Agricultural Research Service (ARS) scientists and colleagues are getting a better handle on the basic biology, impact and migration of a new aphid species pestering soybean crops in Illinois and other nearby states.

The aphid, identified as Aphis glycines from Asia, first came to researchers' attention during the summer of 2000. Initially, there was speculation it belonged to aphid species that infest cotton and melon crops, notes Glen Hartman, a plant pathologist at ARS' Soybean/Maize Germplasm, Pathology, and Genetics Research Unit in Urbana, IL.

To help clear up the matter, entomologists Manya Stoetzel and David Voegtlin examined specimens of the mystery aphid under a microscope for tiny structures on the pest's body that can differentiate one aphid species from another. Stoetzel works at ARS' Systematic Entomology Laboratory in Beltsville, MD. Voegtlin is at the Illinois Natural History Survey in Champaign.

With the aphid's identify determined, Hartman, ARS scientists Leslie Domier and Loyd Wax, and University of Illinois colleagues are closely monitoring the pest's movement, damage to soybeans, and importance as an insect vector of soybean virus pathogens.

Aphids alone are destructive pests. But their ability to infest plants with so many different kinds of viruses makes them a twofold menace to crops. Two viral cohorts that scientists accuse A. glycines aphids of transmitting are the soybean mosaic virus and soybean dwarf virus.

Now that the Asian aphid's presence is known, plant breeders can begin evaluating soybean germplasm lines for resistance to the pest.

A more detailed story about this new aphid appears in this month's issue of Agricultural Research magazine on the World Wide Web at: www.ars.usda.gov/is/AR/archive/may02/aphid0502.htm