ARS | Publication request: Mortality impact of MON863 transgenic maize roots on western corn rootworm larvae in the field

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 19, 2012
Publication Date: December 7, 2012
Citation: Clark, T.L., Frank, D.L., French, B.W., Meinke, L.J., Moellenbeck, D., Hibbard, B.E. 2012. Mortality impact of MON863 transgenic maize roots on western corn rootworm larvae in the field. Journal of Applied Entomology. 136:721-729.

Interpretive Summary: 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. Maintaining insect susceptibility to transgenic crops (resistance management) is in the interest of growers, the Environmental Protection Agency, and the industry, but requires an understanding of corn rootworm biology that does not currently exist. The mortality of the western corn rootworm larvae due to feeding on transgenic corn expressing insecticidal proteins relative to survivorship on the same genetic background of non-transgenic control corn was evaluated in nine U.S. Corn Belt environments. An average of 788 beetles emerged from control plots at the lower infestation level while the average beetle emergence from the transgenic line (MON863) was 12 when averaged across 18 replications in nine environments. There was an 18 d delay in time to 50% beetle emergence from the transgenic line compared to the control. Our results suggest that the trangenic corn expressing an insecticidal protein is effective in corn root worm control in the field. These quantitative data are required by the Environmental Protection Agency and are important to seed companies and modelers in their attempts to optimize resistance management plans for transgenic corn.

Technical Abstract: Mortality of western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae due to feeding on MON863 transgenic maize (Zea mays L.) expressing the Cry3Bb1 protein relative to survivorship on maize with the same genetic background without the gene (isoline maize) was evaluated at three Missouri sites in both 2003 and 2004 and at one site each in South Dakota, Nebraska, and Iowa in 2004. Comparisons were made using the western corn rootworm at low (1,650 - 2,500 eggs/m) and high (3,300 - 3,500 eggs/m) egg densities. As expected, significantly fewer beetles were recovered from MON863 than isoline maize. Emergence as a percentage of viable eggs ranged from 0.02 to 0.10% from MON863, whereas emergence from isoline maize ranged from 1.09 to 7.14%. Mortality due to the Cry3Bb1 protein was 98.49% when averaged across all environments and both years. The time delay to 50% beetle emergence from MON863 averaged 18.3 d later than 50% beetle emergence from isoline maize. Overall, our results showed that females comprised 56 and 71% of total beetles recovered from MON863 in 2003 and 2004, respectively. Results are discussed in relation to insect resistance management (IRM) of western corn rootworm.