"Corn rootworms can cost U.S. farmers close to $1 billion each year. Bt corn has helped to reduce these costs and to decrease insecticide sprays, but evolution of resistance by the pests can diminish or even eliminate these benefits," said Tabashnik, who heads the department of entomology in the UA College of Agriculture and Life Sciences.
"To delay pest resistance and sustain the benefits of Bt corn, we recommend planting more corn that does not produce Bt toxins active against rootworms. This refuge strategy allows the susceptible pests to survive and has worked to slow resistance of other pests to Bt crops."
"Most of the corn seed currently produced in the U.S. is transgenic and includes genes for insect control," said Gould. "Enlarging refuges will require more seed without corn rootworm control genes. This shift in production will take time, so this process should begin immediately."
In addition to increased refuge sizes, the authors write that the best way to postpone resistance is to use IPM, in which Bt corn is combined with other control tactics such as crop rotation and judicious use of insecticide sprays.
"We advocate greater use of integrated pest management, which is a common sense approach based on the best available combination of tactics," Tabashnik said. "The goals are to limit pest damage, maximize farmer profits and preserve environmental quality. Maintaining the effectiveness of Bt toxins can help us achieve these goals."
"We're seeing the early signs of rootworm resistance to Bt corn, which fit predictions from evolutionary theory and experiments in the lab and greenhouse," he added.
The paper indicates rootworm resistance to Bt corn was first detected in 2009 in Iowa; six years after sales of rootworm-killing Bt corn began
|Contact: Daniel Stolte|
University of Arizona