Laboratory bioassays conducted by Texas A&M AgriLife researchers have confirmed the presence of Southwestern corn borers (SWCB) resistant to the Bt toxins Cry1F, Cry1A.105, and Cry2Ab2 in Southern New Mexico and Southeastern Arizona, US. Texas A&M AgriLife Extension is assessing the scope of resistance in New Mexico and Arizona and surveying for resistant populations in other Southwestern states.