when genetically modified (gm) plants were introduced in 1996, some researchers said pests were too smart to be controlled and would eventually develop resistance. There is now evidence that the cotton pest, bollworm, has done this in less then a decade.

Researchers from the University of Arizona have found resistant bollworms in the cotton fields of Mississippi and Arkansas in the us. This is the first ever documented case of field-evolved resistance to Bt crop. "What we are seeing is evolution in action,' said Bruce Tabashnik of University of Arizona, who led the research team. They found bollworm survives despite high doses of Bt toxin, which was not the case, say, five years ago. The study indicated with time Bt will cease to be an effective form of insecticide. The researchers analysed data from Australia, China, Spain and the us collected during 2003