Diamondback moth resistance to Bacillus thuringiensis transgenic canola: evaluation of refugia size with non-recessive resistant insects |
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| Authors: | H. Cerda A. H. Sayyed D. J. Wright |
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| Affiliation: | Universidad Simon Rodriguez, IDECYT, Caracas, Venezuela;;Department of Biochemistry, Faculty of Life sciences, University of Sussex, Falmer, Brighton;;Division of Biology, Faculty of Natural Sciences, Imperial College London, Silwood Park campus, Ascot, UK |
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| Abstract: | Abstract: Current recommendations to delay the evolution of resistance to Bacillus thuringiensis crops are that a minimum of 5–50% of a crop-growing region should include non- B. thuringiensis varieties as refuges. These recommendations are based in part on the assumption that resistance will be inherited as a recessive trait. Laboratory microcosm experiments are described with transgenic canola expressing Cry1Ac and a non-recessive Cry1Ac resistant population of the diamondback moth Plutella xylostella , in which the effect of different sizes of refugia (0%, 20% and 50%) on resistance was compared over five generations. The LC50 values for Cry1Ac increased markedly in the P. xylostella sub-populations with 0% (>100-fold) and 20% refugia (>35-fold) but showed little change (less than fivefold increase) with 50% refugia. The results support the idea that relatively high levels of refugia (non- B. thuringiensis varieties) may be required where resistance is not functionally recessive at the level of toxin expressed in the B. thuringiensis crop. |
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| Keywords: | Bacillus thuringiensis Plutella xylostella resistance management refugia transgenic crop |
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