Expert research team provides aphid tolerance scores, continues research
DES MOINES, Iowa, Soybean aphids plagued many fields across the United States U.S. this season, leaving growers to find more effective management strategies for next year. According to researchers at Pioneer Hi-Bred, a DuPont business, growers can choose varieties based on aphid resistance – or antibiosis – scores. This is thanks to a designated Pioneer research team that evaluates aphid antibiosis and continues to improve aphid resistance in soybean varieties.
Pioneer researchers score soybean varieties by the plant’s antibiosis properties, or inherent characteristics that discourage aphids from feeding and reproducing. Researchers score soybean varieties exceptional (E), above average (AA), average (A) and below average (BA) which allows growers to prioritize field scouting and insecticide application.
Scouting for aphids is a common way to detect aphid infestations, a practice Jessie Alt, Pioneer research scientist, and fellow researchers promote.
“Pioneer is helping growers prioritize scouting by providing these antibiosis ratings,” Alt says. “Varieties with below-average antibiosis scores need to be managed differently than those with above-average scores. It’s important to keep a close check on field conditions because aphids can cause damage rapidly. If left untreated, aphids can destroy 50 percent of the potential yield.”
First appearing in the Great Lakes area in 2000, aphids quickly have become a major soybean pest in North America, spanning to almost all soybean-growing areas in the U.S. and Canada. In recent years, aphids are no longer an every-other-year issue, but instead can be a significant yield-robbing pest any season.
Currently, the most effective management strategies include selecting soybean varieties with native antibiosis and timely application of insecticides.
“Aphids are a major issue right now, so we’re addressing the problem with a special soybean team comprised of breeders, research scientists and an entomologist,” Alt says. “We conduct controlled screenings to develop stronger antibiosis scores in different soybean varieties.”
Pioneer research teams expect to unveil new products with improved soybean antibiosis scores that incorporate the best new or novel genes conferring resistance. The level of resistance acts as a type of insurance to growers by protecting their crop from this pest while reducing the number of insecticide applications, Alt says.
“Growers can manage soybean aphids by planting resistant soybeans as the first line of defense,” she says. “And they can back that up with insecticide applications if necessary.” To find resistance to multiple aphid biotypes, Pioneer researchers draw from many different sources.
“Our research includes screening multiple areas to give us a broad idea of how Pioneer varieties will respond to soybean aphids,” Alt says. “We screen aphid collections from several different sites around the Midwest. For example, aphids in Indiana or Ohio may behave differently than those in South Dakota. Having multiple research sites throughout North America is a significant benefit to help us determine which products work best in specific soybean-growing areas.”
Antibiosis research involves trapping aphids into the sticky cages on leaves of the soybean then observing whether the insects can reproduce or colonize. The Pioneer research team performs various testing in controlled growth centers.
“Our research shows the Pioneer antibiosis rating system is working,” Alt says. “We test soybean varieties for their aphid tolerance level in fields ranging from those treated with varied levels of insecticide to untreated fields. It’s evident how devastating aphid damage can be on fields of varieties with low tolerance to aphids.”
Moving forward, growers likely will see continued improvements in the area of soybean aphid antibiosis as well as resistant varieties.
“There’s a lot of research being done with resistant lines,” Alt says. “We’re stacking genes to create a higher level of resistance in the future. On-farm product advancement trials in 2010 will continue to help us determine what’s working best.”