U.S. scientists say Chinese farmers, among the world's first to plant genetically modified cotton, are being besieged by secondary pests.
The crop is known as Bt cotton -- shorthand for the Bacillus thuringiensis gene inserted into the seeds to produce toxins that prevent the most common cotton pest -- leaf-eating bollworms.
But now, after seven years, populations of other insects have increased so much, farmers must spray their crops as many as 20 times a growing season to control them, a Cornell University study of 481 Chinese farmers in five major cotton-producing provinces found.
"These results should send a very strong signal to researchers and governments that they need to come up with remedial actions for the Bt-cotton farmers," said Cornell Professor of Food, Nutrition and Public Policy Per Pinstrup-Andersen. "Otherwise, these farmers will stop using Bt cotton, and that would be very unfortunate."
Bt cotton can help reduce poverty and undernourishment in developing countries if properly used, Pinstrup-Andersen said.
The Cornell study -- the first to look at the long-term economic impact of Bt cotton - was reported Tuesday in Long Beach, Calif., during the annual meeting of the American Agricultural Economics Association.
Copyright 2006 by United Press International
Explore further: Thomas Edison's 'lost' idea: A device to hear the dead