Modeling the dynamics of adaptation to transgenic corn by western corn rootworm (Coleoptera : Chrysomelidae)

A simulation model of the population dynamics and genetics of the western c orn rootworm, Diabrotica virgifera virgifera LeConte, was created for a lan dscape of corn, soybean, and other crops. Although, the model was created t o study a 2-locus problem for beetles having genes for resistance to both c rop rotation and transgenic cool, during this first phase of tile project, the model was simulated to evaluate only resistance management plans for tr ansgenic corn. Allele expression in the rootworm and toxin dose in the corn plant were the two most important factors affecting resistance development . A dominant resistance allele allowed quick evolution of resistance to tra nsgenic corn, whereas a recessive allele delayed resistance >99 yr. With hi gh dosages of toxin and additive expression, the time required to reach 3% resistance allele frequency ranged from 13 to >99 yr. With additive express ion, lon er dosages permitted tire resistant allele frequency to reach 3% i n 2-9 yr with refuges occupying 5-30% of the land. The results were sensiti ve to delays in emergence by susceptible adults and configuration of the re fuge (row strips versus blocks).