Soybean aphid, Aphis glycines Matsumura, was first discovered in the United States in August 2000. This study was initiated to determine if the aphid could overwinter in Minnesota and to determine when and how it colonizes soybean. Although the aphid was not observed on its putative overwintering host, Rhamnus cathartica, indirect evidence suggests A. glycines was able to overwinter in 2001. Soybean aphid was first found on V1 soybeans on 12 June 2001 in Houston County in southeastern Minnesota. By the end of June 2001, soybean aphid was found in six counties in southern Minnesota. These initial surveys reveal no consistent preference for various row spacings, date of planting, plant variety, or soil type. However, soybean fields adjacent to wooded areas with buckthorn, were more likely to be infested with A. glycines. Generally, soybean fields in Houston County, where soybean aphid caused significant damage in 2000, had the highest prevalence with 10 - 15% of plants infested with an average of 11 apterae/plant. Counties further north had fewer fields with aphids and prevalence was 10% with an average of 8 aphids per plant. We chose two, 15-acre fields in Houston County with soybean aphid to repeatedly sample throughout the growing season. Our objective was to determine the initial colonization pattern, the within-field distribution of soybean aphid, and to identify mortality factors of the aphid. We used Geographic Information Systems and Global Positioning Systems to design a regularly spaced point pattern. Ten plants were randomly selected near each point (80 points per field) and assessed for presence of soybean aphid, parasitized aphids, soybean aphid density, and occurrence of alatae and alatoid nymphs. Predators were sampled using a sweepnet taking ten 50-sweep samples randomly throughout the field.
Species 1: Homoptera Aphididae Aphis glycines (soybean aphid)
Keywords: distribution
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA