EDIT
Monsanto, for its part, is reacting to the news with a hearty "move along—nothing to see here!" "Our
is effective," Monsanto scientist Dusty Post insisted in an interview with The St. Louis Post-Dispatch. "We don't have any demonstrated field resistance," he added, pretending away the Iowa study, to speak nothing those corn fields that are "toppling over" in Illinois and and Minnesota.
But the company's denials ring hollow for another reason, too. Bill Freese, science policy analyst for the Center for Food Safety, alerted me to this 2008 study, conducted by University of Missouri researchers and published by the Proceedings of the National Academy of Sciences on this precise question of Bt corn and rootworms.
The first thing to notice about the study is that Monsanto is listed in the acknowledgements as one of the "supporters." So this is Monsanto-funded research, meaning that he company would be hard-pressed to deny knowledge of it. The researchers found that within three generations, rootworms munching Monsanto's Bt corn survived at the same rate as rootworms munching pesticide-free corn—meaning that complete resistance had been achieved. Takeaway message: rootworms are capable of evolving resistance to Monsanto's corn in "rapid" fashion.
But such concerns were nothing new by 2008. From the early days of Bt-based GMOs in the '90s, everyone—Monsanto, the EPA, independent scientists—agreed that farmers would have to plant a portion of their fields in non-Bt corn to control resistance. The idea was that, as bugs in the Bt portion of the field began to develop resistance, they would mate with non-resistant bugs from the so-called "refuge" patch, and the resistant trait would be kept recessive within the larger bug population and thus under control.
EDIT
http://motherjones.com/tom-philpott/2011/09/monsanto-denies-superinsect-science