New plant introductions with resistance to the soybean aphid

The soybean aphid (SA; Aphis glycines Matsumura) was first found in the northern soybean [Glycine max (L.) Merr.] growing regions of the United States in 2000. By 2005, the aphids had spread to 23 soybean growing states reaching as far south as Mississippi and Georgia and also north into Ontario, Canada. The objective of this study was to identify new sources of resistance to the SA. Nearly 200 soybean genotypes (cultivars, breeding lines, and plant introductions [Pis]) were screened for resistance to SA in a greenhouse choice test using SA collected in Wooster, OR Three Pis (PI 243540, PI 567301B, and PI 567324) were identified as resistant while six Pis were identified as moderately resistant. The findings on the three resistant and three of the six moderately resistant Pis were confirmed through further field and greenhouse tests. PI 243540 displayed strong antibiosis resistance such that SA was unable to survive on this PI in a no-choice test. The other two resistant PIs possessed mainly antixenosis type resistance. PI 243540 and PI 567301 B were also resistant to the SA collection from Illinois. The aphid resistant Pis identified in this study will be useful in efforts to develop aphid-resistant soybean cultivars.