STERILE INSECT TECHNIQUE

Presented by: K.SANKARA RAO 13-503-003

INTRODUCTION

HISTORY AND DEVELOPMENT

CURRENT TARGETS

MASS REARING

INDUCTION OF STERILITY

FIELD RELEASE AND EVALUTION

ADVANTAGES AND LIMITATIONS

CONTENTS OF PRESENTATION(SIT)

Insect pests contribute significantly to the high prevalence of undernourishment in the world.

New, innovative pest control tactics and strategies are therefore needed that are both effective and not detrimental to the environment.

As part of the of environmentally-friendly control tactics, the sterile insect technique (SIT) has proven to be a very effective tool pest management.

INTRODUCTION

Use where Insect pests for which effective and affordable alternative controls are not available (Lance and McInnis,2005).

BIOLOGICAL CONTROL

GENETIC CONTROL

HYBRID

STELITY

CYTOPLASMIC INCOMPATABILITY

STERLIE INSECT TECHNIQUE

LETHAL MUTATIONS

MEIOTIC DRIVE

MECHNISMS

CHROMOSOMAL

REARRANGEMENT

STERILE INSECT TECHNIQUE

NORMAL FEMALE

STERILE MALE

UNFERTILISED EGGS

Continued sterile male releases ,the population decline

Ratio of sterile to normal male increases until no nomal male remain.

The population becomes extinct for lack of progeny

Sterile Insect Technique is the method of genetic control comes broadly under biological control

Eradication of pest not merely suppression(Hendrichs et al., 2005) (usually crop pests or human and animal pests)

Autocidal control

OBJECTIVE OF SIT

PRINCIPLE OF SIT

Sterile Insect Technique (SIT) was initiated by E.F. Knipling and R.C. Bushland in the 1930s

They worked with the screwworm fly, a devastating pest of cattle in North America.

Bushland initially researched chemical treatment of screwworm-infested wounds in cattle

Knipling developed the theory of autocidal control – breaking the life cycle of the pest itself.

The first successful use of SIT to control screwworm was on the island of Curaçao in 1953.

Development of the sterile insect technique

screwworm fly life cycle

FEMALE SCREWWORM MATES ONLY ONCE IN HER LIFETIME

REASON BEHIND THE SUCCESS OF SIT

HYPOTHETICAL MODEL DEVELOPED BY KNIPLING

GENERATIONNATURALPOPULATION

STERILE INSECTS RELEASED S:F

MATINGS

INFERTILE %PROGENY

NO.OF FERTILRE

1 1000 2000 2:1 665.1 3332 333 2000 6:1 85.7 47

3 47 2000 42:1 97.7 14 1 2000 2000:1 99.9 0

Sterile insects have a unique biological advantage that matches them very well to the concept of eradication, i.e. their effectiveness increases as the pest population declines in numbers: their action is inversely dependent on the density of the target population (Dame, 1970).

USE OF SIT IN IPM

In 1954, the technique was used to completely eradicate screwworms from the 176-square-mile (460 km2) island of Curaçao

Screwworms were eliminated in a span of only seven weeks, saving the domestic goat herds that were a source of meat and milk for the island people.

SUCCESSFUL ERADICATION OF SCREWWORM

During the 1960s and 1970s, SIT was used to control the screwworm population in the United States.

The 1980s saw Mexico and Belizium eliminate their screw worm problems through the use of SIT

In 1991, Knipling and Bushland's technique halted a serious outbreak in northern Africa.

Screw worm erdication……..

Success stories

Screwworm fly (Cochliomyia hominivorax) eradicated from the United States, Mexico, and Libya

Mexican fruit fly (Anastrepha ludens) eradicated from most of northern Mexico.

Tsetse fly eradicated from Zanzibar

Medfly (Ceratitis capitata) from northern part of Chile and southern part of Peru and southern part of Mexico.

Melon fly (Bactrocera cucurbitae, Coquillett) eradicated from, Japan

The sterile fly is an innovative solution to the problem of the African trypanosomiasis

Anopheles sp.

Aedes sp

TARGET INSECTS

Medfly Ceratitis capitata

Painted Apple Moth Teia anartoides

Codling moth Cydia pomonella

Tsetse fly Glossina spp

Mexican fruit fly Anastrepha ludens

SL.NO COMMON NAME ENTOMOLOGICAL NAME

REASON OF RELEASE place1. Mosquito Anopheles sp. MALARIA vector AFRICA2. Mosquito Aedes sp. vectors for filariasis dengue

and yellow feverAFRICA

3. Painted Apple Moth Teia anartoides Borer pest of apple

NEW ZEALAND4. Codling moth Cydia pomonella BRITISH COLUMBIA,

CANADA

5. Tsetse fly Glossina spp sleeping sickness vector

6. Mexican fruit fly Anastrepha ludens USA

7. Medfly Ceratitis capitis8. Queensland fruit

flyBactrocera tryoni AUSTRALIA

9. other Bactrocera sp. ASIA

CURRENT

TARGETS

MASS REARING OF INSECTS

Research toward mass production must emphasize on

1.Food or rearing media 2.Techniques for extracting all stages from the media3.Techniques to avoid crowding 4.Information on mating and oviposition behaviour5.Rearing room islolation6.Maximum automation

