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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