The effect of delay of adult emergence in Bt corn on resistance evolution of western corn rootworm, Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae)

The delay of emergence and the female-skewed-sex-ratio of adults of Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae) from Bt corn have been reported in field studies. We used a simulation model to study the effect of delay of adult emergence from Bt corn and the female-skewed-sex-ratio of adults emerging from Bt corn on evolution of Bt resistance of D. v. virgifera. Forward-shift of the time of emergence of beetles of the genotypes with a resistant allele from Bt corn accelerates evolution of Bt-resistance, but backward-shift (delay) of the time of emergence of beetles of the genotypes with a resistant allele from Bt corn slows down evolution of Bt-resistance. Shift of the time of emergence of homozygous-susceptible beetles from Bt corn does not have a significant effect on the evolution of Bt-resistance of D. v. virgifera. Bt resistance evolves slightly faster when males are more susceptible to Bt toxin than females.