Wisconsin soybean aphids (Aphis glycines): molecular characterization and comparison with known biotypes

Soybean is the world’s foremost provider of protein and oil. Since introduction to the U.S. in 2000, the soybean aphid has become soybean’s most significant insect pest. Attention has shifted away from quick-fix, environmentally hazardous insecticides toward the more robust, sustainable management strategy: plant resistance. While several resistance genes are in the pipeline, current aphid-resistant soybean varieties rely on a single gene, Rag1, to confer resistance. The emergence of resistance-defeating soybean aphid biotypes poses a significant and perplexing challenge to the success of plant resistance. Toward the goal of discovering how soybean aphids defeat resistant soybean, efforts are currently underway to differentiate and characterize the distribution of soybean aphid biotypes using molecular tools. Soybean aphid populations in Wisconsin are able to colonize Rag1 and Rag2 soybean to a certain extent, suggesting some degree of differentiation from the described biotypes 1, 2 and 3. Soybean aphids will be collected from aphid-susceptible and -resistant soybean fields around Wisconsin and characterized by choice test and SNP detection assays. Results will be presented and compared with those from other states currently being surveyed, and implications to soybean growers will be discussed.