The theory of insecticide resistance management relies heavily on models. Many of these models include the assumptions that population size is effectively infinite and population dynamics and changes in resistance gene frequency are deterministic. However, large-scale adoption of a transgenic insecticidal crop, such as cotton that produces Bacillus thuringiensis (Bt) toxin Cry1Ac, reduces pest population size, making such assumptions inappropriate. For example, genetic drift is more important in small populations. As a result, the frequency of resistance alleles could increase or decrease by chance when local population size is small. We examined the effect of initial population size and operational factors that influence population size on the evolution of resistance with a spatially explicit, stochastic, simulation model based on the pink bollworm (Pectinophora gossypiella)/Bt cotton system. Our results suggest that manipulation of population size can help to delay evolution of resistance.
Species 1: Lepidoptera Gelechiidae Pectinophora gossypiella (pink bollworm)
Keywords: resistance management, transgenic crops
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