Transgenic crops producing Bt toxins are now planted on millions of
hectares in the United States and elsewhere. Widespread use of Bt crops
places strong selection on pests to evolve resistance. Tactics to prevent
the evolution of resistance have been explored extensively through the use
of computer simulations and nearly all models suggest that the evolution of
resistance can be delayed, but is inevitable. The key output in many models
is the time required for the resistance allele to reach a frequency of
fifty percent. However, as resistance increases in a region, decreased
efficacy of Bt crops may be detected by growers or by monitoring programs
before the resistance allele reaches a frequency of fifty percent. If so,
remedial action to prevent the spread of resistance may be taken. The
Arizona Bt Cotton Working Group has been developing remedial action plans
to prevent the spread of resistance once it is detected in field
populations of the pink bollworm (Pectinophora gossypiella). There are two
key components to remedial action plans. The first is the level of
resistance that can be detected. The second is the effectiveness of the
remedial action on eliminating the discovered resistant population. We
used computer simulations of a spatially explicit model of our system to
explore how these two variables affect the success of remedial action
plans. The results will allow us to better determine methods to deal with
resistance once it has been observed.
Species 1: Lepidoptera Gelechiidae Pectinophora gossypiella (pink bollworm)
Species 2: Bacillus thuringiensis (Bt)
Keywords: Bacillus thuringiensis, transgenic crops
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA