2009 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. 3.Progress Report To clearly define specific accomplishments and future goals, this report is arranged according to the objectives contained in the original proposal, with each goal restated below. 1. 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. Two laboratory studies and one semi-field study have been completed with Cry1Ab-resistant European corn borers and single-toxin corn hybrids. Laboratory and semi-field experiments are ongoing for Cry1F-resistant European corn borers and single-toxin corn hybrids. The results for the Cry1Ab studies have been outlined in two publications, but generally indicate genotype-specific differences in movement and survival of corn borer larvae. 2. Evaluate how resistance allele frequencies influence entry into diapause, overwintering survival, and timing of European corn borer adult emergence. Diapause experiments with Cry1Ab-resistant larvae have been completed. Trials with a Cry1F-resistant colony will begin in the fall. Publications: Thus far, two manuscripts have been published as a result of this research. They are reported in the parent project. This project was monitored with frequent telephone calls and e-mail correspondence.