"Some of the most popular products of biotechnology — corn and cotton plants that have been genetically modified to fend off insects — are no longer offering the same protection from those bugs. Scientists say that the problem results from farmers overusing the crops, and are pushing for new regulations.
These crops were the original genetically modified organisms, or GMOs. They weren't the first ones invented, but they were the first to be widely embraced by farmers, starting in the late 1990s.
They got their bug-resistant features from a kind of bacteria that lives in the soil, called Bacillus thuringiensis, or Bt, which is poisonous to the larval stage of some major insect pests, including the corn rootworm and cotton bollworm. Scientists inserted some of these bacterial genes into corn and cotton, and the plants themselves produced these insect-killing proteins."