Prospects for importation biological control of the soybean aphid: Anticipating potential costs and benefits

We discuss the potential pros and cons of using importation biological control against the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae). Importation of exotic organisms for biological control is never completely risk-free, but the potential negative impacts of not achieving biological control of invasive pests may exceed the risks associated with a biological control introduction. The potential benefits of biological control include reduced insecticide use and a reduced ability of the invasive pest to impact native flora and fauna, and we outline what the scope of these benefits may be for the soybean aphid. The benefits are only accrued, however, if biological control is successful, so the likelihood of successful biological must also be assessed. Accordingly, we outline some issues relevant to predicting the success of importation biological control of the soybean aphid. We also outline the potential risks to nontarget organisms that would be associated with importation biological control of the soybean aphid. Currently, two parasitoid species, Aphelinus albipodus Hayat and Fatima (Hymenoptera: Aphelinidae) and Lipolexis gracilis Förster (Hymenoptera: Braconidae) have been imported from Asia and have passed through quarantine. We briefly review the biology and host range of these two species. A different strain of A. albipodus that was released against the Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), in the early 1990s was also found to attack the soybean aphid in the laboratory and has been redistributed from Wyoming to Minnesota and Wisconsin in field releases against the soybean aphid. We discuss our rationale for going forward with this redistribution.