Identification and characterization of new sources of resistance to Aphis glycines Matsumura (Hemiptera: Aphididae) in soybean lines

The soybean aphid, Aphis glycines Matsumura, is a pest of soybean [Glycine max L. (Merrill)] in Asia, and its recent establishment in North America has led to large, recurring outbreaks that have challenged pest management practitioners to seek environmentally responsible means for its control. Growth-chamber experiments identified resistance to A. glycines in soybean lines 'Perrin'; 'Tracy-M,' its glabrous near-isoline 'D88-5328,' and its densely pubescent near-isoline 'D88-5272'; 'D75-10169,' its glabrous near-isoline 'D90-9216,' and a densely pubescent near-isoline 'D90-9220.' Tracy-M and D75-10169 were antixenotic to A. glycines in host-selection tests. In no-choice nymphiposition tests, the number of nymphs deposited by A. glycines on D75-10169, Perrin, and Tracy-M did not differ from that on other lines after 24- and 48-h test periods. Under conditions in which A. glycines were free to distribute on plants over a 48-h period, aphids were found primarily on stems and trifoliolate leaves of Perrin, Tracy-M, D75-10169 and a resistant control, 'Dowling,' whereas the majority of aphids infesting susceptible lines '91B91' and 'Davis' were distributed on unifoliolate leaves. Irrespective of shoot structure, low numbers of A. glycines were found on Dowling compared to other lines. The mean number of days to reproductive maturity for A. glycines did not differ among lines. Aphis glycines produced fewer nymphs during the first 7d of reproduction on Perrin, Tracy-M, D75-10169 and Dowling compared to Davis, and fewer A. glycines progeny were produced on D75-10169 and Dowling than on 91B91. Results show that Dowling continues to be a strong source of resistance to A. glycines. Perrin, Tracy-M, and D75-10169 have been used as sources of resistance to other insects, and discovery of resistance to A. glycines in these three lines may increase their utility in soybean breeding programs.