Scientists Call for Increase in Refuge Percentage

Bt crops have been proven to be effective in controlling pests as long as the pests do not evolve resistance to the toxin produced by the crop. The U.S. Environmental Protection Agency (EPA) required the use of refuge, or host plants that do not produce Bt toxin, to delay the pests' evolution of resistance. The EPA requires minimum refuges of 20% for Cry3Bb1 corn and 5% for corn producing two Bt toxins active against corn rootworms.

Scientists Bruce Tabashnik and Fred Gould from North Carolina State University suggested through an article that the refuge requirement be increased because Bt corn hybrids active against corn rootworms do not meet the high-dose standard, and western corn rootworm has rapidly evolved resistance to Cry3Bb1 corn in the laboratory, greenhouse, and field. Thus, they recommend that the minimum refuge for Bt corn targeting rootworms should be increased to 50% for plants producing one Bt toxin and 20% for plants producing two Bt toxins. They said that this increase in refuge percentage would help delay resistance, promote integrated pest management and sustainable crop protection.

Read the abstract at http://www.bioone.org/doi/abs/10.1603/EC12080.