|BUKOWSKY, REBECCA - University Of Missouri|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2011
Publication Date: 12/19/2011
Citation: Frank, D.L., Bukowsky, R., French, B.W., Hibbard, B.E. 2011. Effect of MIR604 transgenic maize at different stages of development on western corn rootworm (Coleoptera: Chrysomelidae) in a central Missouri field environment. Journal of Economic Entomology. 104:2054-2061.
Interpretive Summary: Unexpected late-season damage has been seen with transgenic corn expressing an insecticidal protein, known as Bt, which is targeted toward the control of corn rootworms. This damage can be a major problem for corn producers in the U.S. In order to help determine if the cause of this damage was reduced levels of the insecticidal Bt protein late in the season, the effects of corn maturity on the establishment, damage, and adult emergence of the western corn rootworm from transgenic corn and a non-transgenic corn line (with the same genetic background) was evaluated in field trials. Overall, the results demonstrate that western corn rootworm larval recovery, root damage, and adult emergence were significantly lower for transgenic than non-transgenic corn, as expected. However, the size of larvae and adults recovered from transgenic and non-transgenic corn were generally not significantly different. The number of western corn rootworm larvae and adults collected from transgenic corn also did not significantly differ among egg hatch dates at widely varying corn maturities. Although the extractable level of the insecticidal Bt protein decreased significantly for older corn in previous studies, in the current study, the amount of toxin did not vary in a way that affected survival by western corn rootworm larvae in the field. This information is critical for understanding how Bt protein can be used to manage corn rootworms and is of importance to the development of insect management strategies for employment in protecting the security of U.S. corn production.
Technical Abstract: The establishment and survival of western corn rootworm, Diabrotica virgifera virgifera LeConte, was evaluated on transgenic Bt maize, Zea mays L., expressing the mCry3A protein (MIR604) and non-Bt maize with the same genetic background (isoline maize) at different stages of development in 2007 and 2008. Overall, western corn rootworm larval recovery, root damage, and adult emergence were significantly higher on isoline maize compared with MIR604. The number of larvae and adults collected from MIR604 did not significantly differ among egg hatch dates from each maize developmental stage evaluated in either year. In 2007, damage to isoline maize roots was lower than expected and never exceeded 0.24 nodes of damage. In 2008, over 0.60 nodes of damage occurred on isoline maize roots. The mean weight and head capsule width of larvae and adults recovered from MIR604 and isoline maize were generally not significantly different. Results are discussed in relation to insect resistance management (IRM) of western corn rootworm.