Since their discovery in Wisconsin in 2000, soybean aphids quickly became a yield-robbing pest that farmers contend with nearly every year. Though infestation levels vary from year to year, their very presence warrants regular scouting to determine if farmers need to take action.
Research supported by 12 state soy checkoff boards through the North Central Soybean Research Program (NCSRP) involves 28 scientists at 12 land-grant universities and covers a broad range of research topics related to soybean aphid biology and management. NCSRP projects include:
- Breeding and field performance of aphid-resistant varieties
- Discovery of aphid-resistance traits
- Aphids that can overcome resistant varieties
- The economic returns on insecticidal seed treatments and other management approaches
- How to maximize the impact of beneficial predatory insects that eat soybean aphids
“The desired outcome of our work is to increase profitability and sustainability for soybean farmers and to provide unbiased information to help them with their management decisions,” said Kelley Tilmon, associate professor and soybean extension specialist at South Dakota State University. “Checkoff programs serve a vital role by funding unbiased public-sector research that wouldn’t get conducted elsewhere.”
The research shows that aphid-resistant varieties hold tremendous potential for aphid management. Tilmon says researchers found that two aphid-resistant genes, called Rag1 and Rag2, which stand for ”resistant to aphis glycines,” when applied together in a gene pyramid, perform as well or better than insecticides, virtually eliminating aphids from the field.
The Rag1 and Rag2 genes each provide good aphid management, but there are a number of aphids that can overcome them individually. In a heavy aphid year, spray-worthy populations can still develop. By putting the two genes together, farmers get a one-two punch.
“I think it could be a game changer for aphid management,” Tilmon stated. “There are several other genes in the pipeline, so triple pyramids are possible too. There’s no reason these varieties can’t be high agronomic performers.”
Varieties with the Rag genes are commercially available on a limited scale, mostly from smaller seed suppliers and university foundation sources.
Tilmon cautions that though the genetic research is promising, it should be viewed as another tool in the toolbox for battling aphids.
“We all know there’s no such thing as a silver bullet,” she added. “The appearance of Bt-resistant corn rootworm populations is a reminder about that for all of us, but with good management tactics, we can extend the utility of these tools for a long time to come.”