2012 Annual Report
1a.Objectives (from AD-416):
Assess the effects of resistance alleles on the frequency, timing, and survival of interplant movement by European corn borer larvae on single- and multiple-toxin Bt hybrids. Evaluate how resistance allele frequencies influence entry into diapause, overwintering survival, and timing of European corn borer adult emergence.
1b.Approach (from AD-416):
European corn borers resistant to Bt corn will be used to measure the impact of Bt resistance alleles on survival, development, and behavior. Experiments will examine how resistance alleles affect the frequency, timing, and survival of interplant movement by larvae on non-Bt, current Bt hybrids, and pending Bt hybrids ("pyramids"). The effects of Bt resistance alleles on corn borers entry into diapause, winter survival, and timing of adult emergence by overwintering generations also will be assessed.
Activities this year have focused on studying the dispersal of older larvae (late instars) of European corn borer on vegetative corn. The late instar studies confirm last year’s results that under high density conditions larvae will disperse during each of the five instars. Most of the dispersal occurs with first instars and appears to be density independent. High dispersal percentages also were found for older larvae, particularly fourth and fifth instars.