesestudies have further been supported by Anonymous(1997a) who reported neem which does not kill pestsbut affects their behaviour and physiology. Thereexists every possibility of using leaves in probe trapsbecause of certain chemicals that can effect the insectpopulation in general; this idea of generating theleaves of neem for present studies has been supportedby Stoll (1988) who suggested using powder of driedchinaberryleaves and seeds in storedgrain. Meanwhile,barks have also been used as powder against bruchidbean weevils.

Results from tobacco leaves (Fig. 3) yielded bestvalues and it was found that maximum and statisticallysignificant number of individuals 234.00 on anaverage from each of the six vertically held traps weretrapped at 1,500 populations after 72 hr. Efficiencyof tobacco leaves on the whole was found much betteras compared to neem leaves as the number ofindividuals trapped on all population levels werehigher and population trapped showed an increasingtrend of trapped individuals up to 72 hr possiblybecause of reduced growth and survival of manyinsects as has been reported (Glawe et al., 2003).

It was interesting to note that the population startedmoving out at a faster rate from the traps set in binscontaining 300 and 600 individuals after 108 hrhowever, the trend was increasing in bins where 900and 1,200 individuals were released. Present studies

are supported by the work of Golob and Webley(1980) and Saxena et al. (1989) who reported thatchinaberry and tobacco leaves can reduce attractivenessas a protectant in food grain against R. dominica.Although we don't find any reference directly relatedto present studies emphasizing the comparison ofneem and tobacco leaves in controlling the insects,but there exists a strong correlation of these biologicalactive plants in suppressing the population of insectsas has been supported by Pradhan et al. (1962),Jacobson (1983), Baloch (1997), Sanewe and Young(1999) and Nautiyal (2002).

In the final part of the project an attractant mustardoil (Fig. 4) was filled in three probe traps and thesewere placed vertically together with six empty probetraps in metallic bins. The results recorded reveal thatthe population trap compared with repellents wasmuch lower on over all basis. However, maximumpopulation (72.33 individuals/trap) was trapped at1,500 populations after 72 hr and it is different fromthe population trapped at 300, 600, 900 and 1,200levels being 9.67, 23.33, 33.67 and 64.33 individuals,respectively. It is further evident that populationaggregating after different time intervals and movingout wards did not show significant trend as comparedto neem and tobacco leaves. Present findings are inagreement with Obeng-Ofori (1995) who evaluatedplant oils for suppressing populations of R. dominica.Present results are also in accordance with Weaveret al. (1995) who teated leaves of two highly aromaticplants and was able to inhibit oviposition.

Comparison of population trapped after 36 hr fromprobe traps supplementedwith attractant and repellents

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Time intervals at which population of Rhizoperthadominica trapped fromneem leaves filled probe traps

Timeintervals atwhich population of Rhizopertha domimca trapped fromtobacco leaves filled probe traps

Fig. 2. Population of Rhizopertha dominica trapped at dif­ferent time interval and population levels from dried neemleaves filled probe traps.

Fig. 3. Population of Rhizopertha dominica trapped at dif­ferent time interval and population levels from dried tobaccoleaves filled probe traps.

Efficacy of probe traps 211

Time intervals at whichpopulation of Rhizopertha cJorrinica trappedfrommustard oil filled probe traps

250

400 600 800 1000 1200 1400 1600

Number ofAdults of Rhizopeltha dominiea released

10872

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--------.----.36

Popu!alionLevels~300

000• 900

-..---12OJ

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Fig. 4. Population of Rhizopertha dominica trapped at dif­ferent time interval and population levels from mustard oilfilled probe traps.

Fig. 6. Number of Adults of Rhizopertha dominica trappedafter 72 hr of release in probes traps supplemented withattractant or repellents.

300 600 900 1200 1500

Number ofAdults of Rhizopeltha dominiea released

300 600 900 1200 1500

Number ofAdults of Rhizopeltha dominiea released

Fig. 5. Number of Adults of Rhizopertha dominica trappedafter 36 hr of release in probes traps supplemented withattractant or repellents.

Fig. 7. Number of Adults of Rhizopertha dominica trappedafter 108 hr of release in probes traps supplemented withattractant or repellents.

indicates significant differences at selected levels(300, 600, 900, 1200, and 1500). It is quite visiblethat after 36 hours neem leaves trapped maximumand significantly higher populations 229.33 individuals/trap (Fig. 5). The population trapped after 72 hr wassignificantly higher i.e. 234.00 individuals/ trap fromtobacco filled probes (Fig. 6). Population trapped after108 hr was maximum in tobacco filled probes (164.33individuals/trap), but it had shown significant reductionfrom the previous values (Fig. 7). Therefore favoringthe best time to remove traps after 72 hr when filledwith tobacco leaves. Our studies are in completeagreement with those of Sanewe and Young (1999)who reported tobacco as a good repellent against

insects.It is thus concluded from the present findings that

probe traps are an effective way of trapping R.dominica and the performance of these can furtherbe enhanced if they are supplemented with driedleaves of neem or tobacco as repellent. It is alsoevident from present studies that neem and tobaccoleaves have better abilities to favor trapping providedthe trapped individuals are removed at proper timeas is clear from present studies. When using neemleaves the traps must be removed after 36 hr as theseyield maximum results, while with tobacco leaves 72hr favor higher traps.

212 J. Asia-Pacific Entomol. Vol. 6 (2003)

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