Click to view For years, farmers have been growing genetically-engineered cotton plants that exude an insecticide known as Bt. But now, a pest called the bollworm moth has evolved a resistance to Bt — and the altered bugs have already spread across part of the southern United States. This is the first-known example of bugs evolving resistance to an insecticide in the wild. It proves that natural selection can outrun genetic engineering in terms of its ability to transform a species quickly.
University of Arizona researcher Bruce Tabashnik said:
What we're seeing is evolution in action. This is the first documented case of field-evolved resistance to a Bt crop.
According to a University of Arizona release:
The researchers write in their report that Bt cotton and Bt corn have been grown on more than 162 million hectares (400 million acres) worldwide since 1996, "generating one of the largest selections for insect resistance ever known."
Tabashnik and his colleagues hasten to add that most bollworms have not become resistant, and that resistance has been known to happen in pest populations exposed to Bt spray. But this is the first time any creature has evolved a resistance to genetically-engineered crops containing Bt.
Another example of natural selection working this fast can be seen among elephants, who were hunted for their ivory tusks in the ninteenth and twentieth centuries. Over the course of a century, a "tuskless" mutation in a few elephants spread across the population like wildfire. While only 1% of elephants were born without tusks in 1930, in 1998 15% of female and 9% of male elephants were. Image via USDA-Agricultural Research Service.