Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2004
Publication Date: N/A
Technical Abstract: The registration of transgenic corn with resistance to corn rootworm larval feeding offers a viable alternative to insecticides for managing the most economically important insect pests of corn. Recently, we have documented that the progeny of beetles that survived rootworm-resistant Bt corn (both parents, all larval instars), are much more likely to survive Bt corn than progeny of beetles from the same wild-type population that were not exposed to Bt corn. An understanding of larval survival on Bt corn and increased survival on Bt corn after previous exposure is crucial for the long-term durability of this management option. We are currently maintaining four nondiapausing colonies stemming from one wild-type × nondiapausing colony at USDA-ARS facilities in Columbia, Missouri. Each is fed optimally as adults, but differing in larval diet: 0) non-Bt (isoline) only, 1) exposed to Bt corn as neonates, but reared on isoline, 2) Bt corn only from second instar to pupation, and 3) reared solely on Bt corn. These colonies will facilitate a closer examination of the mechanism of survival of western corn rootworm larvae on Bt corn. Currently, each of the above colonies is thriving, and extra eggs are available for collaborators. Larvae from each of the above colonies will be evaluated for survival on Bt and isoline corn, for changes in feeding behavior on Bt and isoline corn in a semi-solid transparent growth media, and for physiological effects on Cry3Bb1 artificial diet. In addition, binding proteins for Cry3Bb1 will be identified from WCR midguts and two approaches with selected and susceptible WCR strains will be used to identify those proteins associated with changes in susceptibility. An understanding of WCR/Bt corn interactions can serve as a model system for understanding other low-dose transgenic events. This information will be important to seed companies, the Environmental Protection Agency, and modelers in their attempts to develop resistance management plans for transgenic corn by providing more realistic assumptions in current mathematical models.