Corn rootworms are one of the most devastating insect pests of corn in the United States. They inflict damage as larvae feeding on the roots of young corn plants in farmers’ fields. This damage inhibits the plant's ability to take up water and nutrients, decreases its ability to develop and remain upright, and ultimately leads to yield loss.
As you mentioned, Monsanto and other companies have developed insect-protected plants using B.t. (Bacillus thuringiensis) in order to protect corn plants from corn rootworm damage and significantly decrease the need for a farmer to apply chemical pesticides. Today, many U.S. corn farmers plant B.t. corn hybrids to manage corn rootworm populations in their fields.
The challenge is that – while B.t. hybrids sustain less damage from corn rootworm than non- B.t. corn – B.t. hybrids still can be overwhelmed by heavy insect infestations in a field. In some areas in the U.S., there are pockets of heavy rootworm infestations – especially in fields where farmers have a long history of planting corn every year.
And, each year since the launch of B.t. corn, we have had some farmer customers who report a field that is overwhelmed by the corn rootworm. Anytime that occurs, we work one-on-one with the farmer to understand what has happened and to provide best management recommendations that fit the farmer’s need and help reduce rootworm populations and limit rootworm damage in the future. Overall, fields that are affected represent less than 0.2% of all the acres planted with these B.t. hybrids across the U.S.
So while corn rootworm resistance is suspected in a number of isolated fields across the Corn Belt, the vast majority of farmers who grow these hybrids continue to have great success with our products – including those few farmers who see unexpected damage but are able to successfully control the corn rootworm populations on those fields with best management practices the next year.
As one of the entomologists at Monsanto focused on monitoring and controlling corn rootworm populations, I can confirm that we are committed to the success of our farmer customers and to ensuring these traits remain a viable and sustainable way to control the corn rootworm pest for years to come. If you are interested in learning more, I’d recommend you visit our web site http://www.monsanto.com/products/Pages/corn-rootworm.aspx where you will find additional information.