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Issue No. 10, Article 10/May 28, 2004

Field Observations on Soybean Aphids in Northern Illinois

David Voegtlin, an entomologist with the Center for Ecological Entomology, Illinois Natural History Survey, recently shared some observations on soybean aphids that he and Bob OíNeil, an entomologist with the Department of Entomology, Purdue University made during their excursions through northern areas of Indiana and Illinois. On May 6 and 7, they scoured the countryside in northeastern Indiana in search of soybean aphids on Rhamnus cathartica (common buckthorn) and Rhamnus alnifolia (native alderleaf buckthorn). They examined hundreds of plants and could not find a single soybean aphid. Keep in mind, during the last week of September of 2003, they had observed soybean aphids on these overwintering hosts in these locations. On May 26 and 27, David Voegtlin continued his search for soybean aphids on common buckthorn in northeastern Illinois. He surveyed several counties including Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will. During these two days, David looked at several thousand plants in woodlots in which "there was a carpet of buckthorn seedlings." Again, he could not locate a single soybean aphid! It was Davidís opinion that at least some aphids should persist into early June on buckthorn in these northern areas of the state. During Davidís survey, he observed very few fields of emerged soybeans north of Interstate 80. At this point, it remains uncertain what will become of soybean aphids during the 2004 growing season. Weíll continue to pass along observations throughout the year on this insect pest. Thanks to David Voegtlin and Bob OíNeil for their survey information!

Ramnus cathartica, the overwintering host of Aphis glycines.

--Mike Gray

Mike Gray

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