2010 Annual Report 1a.Objectives (from AD-416) Rear and test host specificity of Asian parasitoids that are candidates for biological control of the soybean aphid. 1b.Approach (from AD-416) Rear imported parasitoid species in quarantine. Expose them to a range of aphid species to determine which ones they are capable of attacking under laboratory conditions. Draw inferences about potential host range after introduction against soybean aphid. 3.Progress Report Since soybean aphid was accidentally introduced into the US around 2001, it has become the major pest of soybean. To find biological control agents to introduce against soybean aphid, we have imported and reared in quarantine 46 populations of soybean aphid parasitoids in at least 15 species from China, Japan, and Korea during the last 8 years; 4 new populations were imported in 2010. We have evaluated host specificity of 28 populations; 24 had broad host ranges and have been eliminated from consideration. Three species were previously found to have narrow host ranges. This year another species new to science, APHELINUS near ENGAEUS from Xiyuan, China, was found to have a narrow host range. This parasitoid readily accepts and survives well in soybean aphid, but survives much less well in other aphids in the genus APHIS, and hardly recognizes aphids in other genera. These results support the safety of introducing this parasitoid to control soybean aphid. Establishment of this parasitoid should significantly reduce abundance of soybean aphid and thus damage and control costs. Monitoring was achieved through telephone calls, written quarterly reports, emails, and conference calls.