Despite the potentially profound impact of genetically modified crops on agriculture and the environment, we know little about their long-term effects. We present theoretical analyses showing that long-term suppression of pest populations following deployment of a Bt crop is governed by interactions among reproductive rate, dispersal propensity and regional abundance of a Bt crop. Supporting this theory, a ten-year study in 15 regions across Arizona shows that Bt cotton suppressed a major pest, the pink bollworm. Pink bollworm population density declined consistently only in regions where Bt cotton accounted for more than 65% of the cotton. Because regional abundance of Bt crops may affect refuge efficacy, rigorous field experiments are urgently needed to better understand how refuges should be deployed and managed, especially in regions where Bt crops are abundant.
Species 1: Lepidoptera Gelechiidae Pectinophora gossypiella (pink bollworm)
Keywords: Bacillus thuringiensis, Resistance
Back to Ten-Minute Papers, Section Cd. Behavior and Ecology, Cf. Quantitative Ecology
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Back to The 2003 ESA Annual Meeting and Exhibition