Insecticide inside: gene-modified rice cuts chemical spraying in China.

In the hands of a sample of rural Chinese farmers, varieties of rice genetically modified (GM) to be insect resistant reduce pesticide use and increase crop yields, according to a new study.

Some scientists greet the finding as a demonstration of biotechnology's promise to prevent environmental damage and pesticide-related illnesses. But others emphasize that the study addresses neither potential risks to consumers nor the possibility that insects might quickly adapt to the modified crop, forcing farmers once again to resort to heavy pesticide use.

In the new study, agricultural economist Carl Pray of Rutgers University in New Brunswick, N.J., and his colleagues examined two varieties of modified rice from among the several GM rice strains that the Chinese government has developed and is considering commercializing. One variety contains a gene from Bacillus thuringiensh', the same baeterium used to engineer socalled Bt corn, which makes its own pesticide. The other vice plant possesses a cowpea gene. Both inserted genes make toxins that control pests such as the rice-stem borer.

In the most advanced field test of genetically modified rice so far, the researchers compared the performances of the GM plants and of traditional rice on 109 family farms in eight Chinese villages in 2002 and 2003.

At the end of each year, Pray and his cop leagues asked each family how many times it had sprayed pesticides on its fields and whether anyone in the household had developed certain types of illness. The investigators also quantified how productive each plot of land had been.

Fields planted with traditional rice typically received 21 kilograms of pesticides per hectare annually, while those sown with either GM variety received much less or none at all. Overall, the use of GM seeds resulted in a nearly 80 percent drop in pesticide use, the researchers report in the April 29 Science. At the same time, the modified seeds produced at least 6 percent more rice per hectare than traditional seeds did.

Some members of families growing traditional rice, but none of those growing GM rice, reported coming down with illnesses that have been associated with pesticide spraying.

Environmentalists "should be delighted that pesticide use is down," says plant geneticist Nina Fedoroff of Pennsylvania State University in State College. "Pesticide poisoning is a serious problem in China."

Pray adds that China could become the first country to get a significant amount of its food from GM crops.

But Greenpeace science adviser Doreen Stabinsky of the College of the Atlantic in Bar Harbor, Maine, says the new study is "answering the wrong questions." Researchers need to study the health consequences of millions of people regularly eating GM food containing toxin-producing genes, she says. Scientists should also determine how quickly insects will evolve to cope with the toxins, she says.

"So far, all of the terrible predictions [for GM crops] have not been borne out," says Fedoroff. "Having said that, there's no doubt that some pesticide resistance will develop."