Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2003
Publication Date: 2/1/2004
Citation: Hill, C.B., Li, Y., Hartman, G.L. 2004. First report of resistance to the soybean aphid in soybean germplasm. Crop Science; 2004
Interpretive Summary: In 2000, the soybean aphid was discovered in North America from Asia, posing a new threat to soybean production. Resistance to the aphid was unknown and a project to identify resistance in soybean germplasm began in 2001. Over 1,600 soybean cultivars and germplasm accessions were screened for resistance to the soybean aphid using an efficient greenhouse screening method. Resistance was found in nine soybean lines. These resistance sources will be used to develop soybean cultivars resistant to the soybean aphid. This research is important to both commercial and public soybean breeders as well as researchers interested in insect resistance in plants.
Technical Abstract: Using an efficient greenhouse screening method, the first resistance to the soybean aphid (Aphis glycines Matsumara) was found in soybeans [Glycine max (L.) Merr.]. Resistance was not found in 1346 MG II-IV cultivars, 106 MG 000-VII Asian cultivars, 79 MG V-VIII cultivars, and in a set of 11 Clark iso lines possessing different pubescence traits. Resistance was established in three ancestors of North American cultivars: Dowling, Jackson, and PI 71506. Expression of resistance in those cultivars was characterized in choice and non choice tests. In choice tests, significantly fewer aphids occurred on Dowling, Jackson, and PI 71506 plants compared to susceptible cultivars (P = 0.05). Aphid populations did not develop on Dowling and Jackson in non choice tests, indicating that there was a negative impact on aphid fecundity on those cultivars and that evidence combined with observations of aphid mortality on those cultivars suggested that antibiosis type resistance contributed to expression of resistance. Possible donors of resistance to Dowling and Jackson were identified. Population development on PI 71506 was not significantly different from development on susceptible cultivars, indicating that antixenosis was more important in that cultivar. Resistance was expressed in all plant stages in the greenhouse and field. Dowling provided season long protection against aphids equal to the use of the systemic insecticide imidacloprid in a field test. Four other lines: Sugao Zarai, Sato, T260H, and PI 230977 had levels of resistance not significantly different from Dowling, Jackson, and PI 71506 in a choice test (P = 0.05). Dense pubescence did not provide protection against the soybean aphid.