Determining the effectiveness of three-gene pyramids against soybean aphid biotypes

Project Type: Research and Education
Funds awarded in 2015: $127,247.00
Projected End Date: 09/30/2019
Grant Recipient: Iowa State University
Region: North Central
State: Iowa
Project Coordinator:
Erin Hodgson
Iowa State University
Since the discovery of Aphis glycines Matsumura (Hemiptera: Aphididae) in the United States, the primary management tactic has been foliar insecticides. Alternative management options such as host plant resistance to A. glycines have been developed and their effectiveness proved. However, the use of host plant resistance was complicated by the discovery of multiple, virulent biotypes of A. glycines in the United States that are capable of overcoming single Rag genes, Rag1 and Rag2, as well as a two-gene pyramid of Rag1+Rag2. However, current models predict that the virulent allele frequency of A. glycines decreases in response to the use of pyramided Rag genes, suggesting that pyramids represent a more sustainable use of these traits. Previous research has demonstrated that virulent biotypes can be effectively managed using a three-gene pyramid of Rag1+Rag2+Rag3. Additional Rag-genes have been discovered (Rag4 and Rag5), but whether the incorporation of these genes into novel three-gene pyramids will improve efficacy is not known. We tested single-gene (Rag1 and Rag2) and pyramid cultivars (Rag1+Rag2, Rag1+Rag2+Rag3, Rag1+Rag2+Rag4) to multiple biotypes in laboratory assays. Our results confirm that the Rag1+Rag2+Rag3 pyramid effectively manages all known A. glycines biotypes when compared with cultivars that are overcome by the associated biotype. Our results indicate that Rag1+Rag2+Rag4 would be an effective management option for biotype-1, biotype-2, and biotype-3 A. glycines, but had a negligible impact on biotype-4.
Peer-reviewed Journal Article
Adam Varenhorst
Shelby Pritchard
Matt O'Neal, Iowa State University
Erin Hodgson, Iowa State University
A. K. Singh, Iowa State University
This product is associated with the project "Protecting Soybeans from Aphids, as Easy as (Rag) 1, 2, and 3"
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.