Monsanto Co., the world's biggest seed company, said 100,000 acres of corn in Iowa and Nebraska may harbor rootworms that developed resistance to the company's insect-killing biotechnology.
The area represents less than 1 percent of the acres planted with the biotech corn, Graham Head, global lead for insect-resistance management at St. Louis-based Monsanto, said Monday. The crop is engineered to produce insect-killing protein derived from Bacillus thuringiensis, or Bt, a natural insecticide.
"Ninety-nine percent plus of our customers are still getting a really good experience with that technology," Head said. "The impacted acreage is maybe somewhere around 100,000 acres."
That estimate is based on Monsanto's investigations of "unexpected damage" to crops and work with Aaron Gassman, an entomologist at Iowa State University in Ames, who reported in July finding four fields with Bt-resistant insects, Head said. Monsanto's monitoring hasn't uncovered resistance, only areas of unusually high rootworm populations and crop damage, he said.
Monsanto's technology is the first to develop bug resistance because it has been on the market for years longer than Bt corn developed by rivals such as DuPont Co., Gassman said. Other technologies may also fail to perform with time, he said.
"The general pattern in terms of pest survival and anticipated pest genetics is similar among all Bt traits, so I think we need to be concerned for all products on the market," Gassman said in the telephone interview. "It's basically an early warning."
The Environmental Protection Agency requires modified corn that incorporates pesticide to be grown among some conventional plants to thwart the emergence of pesticide-resistant insects. To prevent resistance, Monsanto recommends farmers rotate crops, plant the required refuge of non-Bt corn and use SmartStax seeds introduced in 2010 to kill rootworms with a second mode of action, Head said. Gassman said that is good advice.
"While we understand why this news might appear alarming to investors worried that Monsanto's products are losing their efficacy, we would highlight that this seems to have occurred in very few instances," Robert Koort, a Houston-based analyst at Goldman Sachs Group Inc., said Monday in a report.
When the pink bollworm developed resistance to a Bt cotton trait in India a couple of years ago, Monsanto added a second Bt gene to cotton and urged growers to be vigilant about planting a non-Bt refuge, Head said. Monsanto plans to add third and fourth modes of insect control to its U.S. corn seeds later in the decade, he said.
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