New research looks to examine European corn borer resistance to Bt crop technology – Agweek
ST. PAUL, Minn. — While European corn borer once caused substantial yield losses and economic damage for corn growers across the United States, the pest has not been a major cause of concern since Bt technology was introduced as an effective strategy in mitigating the pest in the 1990s.
However, in recent years, the pest has begun to develop a resistance to Bacillus thuringiensis crops. In 2021, European corn borer alone was responsible for the losses of approximately 338,000 bushels of corn in the U.S., according to the University of Minnesota.
Nick Wagner / The Forum
Fei Yang, assistant professor and Extension entomologist for the University of Minnesota, said the first case of European corn borer resistance to Cry1F Bt corn was discovered in Nova Scotia in Canada in 2018. Since then, resistant European corn borer has expanded to Quebec and Manitoba.
An expanding resistance poses much risk for U.S. corn growers. In 2023, a field of Bt sweet corn producing Cry1A.105 and Cry2Ab2 proteins in Connecticut experienced significant damage from ECB infestation. In addition, a conventional field corn in Crookston, Minnesota, was found to be heavily infested with European corn borer larvae in 2023, with around 30-35% of 1,000 surveyed plants exhibiting damage, a clear indication of an European corn borer “hot spot” in the field.
Yang, along with other University of Minnesota researchers, are looking to monitor the issue for U.S. corn growers with research funded by the Minnesota Corn Growers Association, and the Minnesota Corn Research and Promotion Council.
Contributed / University of Minnesota
“It seems like we don’t have any other technologies right now for management of European corn borer,” Yang said. “Once the insects develop resistance to both of these two groups of Bt proteins, the populations may come back, because resistance can spread very fast if we don’t have any good control strategies.”
Their research focuses on examining populations of European corn borer from different locations in Minnesota and neighboring locations in South Dakota and North Dakota.
“They can fly long distances. So even the population we found in Minnesota, sometimes they can travel to Wisconsin, South Dakota, North Dakota, and also those populations in the neighboring states can also fly to Minnesota,” Yang said.
After collecting the populations, an F2 screening was then conducted to isolate resistance alleles, or resistance genes, from the field population. Research showed that populations in both Minnesota and Wisconsin showed moderate resistance to Cry1F Bt crops.
“The Bt technology for resistance management is ineffective, causing the fast evolution of European corn borer resistance to the Bt hybrids on the market,” Yang said.
The next step of the research will be documenting the resistance to the Cry2 Bt protein to have a better understanding of the genetic basis of the resistance.
“After understanding the genetic basis, we can evaluate the risks of resistance to this protein and also the cross resistance to other Bt proteins,” Yang said.
According to the University, implementing integrated pest management practices is crucial in targeting the pest. Implementing conservation-focused practices as well as plowing corn plant residue to a depth of at least 8 inches and shredding corn stalks can also aid in the prevention of resistance.
The University of Minnesota advises anyone that has identified European corn borer infestations in their field to reach out to them so they can help in determining the Bt resistance levels of these insects.
Kennedy is a reporter for Agweek based out of South Dakota. She grew up on an organic crop farm where her family also raises cattle in eastern South Dakota. She graduated from South Dakota State University in 2023 with a major in agricultural communication and minor in agricultural business. She enjoys connecting with producers and agribusinesses across the region while reporting on all things agriculture.
