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Description of the sterile insect technique including a case study Siegrid Widhalm 24/01/2012 Applied Entomology in orchards, vineyards and horticultural crops 953.325 Definition • Biologically‐based method for the management of insect pests • „a method of pest control using area‐ wide inundative releases of steril insects to reduce reproduction in a field population of the same species“ • Sterile insects are not self‐replicating and therefore cannot become established in the environment http://www.nature.com/nbt/journal/v23/n4/fig_tab/nbt0405‐ 432_F1.html History • The entomologist E. Knipling exploited H. Muller´s discovery that ionizing radiation can induce dominate lethal mutations • This approach was first successfully applied on the New World screw‐ worm fly Cochliomyia hominivorax in the USA, Mexico and Central America (1957 – 1990) • Currently, the SIT is most widely applied against fruit flies. http://en.wikipedia.org/wiki/File:EdwardF.KniplingEntomologist.jpg Ionizing Radiation • Cobalt‐60 is a synthetic radioactive isotope of cobalt • Due to is half‐life of 5.27 years Co‐ 60 is not found in nature • Co‐60 decays to the stable isotope Ni‐60 by emitting two gamma rays • When gamma radiation breaks DNA molecules, a cell may be able to repair the damaged genetic material but within limits http://www.sciencephoto.com/media/210620/enlarge Advantages and Success stories • SIT does not introduce exotic species into an ecosystem • Economies of scale by using a area‐wide pest management • No use of pesticides and therefore no resistance???? • Direct benefits of screwworm fly eradication are estimated to be over $ 1.5 billion/ year, compared with a total investment of $ 1 billion • Mexico protects a fruit and vegetable export market of over $ 3 billion/year through an annual investment of ca. $ 25 million Drawback • Radiation treatment can affect the health of the male • The technique is species specific • Standard operating procedures of mass rearing and irradiation do not leave room for mistakes • SIT is a expensive method • Radioactive source as a(potential) biohazard Case study ‐ Moscamed • Mediterranean fruit fly Ceratitis capitata • It is native to the Mediterranean area • Appeared 1955 in Costa Rica, where it became established • By 1977 had penetrated into southern Mexico • In 1977 the United States, Mexico and Guatemala initiated Moscamed • This program is designed to suppress Medfly populations and reduce the risk of introduction into the United States Case study ‐ Moscamed Disinfection of the Mediterranean fruit fly eggs Ceratitis capitata Case study ‐ Moscamed 12 ml of eggs dispersed on 5kg diet Optimal larvae maturation at 25°C and 80% humidity Case study ‐ Moscamed Separation of larvae and diet Pupation will start at 20°C, 60% humidity and darkness Colouring for identification Packing for irradiation Case study ‐ Moscamed Radiation with 125 Gy, 40h before eclosion Case study ‐ Moscamed Adult males are released by airplane Approximately 500 million flies/week References • • • • • • • • http://www‐naweb.iaea.org/nafa/ipc/biological‐control.html http://en.wikipedia.org/wiki/Cobalt‐60 V.A. Dyck, J. Hendrichs and A.S. Robinson, Sterile Insect Technique. Principles and practice in area‐wide integrated pest management, Springer 2005 Vreysen, M.J.B.; Robinson, A.S.; Hendrichs, J. (Eds.), Area‐Wide Control of Insect Pests, 2007 http://www.iaea.org/newscenter/news/2011/battlingbugs.html Radioisotopes and Ionizing Radiations in Entomology Vol. IV 1966‐1967, Bibliographical series No. 36. STI/PUB/21/36, IAEA, Vienna 1969 The New World Screwworm Eradication Programme. North Africa 1988‐1992, Food and Agriculture Organization of the United Nations, Rome, Italy 1992 Sterility Principle for Insect Control 1974 [pdf]. STI/PUB/377, IAEA, Vienna 1975 Thanks for your attention