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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY BASED PEST MANAGEMENT IN MODERN CROPPING SYSTEMS

Location: North Central Agricultural Research Laboratory

Title: Field evaluation of putatively resistant soybean selections against the soybean aphid

Authors
item Hesler, Louis
item Dashiell, Kenton -
item Prischmann, Deirdre -
item Diers, Brian -
item Scott, Roy

Submitted to: Journal of Crop Improvement
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 2011
Publication Date: January 17, 2012
Citation: Hesler, L.S., Dashiell, K.E., Prischmann, D.A., Diers, B.W., Scott, R.A. 2012. Field evaluation of putatively resistant soybean selections against the soybean aphid. Journal of Crop Improvement. 26:76-78.

Interpretive Summary: The soybean aphid is a serious pest of soybean in North America, and the use of soybean lines that are resistant to the aphid is one potential means to manage this pest. Field-testing of soybean lines is a critical step in confirming resistance, and the objective of the current study was to evaluate resistance to soybean aphid under field conditions using the various soybean selections derived from a known aphid-resistant soybean line. Various soybean selections with the aphid-resistance gene for Rag1 were evaluated among soybean selections without Rag1 and among contemporary soybean lines in a two-year field test. Overall, aphid levels per plant were over 10-fold greater in 2006 than in 2005, but lines generally performed similarly relative to one another between years with respect to aphid-infestation levels. In both years, several selections predicted to have the resistance gene had the lowest mean number of soybean aphids per plant. However, in 2005, three selections predicted to have Rag1 had intermediate aphid infestation levels that were greater than those of other Rag1 selections, and in 2006 two of those selections also had intermediate aphid levels that did not differ from all other lines. Irrespective of the resistance gene, all soybean lines tested in 2006 had potentially injurious infestations of soybean aphids that exceed action thresholds for this pest. These results show varying levels of resistance among putatively resistant soybean lines and that protection may be equivocal in years of heavy infestation by soybean aphid. Implications for testing reputedly aphid-resistant soybean selections in the field and the potential for field-deployment of aphid-resistant lines are discussed.

Technical Abstract: The soybean aphid, Aphis glycines Matsumura, has become a serious pest of soybean in North America, and host-plant resistance is one potential management tool. In the current study, various F2-derived soybean selections with the Rag1 gene for resistance to soybean aphid were evaluated among F2-derived soybean selections without Rag1 and among contemporary soybean lines in a two-year field test. Overall, aphid levels per plant were over 10-fold greater in 2006 than in 2005, but lines generally performed similarly relative to one another between years with regard to aphid-infestation levels. In both years, the Rag1 selections ILL4, ILL27, ILL35, ILL37, ILL64RR, ILL76RR, and ILL77RR that contained Rag1 had the lowest mean number of soybean aphids per plant. However, in 2005, three selections putatively with Rag1--ILL26, ILL67RR and ILL87--had intermediate aphid infestation levels that were greater than those of other Rag1 selections, and in 2006 ILL26 and ILL67RR also had intermediate aphid levels that did not differ from all other lines. Irrespective of the Rag1 gene, all soybean lines tested in 2006 had potentially injurious infestations (means greater than 799 soybean aphids per plant) that exceed action thresholds for this pest. These results show varying levels of resistance among lines that are homozygous for the Rag1 resistance allele and that protection may be equivocal in years of heavy infestation by soybean aphid. Implications for testing putatively aphid-resistant soybean selections in the field and the potential for field-deployment of aphid-resistant lines are discussed.

Last Modified: 12/22/2014