No. 23 Article 3/October 9, 2009

European Corn Borer Survey Conducted Once Again

Under the direction of Kelly Estes, an entomologist with the Illinois Natural History Survey, the fall survey of European corn borers was conducted once again. Early reviews of data indicate that densities were exceedingly low in some counties. We intend to share the full results in the November issue of the Bulletin. We have conducted this annual survey 11 times since the introduction of Bt hybrids. Data from the combined surveys seems to point in the direction that the widespread use of Bt hybrids has had a significant suppression effect on populations of this once-major insect pest of corn. Next year we may discontinue the survey to instead focus our survey efforts on western corn rootworm adults during the summer.

Many questions were raised this summer across the Corn Belt concerning the low densities of western corn rootworm adults. We have some historical data of western corn rootworm populations across Illinois, and it may be interesting to begin comparing these data pre-Bt and post-Bt. The very wet spring across much of the state may explain some of the low numbers observed in 2009. However, as more corn acres (first-year corn and continuous corn) are planted to Bt hybrids or treated with soil insecticides, we may be witnessing an areawide suppression of this insect pest as well.--Mike Gray

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