2010 Annual Report 1a.Objectives (from AD-416) Evaluate the role of feeding behavior of WCR larvae that are resistant to Cry3Bb1 transgenic corn in their resistance. 1b.Approach (from AD-416) A series of experiments will be conducted in order to support or refute the assertion that western corn rootworm feeding behavior plays a role in their survival on transgenic Cry3Bb1-expressing corn. Approaches will include direct observation, carbon isotope analysis of western corn rootworm larvae fed mixtures of Bt corn and cool season grasses for various lengths of time, cross sectioning Bt and isoline roots fed by resistant and susceptible rootworm larvae to see if they feed on different root tissue, and related follow-up experiments. 3.Progress Report To date, host recognition behavior has been evaluated for all currently-registered transgenic maize and targeted toward WCR and paired isoline maize without the Bt genes using susceptible WCR. No significant difference was found between Bt lines and their corresponding isoline maize lines in terms of total distance traveled, velocity, meander, or turn angle. All maize was significantly different than filter paper and oat controls. Bioassays for evaluating the role of feeding behavior of lines of the western corn rootworm with resistance to transgenic corn are under development. Monitoring activities include nearly daily personal conversations with the GRA and personal meetings with the co-PI as needed.