Potential non-target impacts in prairies from biological control of the soybean aphid

The soybean aphid, Aphis glycines Matsumura, is a major pest of Midwest soybean production, and classical biological control is being attempted throughout the region to help manage this exotic pest. Concerns over non-target effects from an introduced natural enemy prompted an investigation of the risk of non-target effects on the prairie aphid-parasitoid community in Indiana. Pre-release studies of aphids and associated parasitoids were conducted at six Indiana prairies in 2006-07. Transect sampling was used to collect information on the aphids, their host plants, and parasitoids. Host plant abundance, aphid species richness and diversity, and parasitoid species richness and diversity information was obtained for each site in both sampling years. Results indicate that a dynamic aphid-parasitoid community exists in the Indiana prairies. Aphid abundance and species richness of aphids and parasitoids varied widely on both spatial and temporal scales. Overall 67 aphid species and 10 primary parasitoid species were found during the 2-year survey. The fluctuating composition of the aphid-parasitoid community may indicate the ability of the community to withstand non-target effects from the introduction of a soybean aphid biological control agent.