Resistance to Aphis glycines (Hemiptera: Aphididae) in various soybean lines under controlled laboratory conditions.

The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), a pest of soybean, Glycine max (L.) Merr., native to Asia, has recently become a principal pest of this crop in many areas of North America. Insecticides are currently used to manage A. glycines, but host plant resistance is a potential alternative management tool. Tests were conducted to determine resistance to A. glycines among soybean lines. 'Cobb,' 'Tie-feng 8,' and 'Jackson' were resistant to population growth of A. glycines compared with 'Cook' and '91B91,' a susceptible control. Antibiosis was evident in Cobb, Jackson, and Tie-feng 8 from lowered survival of first generation A. glycines, and in Cobb, Jackson, Tie-feng 8, and 'Braxton' from diminished reproduction by first generation aphids. Antixenosis was apparent in Cobb and Jackson during initial infestation of aphid population growth tests, because A. glycines were unsettled and dispersed readily from placement points on unifoliolate leaves. Decreased nymphiposition by A. glycines occurred on Cobb and Jackson, and it may have been caused by antibiotic chemicals in these lines, failure of aphids to settle, or both. Differences in distribution of A. glycines between unifoliolate leaves and other shoot structures suggest that unifoliolate leaves were acceptable feeding sites on 91B91 and Cook, whereas unifoliolate leaves and other shoot structures were roughly equally acceptable feeding sites on Braxton, Tie-feng 8, Jackson, and Cobb. However, Jackson and Cobb had relatively low counts of A. glycines on shoots that may have been due to abandonment of plants by aphids, decreased aphid survival, or both. Results confirm earlier findings that Jackson is a strong source of resistance to A. glycines, and they suggest that Tie-feng 8, Braxton, and especially Cobb are potentially useful sources of resistance.