**Submitted to:** Euphytica

**Publication Type:** Peer Reviewed Journal

**Publication Acceptance Date:** 9/11/2006

**Publication Date:** 10/20/2006

**Citation:** Hesler, L.S., Dashiell, K.E., Lundgren, J.G. 2006. Characterization of resistance to aphis glycines in soybean accessions. Euphytica. 154:91-99.

**Interpretive Summary:** Growth-chamber experiments were conducted to determine and characterize host-plant resistance to the soybean aphid (SBA), a pest of soybean in Asia and North America. Soybean lines were screened for resistance by rating SBA-population growth in two tests. All Dowling and PI 230977 plants and 25 percent of PI 71506 plants were rated as resistant to aphids (fewer than 100 aphids per plant) in the first test. Dowling, PI 71506 and PI 230977 were resistant (fewer than 150 aphids per plant), and 50 percent of plants of line G93-9223 were resistant in the second test. Distribution of SBA on host plants differed markedly among lines after initial infestation on unifoliate leaves. Large numbers of SBA were found on 91B91 and Ripley, with aphids distributed mostly on unifoliate leaves. Intermediate numbers of SBA were found on PI 71506 and G93-9223, and SBA were roughly evenly distributed over plants of these two lines. Low numbers of SBA were found on Dowling and PI 230977, mainly on shoot structures other than unifoliate leaves. In a no-choice test, SBA deposited fewer nymphs over 24 h on Dowling and PI 230977 than on 91B91, G93-9223, and Ripley. A second test showed that SBA deposited fewer nymphs on Dowling, PI 71506 and PI 230977 than on 91B91 and Ripley. Fewer SBA reached reproductive maturity on PI 230977 than on 91B91, Ripley, G93-9223 and PI 71506. Proportion of aphids that matured on Dowling was low but did not differ from that on other lines. Days for SBA to mature did not differ among lines. Over 7 days, SBA produced fewer progeny on PI 230977 and Dowling than on 91B91, PI 71506 and Ripley. Dowling and PI 230977 demonstrated modalities of non-preference and antibiosis to SBA, and PI 71506 and G93-9223 were antixenotic. These accessions may be valuable sources to breed for resistance to SBA.

**Technical Abstract:** Growth-chamber experiments were conducted to determine and characterize host-plant resistance to the soybean aphid, Aphis glycines Matsumura, a pest of soybean (Glycine max L. (Merrill)) in Asia and North America. Soybean accessions were screened for resistance by rating A. glycines-population growth in two tests. All ‘Dowling’ and PI 230977 plants and 25 percent of PI 71506 plants were resistant (<100 aphids per plant) in the first test. Dowling, PI 71506 and PI 230977 were resistant (<150 aphids per plant), and 50 percent of plants of line ‘G93-9223’ were resistant in the second test. Distribution of A. glycines on host plants differed markedly among accessions after initial infestation on unifoliate leaves. Large numbers of A. glycines found on ‘91B91’ and ‘Ripley’ were distributed mostly on unifoliate leaves. Intermediate numbers of A. glycines were roughly evenly distributed on plants of PI 71506 and G93-9223. Low numbers of A. glycines were found on Dowling and PI 230977, mainly on shoot structures other than unifoliate leaves. In a no-choice test, A. glycines deposited fewer nymphs over 24 h on Dowling and PI 230977 than on 91B91, G93-9223 and Ripley. A second, 48-h test showed that A. glycines deposited fewer nymphs on Dowling, PI 71506 and PI 230977 than on 91B91 and Ripley. Fewer A. glycines reached reproductive maturity on PI 230977 than on 91B91, Ripley, G93-9223 and PI 71506. The proportion of aphids that matured on Dowling was low but did not differ from that on other accessions. Days for A. glycines to mature did not differ among accessions. Aphis glycines produced fewer progeny over 7 d on PI 230977 and Dowling than on 91B91, PI 71506 and Ripley. Thus, Dowling and PI 230977 demonstrated antixenosis and antibiosis to A. glycines, and PI 71506 and G93-9223 were antixenotic. These accessions may be valuable sources to breed for resistance to A. glycines.