Rootworm transgenic products in first year corn: Appropriateness, feasibility of refuges, and the possibility of community refuges
Michael E. Gray, email@example.com and Kevin L. Steffey, firstname.lastname@example.org. University of Illinois, Crop Sciences, 1102 South Goodwin Avenue, Turner Hall, Urbana, IL
The variant western corn rootworm, Diabrotica virgifera virgifera LeConte, continues to expand its range across the eastern Corn Belt of the U.S.A. Rotated cornfields (first-year cornfields) are susceptible routinely to larval injury in east central and northeastern Illinois. Corn rotated with soybeans in northern Indiana, southern Michigan, and western Ohio also is potentially susceptible to economic losses caused by the variant western corn rootworm. Soil insecticide use has increased due to the failure of crop rotation as a pest management tactic. Some new and popular (John Deere) planters do not come equipped with insecticide boxes. This planter design will present some challenges with respect to the establishment of refuges when transgenic seed for corn rootworms is used. This challenge becomes particularly acute when refuges are deployed in narrow strips. Modeling efforts have suggested that the two most effective approaches to prevent or slow the spread of the variant western corn rootworm is to plant transgenic corn in a 2-year rotation pattern or utilize a 3-year rotation of corn, soybean, and wheat. In this second scenario, wheat is presumed to be less susceptible to oviposition by the variant western corn rootworm. The establishment of community refuges used in combination with coordinated scouting programs and economic thresholds (in soybeans) could jointly form the core of an IPM/IRM program that utilizes transgenic corn rootworm hybrids in rotated corn production systems.