Widespreed planting of genetically modified Bt corn in the upper Midwest has significantly reduced losses from European corn borer damage. Even growers that don’t plant transgenic corn have benefitted from neighboring use of these products.
The total economic benefit of Bt corn’s pest suppression in five Midwestern states between 1996 and 2009 totaled $6.9 billion. Yet when researchers looked at the data based on product usage, they found 62% of the economic benefit was gained in fields where non-Bt corn hybrids had not planted.
Thanks to Bt corn hybrids, corn borer numbers have dropped 28% to 73% in neighboring non-Bt fields in Minnesota, Illinois and Wisconsin. Smaller declines have occurred in Iowa and Nebraska.
Gain From Others
In Wisconsin alone, 75% of the state’s total economic benefit from Bt corn’s pest suppression has been earned by growers who do not plant transgenic hybrids.
The primary benefit of Bt corn is to reduce yield losses. So growers who plant non-Bt corn hybrids and avoid paying the tech fee experience the most yield savings when areawide corn borer populations are reduced.
While previous cost-benefit pesticide studies focused directly on transgenic crop acres, this is the first research project to include the value of pest suppression in all fields.
“We knew there was going to be a benefit, but we didn’t know it was going to be that high,” says University of Minnesota entomologist William Hutchinson. He believes some growers would benefit even if they only planted 50% of their corn acres to Bt hybrids.
The Bt hybrids offer a built-in defense against attacks by the larvae of European corn borers and other insects. Larvae that ingest the Bt protein soon stop feeding and typically die within 48 hours. Because this trait is so effective at controlling corn borers and other pests, it’s used on over 60% of today’s U.S. corn acreage.
Other Crops Benefit
While not part of the study, the researchers maintain potato, green bean, and other host crops also stand to benefit from an areawide reduction of corn borers. The team also emphasized the need for proper use of non-Bt refuge areas and other strategies to reduce the corn borer’s ability to develop resistance to Bt and long-term effectiveness.
“The data shows resistant management is even more important than we thought,” says Paul Mitchell, an ag economist at the University of Wisconsin.
With the cost of corn hybrids containing numerous weed and insect traits continuing to skyrocket, make sure that you need all of the traits that you decide to buy. I’d be the first to admit that it’s not easy to make these calculations, but it’s going to be extremely important to decide what you need and what you want to pay for with so many different trait packages coming your way this spring.