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ADVERSE IMPACTS OF TRANSGENIC CROPS/FOODS :A COMPILATION OF SCIENTIFIC REFERENCES WITH ABSTRACTS9. Downes S, Parker T and Mahon R (2010) : Incipient resistance ofHelicoperva punctigera to the Cry2Ab Bt toxin in Bollgard II cotton. PLoSOne 5(9) : e12567.Combinations of dissimilar insecticidal proteins (“pyramids”) within transgenicplants are predicted to delay the evolution of pest resistance for significantlylonger than crops expressing a single transgene. Field-evolved resistance toBacillus thuringiensis (Bt) transgenic crops has been reported for first generation,single-toxin varieties and the Cry1 class of proteins. Our five year data set showsa significant exponential increase in the frequency of alleles conferring Cry2Abresistance in Australian field populations of Helicoverpa punctigera since theadoption of a second generation, two-toxin Bt cotton expressing this insecticidalprotein. Furthermore, the frequency of cry2Ab resistance alleles in populationsfrom cropping areas is 8-fold higher than that found for populations from noncroppingregions. This report of field evolved resistance to a protein in a dualtoxinBt-crop has precisely fulfilled the intended function of monitoring for resistance;namely, to provide an early warning of increases in frequencies that may lead topotential failures of the transgenic technology. Furthermore, it demonstrates thatpyramids are not ‘bullet proof’ and that rapid evolution to Bt toxins in the Cry2class is possible.10. Caccia S, Hernandez-Rodríguez CS, Mahon RJ, Downes S, James W, et al.(2010) : Binding Site Alteration Is Responsible for Field-Isolated Resistanceto Bacillus thuringiensis Cry2A Insecticidal Proteins in Two HelicoverpaSpecies. PLoS ONE 5(4) : e9975Evolution of resistance by target pests is the main threat to the long-term efficacyof crops expressing Bacillus thuringiensis (Bt) insecticidal proteins. Cry2 proteinsplay a pivotal role in current Bt spray formulations and transgenic crops and theycomplement Cry1A proteins because of their different mode of action. Theirpresence is critical in the control of those lepidopteran species, such asHelicoverpa spp., which are not highly susceptible to Cry1A proteins. In Australia,a transgenic variety of cotton expressing Cry1Ac and Cry2Ab (Bollgard II)comprises at least 80% of the total cotton area. Prior to the widespread adoptionof Bollgard II, the frequency of alleles conferring resistance to Cry2Ab in fieldpopulations of Helicoverpa armigera and Helicoverpa punctigera was significantlyhigher than anticipated. Colonies established from survivors of F 2screens againstCry2Ab are highly resistant to this toxin, but susceptible to Cry1Ac.11. Ranjith MT, Prabhuraj A and Srinivasa YB (2010) : Survival and reproductionof natural populations of Helicoverpa armigera on Bt-cotton hybrids inRaichur, India. Current Science, Vol. 99 (11).Transgenic Bt-cotton is commercially cultivated on the rationale that it producestoxins that defend the plants primarily from caterpillars damaging cotton bolls.From the context of crop protection, it is important that these bollworms remainsusceptible to the toxins, so that their populations are under check. However, if(128)