Effects on survival of Nabis spp. fed diets of soybean aphid from resistant and seed-treated soybean

Minnesota’s native nabids, (Nabis spp)., a general predator of soft-bodied insects, are natural enemies of the invasive soybean aphid, (Aphis glycines Matsumura). Since 2000, several soybean management methods have been studied in order to reduce soybean aphid crop damage. These methods include chemical, biological and most recently, resistant and insecticide seed-treated soybean. Although these treatments seem to improve soybean aphid management, it is sometimes unclear whether there are non-target effects of these treatments on natural enemies of the soybean aphid. For this study we looked at one natural enemy of the soybean aphid, the nabid. The purpose of this study was to: 1) determine if nabids can survive on a diet of soybean aphid and 2) determine and compare nabid survival rates on Rag1 resistant, seed-treated, and susceptible soybean plants. The four soybean treatments included: untreated susceptible, seed-treated susceptible, untreated Rag1 resistant, and seed-treated Rag1 resistant soybean. Laboratory-reared nabid nymphs were placed individually on an excised soybean leaf in a Petri dish and fed soybean aphids until death. The results of this experiment showed that nabids can survive on a diet of soybean aphid, and those feeding on untreated soybean, whether Rag1 resistant or susceptible, saw on average, a 30% longer lifespan than those feeding on seed-treated soybean. This study demonstrates that management methods for the invasive soybean aphid can have negative effects on the natural enemy community.