Border vegetation alters Kentucky soybean pest immigration and subsequent movements

Soybean fields are sometimes bordered by a variety of vegetation types, but are typically unmanaged. The maintenance of these habitats as non-crop vegetation potentially reduces chemical input required within crop fields by providing alternative pest management opportunities. These border areas can be used to supplement predator populations as well as providing a trap crop area for important Kentucky soybean pests.

This research quantifies how border vegetation surrounding soybean fields influences pest immigration rates, examines the directional spread of pests, and characterizes the within-field distribution of insect pests. Field border vegetation was characterized based on composition and foliar density and subsequently divided into generalized categories (i.e. weeds, trees, soybean, and corn). Samples were collected using hand sampling and sweep net sampling from Kentucky soybean fields. The GPS coordinate of each sample was taken and used for SADIE (Spatial Analysis by Distance IndicEs) analysis. These spatial analyses were used as indicators of population clusters and interactions between pest and edge resources over time and space. The resulting data indicated that soybean pest densities increased in fields with edges of soybeans and grass/weeds; however, each pest species differed in relation to these edge types. For instance, Japanese beetle and grasshopper populations were lower in fields with tree/shrub edges, but these same edges increased the abundance of stinkbugs and three-cornered leafhoppers. These results indicate that edge vegetation could be managed to provide valuable biological control services of pests in soybean.