No. 11 Article 3/June 6, 2008

Just In--Rootworm Larvae Detected in Indiana

We entomologists in Illinois almost always rely on the careful observations of Larry Bledsoe, research entomologist at Purdue University, for the first report of rootworm larvae during any given season. Just as articles for this issue of the Bulletin were due to the editors, Larry notified us and other Midwest colleagues that he had found first instar corn rootworms on June 4 in Tippecanoe County, Indiana. He and his crew had been examining about 100 plants per day since May 28, and they finally struck pay dirt. Larry estimated that emergence began in his area in 2008 no sooner than June 2, about two weeks later than his observation of first hatch in 2007. Review Mike Gray's article "Late Corn Rootworm Larval Hatch Anticipated This Spring" in issue No. 9 (May 23, 2008) of the Bulletin to find comparisons of first rootworm larval hatch among the years 1996 to 2007.

It will be interesting to find out how rootworms are affected by the torrential rains we just experienced in much of Illinois on June 3 and 4. Research has revealed that first instars that hatch into flooded or saturated soils do not fare well--they cannot locate corn roots, or they drown. Rootworm eggs, on the other hand, have been known to survive flooded or saturated soil conditions. In areas where saturated soils are common, it is likely that rootworm larval populations will experience considerable mortality. So maybe there's a bit of good news associated with this excessive rainfall. --Kevin Steffey

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