2011 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 Laboratory and field experiments were conducted on neonates (recently emerged larvae) and late instars (older larvae) to evaluate movement of larvae among corn hybrids at high population densities. Follow-up experiments are ongoing to evaluate late instar movement at high and low larval densities. Laboratory experiments were conducted to evaluate pre-dispersal tasting mortality of neonates and third instars using Bacillus thuringiensis (Bt) and non-Bt tissues. Diapause and adult emergence experiments with Cry1Ab-resistant larvae and Cry1F resistant larvae have been completed. The project is related to the objective "Improve knowledge of the ecology, genetics, and behavior of corn pests such as corn borer, corn rootworm, and western bean cutworm in relation to pest abundance and insect resistance to transgenic corn" of the in-house project (3625-22000-017-00D). Progress was monitored with phone calls, emails, and discussions with collaborators at professional meetings.