A Long Lens
WHEN IT COMES TO basic biology, even GM crop proponents worry that gains made by modified plants are only temporary. After all, evolution does not stop for technology. Insects, for instance, may evolve strategies for overcoming Bt technology and eventually consume the transgenic plants with no effect.
Or nature may take a different tack, as suggested by the first long-term economic impact study of Bt cotton in China. That study, presented by Cornell University researchers at the July 2006 meeting of the American Agricultural Economics Association, found that farmers planting Bt cotton--designed to defy the leaf-eating bollworm--initially prospered, cutting pesticide use by 70 percent. By year seven of Bt cotton farming, however, secondary insects such as mirids crept in, replacing the bollworm as the star scourge--and forcing farmers to return to typical spraying levels, even as they paid for Bt seed, which costs two to three times more than conventional seed.
That does not surprise Alison G. Power, an ecology professor at Cornell. "When we breed traditional plants that are resistant to some particular pest, the next most important pest moves in," Power explains. "We see this all the time with plant viruses."
Rebecca Goldburg, a senior scientist at Environmental Defense, predicts that farmers will eventually lose Bt as an effective control against insects and will then move on to another chemical control. "Many of us view this current generation of biotech crops as a kind of diversion, rather than a substantive gain, for agriculture," Goldburg says.
Like scientists, politicians are at odds over GM crops. During the 2005 legislative session, 117 pieces of legislation related to agricultural biotechnology were introduced in 33 states and in the District of Columbia. Many state legislatures attempted to disallow local and county efforts to ban or limit GM seeds and crops. Of the 23 state bills that passed during 2005, two thirds supported GM technology, according to the Pew Initiative on Food and Biotechnology.
More than anything, the public is just plain confused about GM crops, as reported in a survey released in 2005 by the Food Policy Institute at Rutgers University. In the survey of 1,200 U.S. residents, about half said they were unsure or could not take a position on GM foods. Roughly a fourth of them approved of GM technology, but almost as many disapproved. Lead author William Hallman, a Rutgers psychologist, concluded that people "seem to be willing to believe just about anything they hear about GM foods." The study suggests that fewer than half of Americans realize that supermarkets regularly sell GM foods.
Like them or not, GM crops are poised to grow--and not just in the U.S. In 2005, according to the ISAAA, 38 percent of the land planted in GM crops was in developing countries, which desperately need plant varieties that tolerate drought and improve yield, among other traits. In 2006 Iran produced its first full-scale commercial seed supply of Bt rice. China is expected to follow. "Yes, this technology will have to be modified, due to resistance factors, the appearance of new pests and other challenges," Vaituzis says. "But genetically modified crops are here to stay."
KATHRYN BROWN is a science writer based in Alexandria, Va. She frequently writes about botany, ecology and earth science for magazines such as Scientific American and Science. Brown is a member of the board of the D.C. Science Writers Association.