Determining the source of soybean aphid (Aphis glycines) populations in Pennsylvania

Aphis glycines is an important pest of soybean as well as a competent virus vector in other legumes. In order to better understand the origin of soybean aphid in Pennsylvania, we used microsatellite markers to investigate its population structure. We looked at temporal change in allele frequency by collecting aphids from soybean at weekly intervals during the summer from an unsprayed sentinel field in central Pennsylvania. Aphids from early August in Pennsylvania were compared to those collected close to the same time from soybean in New York, Virginia, and Ohio to identify any spatial differences in allele frequency. When samples from Pennsylvania matched those in other geographic regions, we used HYSPLIT to determine if any weather systems could have been responsible for their immigration. This information will further our understanding of aphid movement to states that do not have a strong local population.