The cotton bollworm caterpillar has evolved resistance to four Bt proteins produced by biotech crops. (Alex Yelich/University of Arizona)

Study: GM Crops, Touted For Pest Resistance, Rapidly Breed Resistant Pests

Genetically modified crops are controversial because of everything from environmental to human-health effects. Now a new study further calls into question their capacity to resist pests. Over time, the study confirms, it is pests that develop resistance and get the upper hand.