Overly optimistic assumptions about transgenic crops that produce two or more Bt toxins active against the same pest can lead to inadequate strategies for delaying evolution of pest resistance, says University of Arizona.

New insights into the mechanisms of action of Cry1Ab and Cry1Ac served as the basis for development of modified Bt toxins.

Bags of corn seed that mix genetically modified hybrids with and without Bt toxins that kill insects provide farmers easier compliance with federal regulations but could, over time, hasten insect resistance to Bt, a Purdue University entomologist said.