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What Can We Expect From Soybean Aphids This Year?

March 16, 2001
Consider that a mere 7 months ago we were embroiled in a lot of activity focused on an aphid that was not known to occur in North America before 2000. The soybean aphid, Aphis glycines, invaded soybean fields throughout the upper Midwest, primarily in northern Illinois, northwestern Indiana, southeastern Michigan, southwestern Minnesota, and southern Wisconsin. Surveys in August and September 2000 revealed that the aphid, an "import" from Asia, spread rapidly into other states as well: Iowa, Kentucky, Missouri, and Ohio. The aphid was found as far east as West Virginia.

We learned that the primary overwintering host for the aphids is buckthorn, several species of Rhamnus. Late in the summer, winged soybean aphids leave soybean fields to seek buckthorn plants, where the aphids reproduce sexually to produce eggs that will overwinter. In the spring, the aphids will spend two generations on buckthorn; the third generation will produce winged forms that will fly away to seek soybean as their summer host.

The burning question is, "Will the soybean aphid survive winters in the Midwest?" We suspect that they will; after all, they survive the winters in northeastern Russia and Korea. However, we are not certain if the soybean aphid will adapt to our native species of Rhamnus. If they do, we can anticipate more occurrences of soybean aphids in 2001.

We still have much to learn about this new pest of soybean, but we are poised to learn as much as we can in 2001 if infestations in soybean fields develop. A large team of scientists in the College of ACES at the University of Illinois, USDA-ARS in Champaign-Urbana, and the Illinois Natural History Survey is prepared to conduct a considerable amount of research this year. One of our initial efforts will be to establish tall suction traps that will sample flying aphids at six different locations in the state. Entomologists and plant pathologists in nearby states will embark on similar efforts. Trapping and field monitoring activities during the spring should enable us to determine when the aphids are leaving buckthorn for soybean. Hopefully this early-warning system will help us in our efforts to help you learn more about this intriguing pest.

Stay tuned for updates throughout the season.--Kevin Steffey

Author: Kevin Steffey

The Pest Management and Crop Development Bulletin
Executive Editor: Kevin Steffey, Extension Entomologist

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