SIGNIFICANT western corn rootworm larval injury to corn has been confirmed in the Illinois counties of Livingston and Kankakee by Michael Gray and Joe Spencer, entomologists with the Illinois Natural History Survey at the University of Illinois.
The first-year corn fields were planted with VT Triple PRO RIB with the expressed Cry3Bb1 protein, a Monsanto trait.
Spencer collected numerous adult western corn rootworms in the damaged corn fields and adjacent soybean fields.
"The number of beetles in the soybean fields was reminiscent of densities in the late 1990s and early 2000s — very impressive," Gray noted. "The density of western corn rootworm adults in both crops, along with the severe pruning and lodging, was additional evidence that the Bt hybrids had failed to offer the necessary root protection."
Adult western corn rootworms were collected, and bioassays are being conducted to determine if these rotation-resistant western corn rootworms are also resistant to the Cry3Bb1 protein. The results have yet to be released.
According to the U.S. Department of Agriculture, damage caused by corn rootworm has cost farmers an estimated $800 million in lost yield and an additional $200 million in treatment expense annually.
In areas prone to high populations of corn rootworm, Gray recommended that growers implement a suite of best management practices. Planting seed that contains a trait package employing multiple modes of action, or pyramided Bt hybrids that express more than one rootworm Cry protein, is best. If planting single-trait Bt hybrids, such as VT Triple Pro, then growers should incorporate a soil-applied insecticide to the field, he said.
According to Gray and Spencer, reports have indicated similar rootworm damage in parts of Indiana, Michigan, Ohio and Iowa. They encouraged corn growers, especially in the northern two-thirds of Illinois, to take a closer look at their fields.
"From the roadside, it is very easy to overlook areas of fields that may be lodged. I suspect that during harvest, many producers may be surprised to see pockets within fields that have been severely damaged by corn rootworms," Gray said.
Michigan State University and Monsanto Co. are collaborating to support research on corn rootworm.
The Corn Rootworm (CRW) Knowledge Research Program, which started in early 2013, will be extended to 2016 with Monsanto's pledge of an additional $3 million for academic-supported research on corn rootworm.
The program provides merit-based awards of up to $250,000 per year for outstanding research projects that address a number of corn rootworm-related topics, including the economics of corn rootworm management, the development of predictive models, the characterization of resistance and the development of broad survey methods.
"The extension of this program will further increase the intense research efforts by our best public-sector researchers on this challenging and damaging pest," program co-chair Dr. Steve Pueppke, associate vice president for research and graduate studies at Michigan State University, said. "This research will ensure better management practices that will be effective and sustainable for the benefit of corn producers."
The CRW Knowledge Research Program is guided by a 10-person advisory committee that is co-chaired by Pueppke and Dr. Dusty Post, Monsanto's global insect management lead. Additional committee members include experts from academia and agricultural organizations who were selected based on their expertise in corn rootworm biology and insect management practices.
"By working collaboratively to increase our collective understanding of corn rootworm biology and pest management, we can combat this challenging pest while providing economical, practical and sustainable solutions for farmers," Post said.