Chemical-free control of diamondback moth

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The diamondback moth, Plutella xylostella (DBM), is a major pest of brassicas (e.g. cabbage, cauliflower, broccoli, radish, mustard) worldwide, feeding on the leaves and causing significant economic damage in many countries. Current control activities largely rely on insecticide use, including microbial pesticides such as Bt. Unfortunately, DBM has developed resistance to most front-line insecticides, including Bt. However, DBM is considered one of best candidates for the Sterile Insect Technique (SIT) as part of an area-wide integrated control approach, but several limitations of the conventional SIT approach limit its widespread utilisation [1-2]. SIT relies on the mass rearing, sterilisation using irradiation and release of large numbers of the sterile males over the target area [1, 3]. Released sterile males mate with wild females, reducing the reproductive potential of the wild population and so causing a reduction in the wild population in the subsequent generation. If enough sterile males are released for a sufficient time, the target population will collapse. Conventional SIT relies on irradiation to sterile the target pest species. However, the ionising radiation required to induce sexual sterility in Lepidoptera often impairs mating behaviour to such an extent that the males are not viable within an SIT programme [4-5]. Furthermore, there is currently no genetic sexing mechanism, which means males and female F1 progeny are both reared within the programme facilities, increasing production costs and decreasing effectiveness as sterile females 'distract' sterile males from seeking wild females [6-7]. Oxitec's core proprietary technology, known as RIDL (Release of Insects with Dominant Lethal), first demonstrated in Drosophila[8] and now being applied to real pest insects [9-10], provides a viable means of overcoming the limiting constraints of SIT for DBM. The student will develop RIDL strains of diamondback moth that replace the need for sterilisation by irradiation and also act as a genetic sexing mechanism [11]. The proposed research will benefit from the unique expertise within Oxitec of generation of RIDL strains of other pest species including pink bollworm and Medfly, our unique ability to transform DBM, and the extensive experience of insect molecular genetics and transformation in both the academic and company laboratories. Genetic engineering of insect pests is in its infancy (e.g. first transformation of any moth was published as recently as 2000 [12]), and this project is at the cutting edge of applied insect genetics. Our experience with other insects now enables us for the first time to address these issues with a realistic hope of developing a novel, sustainable, low-environmental-impact pest control strategy for a pest of great economic importance. References 1. Dyck et al, eds. Sterile Insect Technique: principles and practice in area-wide Integrated Pest Management. 2005, Springer 2. IAEA, 'Improvement of Codling moth SIT to facilitate expansion of field application.' 2000, IAEA: Vienna, Austria. p. 33 3. Knipling, E., J. Econ. Entomol., 1955. 48:459 4. Robinson, A., Mut Res, 2002. 511:113 5. Bloem, K.A., et al in Dyck, et al (eds) 2005, Springer 6. Rendón, P., et al. J Econ. Entomol., 2004. 97:1547 7. Marec, F., et al.. J. Econ. Entomol., 2005. 98: 248 8. Thomas, D.D., et al. Science, 2000. 287:2474 9. Gong, P., et al. Nat. Biotech., 2005. 23:453 10. Fu, G., et al. Nat. Biotech, 2007. 25:353 11. Alphey, L., (2008) in 'Transgenesis and the management of vector-borne disease', Aksoy (ed) Landes Bioscience 12. Peloquin, J.J., et al. Insect Mol. Biol., 2000. 9:323