Local and regional approaches to studying the phenology and biological control of the soybean aphid
Soybean aphids Aphis glycines Matsumura (Hemiptera: Aphididae) are an economic pest of soybean Glycine max (L.) Merr. in much of the United States and parts of Canada. Some crucial phenological information of A. glycines is unknown, specifically source-sink dynamics between and within host plants and factors guiding aphid migrations. In addition, there are discrepancies in the literature on the importance of food webs and how local landscape effects can alter A. glycines populations. Increasing our understanding of A. glycines population dynamics may improve predictions of aphid outbreaks and integrated pest management efforts. The first objective was to determine how landscape composition and heterogeneity impact A. glycines and their natural predator community. This study was centered in and around the Neal Smith National Wildlife Refuge located in Jasper County, Iowa. A second objective was to determine how prairie plantings adjacent to soybean impact A. glycines and natural enemy populations. To accomplish this, four study sites in central Iowa, transects were established up to 200 m in both soybean and prairie. A third objective was to describe A. glycines movement patterns on a regional scale. We monitored winged aphids (alates) using a suction trap network established at 42 locations over 10 states. Alates where correlated with northern latitudes which led to the last objective which was to predict A. glycines using low temperature data from the Midwest US and determine whether temperatures have reached A. glycines supercooling point (-34oC).