Extended Abstract (100K)10A.2
Soybean aphids aloft: spread of an exotic pest through the upper Midwest
Robert C. Venette, University of Minnesota, St. Paul, MN; and D. W. Ragsdale
Soybean aphid, Aphis glycines Matsumura, is a native pest of soybean in eastern Asia and was first detected in the United States in 2000. At the end of the 2000 growing season, soybean aphid was reported in Minnesota, Wisconsin, Michigan, Iowa, Missouri, Illinois, Indiana, Ohio, Kentucky, and West Virginia. During 2001, we collected a number of field observations to evaluate overwintering capacity and dispersal potential in Minnesota with the intent of better characterizing risks associated with this new pest. The primary host for the aphid, Rhamnus spp., occurs commonly within the region and created an opportunity for local overwintering. In 2001, rapid colonization of early-vegetative (V1 growth stage) soybean, Glycine max, provided evidence of winter survival, at least in localized areas. From June to September, 1,700 soybean fields throughout Minnesota were monitored for the presence of the aphid. Locations of fields with and without aphids were noted with GPS units. Range expansion over time was measured using minimum convex polygon, kernel home range, and average expanding radii. A series of suction traps were also maintained to detect aphid flight. Aphids were first detected in soybean fields on June 12 in Houston County (SE corner of Minnesota). During the 2001 growing season, we estimated that soybean aphid spread to the west/northwest at an average rate of 40.7 to 60.2 km per week (25.2 to 37.4 mi per week). Rate of spread was not constant throughout the year. Three distinct phases were evident: moderate spread (late June), slow spread (early-mid July), and rapid spread (late July to mid-August). Soybean aphids were first detected in suction traps on July 30. Periods of rapid aphid dispersal correspond to peak periods of alate activity. Aphid dispersal appears to have been facilitated by winds at the surface boundary layer. Studies of overwintering habitats and dispersal are planned for 2002 and will be discussed.
Session 10A, Aerobiology: Insects
Wednesday, 30 October 2002, 2:45 PM-4:15 PM
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