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item Hibbard, Bruce

Submitted to: Entomological Society of America Annual Meeting North Central Branch
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2005
Publication Date: 3/20/2005
Citation: Hibbard, B.E., Clark, T.L. 2005. Dose/selection intensity of cry3bb1 and cry34/35: Comparison and status of cry3bb1 colonies [abstract]. Entomological Society of America Annual Meeting North Central Branch.

Interpretive Summary:

Technical Abstract: The registration of transgenic corn with resistance to corn rootworm (MON863) larval feeding offers a viable alternative to insecticides for managing the most economically important insect pests of corn. In a series of small scale field studies, we evaluated adult production from MON863 and compared this to adult production from an isoline corn under the same artificial infestation levels in nine locations in 2003 and 2004. When averaged across two infestation levels, two replications, and nine locations, adult emergence from the MON863 was 1.4% of adult emergence from isoline. Adults from each of these locations were kept alive and allowed to lay eggs. Progeny of beetles that survived MON863 and those that survived isoline corn were then evaluated in greenhouse studies. Progeny of beetles that survived MON863 (both parents, all larval instars), were 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, MO. 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. The current status of the colonies as well as implications of the data will be discussed.