Mediterranean fruit fly mass-rearing facility in El Pino, Guatemala

Heat treatment of eggs Racks of cages with adult flies Larval rearing trays

Attention need at rearing: Selection of artificial diet Waste disposal Biosecurity in a pest free area

Mass production of sterile insects across the globe

source:Marc J.B. Vreysen*, Alan S. Robinson(2010)

Commonly using method

Both sexes are irradiated ,sterilized and released but sterile females have no desired effect on outcome, because species vary in the dose of radiation

Pupal stage appropriate stage for irradiation(Holometaba)Lastal nymphal instar (Hemimetabola)

Sources : x-rays Gama-rays

IRRADIARTION

Mode of action:Radiation induces dominant lethal mutations in normal sperm and in sperm carrying unbalanced chromosomes at equal frequency and in an exponentialmanner. (Franz,2000)

Ionising radiation also causes mutations in somatic cells

This impacts on the overall quality of the insect after radiation expressed as the development of abnormalities,a reduction in lifespan, flight ability, mating propensity, etc. (Bakri et al., 2005).

Sensitivity levels of insects to ionising radiation are affected by the level of oxygen present during irradiation (Economopoulos, 1977; Fisher, 1997)

.

IRRADIARTION cont…….

Sterilizing effects of x-rays on insects had been observed as early as 1916 with cigarette beetle results infertile eggs

After 10 years effect on drosophila also observed by generation of mutations lead discovery of x-ray impact on screw worm pupae by Bushland.

Mutations a s a result of complex injury in the sperm.

In 1950 screw worm pupae were irradiated at a dose of 2500 R

X-rays

After world war –(2 ) isotopes availabity helps in use of gama radiation

Commonly used sources are cobalt- 60 and Cesium-137

Availability of cobalt-60 sources was an important factor.

Effect as same as x rays but decrease the longevity of males

GAMA RAYS:

PROCEDUREScientific name Common name stage Sterilising dose(rads)

Musa domestica House fly 2-3 days pupal 3000

Cochliomyia homnivorax Screwworm fly 5 days pupae1day adult

2500

Drosophila melanogaster Fruit fly Adult males 5000-7000

Culex quinquefasciatus House mosquito pupae 11000-12000

Apis mellifera Italian honeybee Adults 7700Sitophilus oryzae Rice weevil 7-days adults 7500-11000Tribolium confusum Confused flour

beetleOld pupae 4000

Chemosterilants divided into 4 basic groups 1)Alkylating reagents- Largest class -ex: Aholate,Aphomate,Aphoxide 2)Phosphorous amides 3)Traizines 4)Antimetabolites ex:5-Fluorouracil,2-Thiouracil

cause multiple dominant lethal mutations or severely injured genetic material in sperm or egg

TEPA-House fly control(1962)Aholate-cotton boll weevil.Recently Diflubenzuron using as chemosterilant in adult diet along with gama radiation

CHEMOSTERILISATION

Mode of action

Techniques for release

1.Aeril release-using aircrafts2.Ground release

If the release is delayed ,survival can be increased by chilling treatment

All-terrain vehicle (ATV)

EVALUATION OF SIT PROGRAMME

1.Male fly sterility checking at laboratory

2.Performance of sterile insects in field.

Conditions for effective SIT

•An effective and reasonably economic method of mass rearing of the target insect.

• The released insect must disperse rapidly through the wild population.

• Sterilization must not affect sexual competitiveness • Females preferably mate only once. • It must be possible to overwhelm the native population with sterile insects (ratio of sterile to fertile fertile males of at least 10:1, preferably higher)

1. The most target-specific

2. Non-disruptive method

3. It uses no chemicals,leaves no residues

4. Species specific

5. Does not release exotic agents into environments

6. Does not even introduce new genetic material into existing populations7. improve the quality and quantity of fruit production while reducing

pesticide use and promoting ipm

ADVANTAGES:

Costs of production [the major drawback] Must provide reliable sterilization Must have reliable supply of sterile insectsRegional cooperation Released insects must be competitive with wild Insects for

mating Lab rearing quality control issuesSterilization quality control issuesSterile insects should not inflict direct damageRe-invasion of sterility zone

LIMITATIONS WITH SIT

Use of juvenile hormone including methoprene and fenoxycarb and protein diets in mass-rearing.

Use of genetic sexing strains(GSS)

Conditions for effective SIT…..

The introduction of the filter rearing system (FRS) into GSS mass rearing

Ionising radiation and area-wide management of insect pests to promote sustainable agriculture. A review -Marc J.B. Vreysen*, Alan S. Robinson

Mass rearing history and irradiation affect mating performance of the male fruit fly, Anastrepha obliqua -Juan Rull*, Nery Encarnación, and Andrea Birke

Sterile Insect Technique for Suppressing and Eradicating Insect Population: 55 Years and Counting- -E. S. Krafsur

Genetic sexing strains in medfly, Ceratitis capitata, sterile insect technique programmes - A.S. Robinson

References