Soybean aphid migrations across the midwestern United States: a summary of the suction trap network

The soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae) is an economically important pest in soybean Glycine max (L.) Merr. in the U.S. Biological information of A. glycines is limited and pest outbreaks persist in soybean throughout the Midwest. For example, little is known about factors guiding migrating aphids and potential impacts of long distance immigration. Increasing our understanding of A. glycines population dynamics would improve our ability to predict aphid outbreaks. In 2005 a suction trap network was established in seven states within the Midwest to monitor aphid movements. By 2006 this network expanded to 10 states and consists of 42 traps. The goal of the suction trap network is to monitor aphid movement; specifically aphids leaving their overwintering host Rhamnus spp. for soybean during the spring, aphids moving from soybean to soybean during the summer, and aphids leaving soybean for Rhamnus spp. in the fall. Objectives of this study are to summarize the occurrence of alates from the suction trap network between 2004 and 2008. Overall, alate A. glycines are not readily collected in suction traps until June. Peak catches occur at most locations in late July to mid August. Regression analyses between alates and geographic coordinates suggest an East to West migration explains little of the variation in alate catch; however, a North to South trend explains more of these data. Spatial and temporal analyses significantly vary by date and year. In general spatial association between sites is smaller during summer movements than fall.