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Issue No. 9, Article 4/May 21, 2004

A Brief Summary of Soybean Aphid News

Word about soybean aphid eggs hatching on buckthorn has spread throughout the Midwest, so now seems like an appropriate time to summarize the information. David Voegtlin, our resident aphid research specialist at the Illinois Natural History Survey, observed the first soybean aphid hatch of the season on March 27 in eight cages of his winter host trial. On April 26, he observed third-generation winged aphids in abundance on buckthorn. Chris DiFonzo, entomologist at Michigan State University, observed soybean aphid hatch on April 17 in central Michigan. Tom Hunt, entomologist at the University of Nebraska, observed soybean aphids on buckthorn near Lincoln on April 23.

Three to four generations of soybean aphids develop on buckthorn in the spring. So the aphids are ready, but what about the soybeans? The abundant third-generation soybean aphids David Voegtlin observed on April 26 were well ahead of most soybean emergence in east-central Illinois. If soybean aphid populations are developing on buckthorn elsewhere in Illinois (as surely they must be), those aphids, too, are only just now able to find soybean seedlings. When soybean aphids finally find soybeans, they will begin colonizing the plants--sometimes very young plants.

It's much too early to tell whether populations of soybean aphids will develop to threatening levels later in the summer. Predation by multicolored Asian lady beetles (and there are plenty of them around) will play a role in population regulation, and weather, of course, also will influence soybean aphid development. But it's not too early to make preparations to scout for soybean aphids--early and often. Many people were caught by surprise in 2003 because they did not begin monitoring soybean fields early enough. Early-season aphid sightings are not cause for panic, but they help establish the initial timing of colonization. So prepare now, and stay vigilant throughout the next several weeks.--Kevin Steffey

Kevin Steffey

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