The reason, as reported by Cornell University researchers at the American Agricultural Economics Association (AAEA) Annual Meeting in Long Beach, Calif., today (July 25), is that other pests are now attacking the GM cotton.
The GM crop is known as Bt cotton, shorthand for the Bacillus thuringiensis gene inserted into the seeds to produce toxins. But these toxins are lethal only to leaf-eating bollworms. After seven years, populations of other insects - such as mirids - have increased so much that farmers are now having to spray their crops up to 20 times a growing season to control them, according to the study of 481 Chinese farmers in five major cotton-producing provinces.
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. Otherwise, these farmers will stop using Bt cotton, and that would be very unfortunate, said Per Pinstrup-Andersen, the H.E. Babcock Professor of Food, Nutrition and Public Policy at Cornell, and the 2001 Food Prize laureate. Bt cotton, he said, can help reduce poverty and undernourishment problems in developing countries if properly used.
The study - the first to look at the longer term economic impact of Bt cotton - found that by year three, farmers in the survey who had planted Bt cotton cut pesticide use by more than 70 percent and had earnings 36 percent higher than farmers planting conventional cotton. By 2004, however, they had to spray just as much as conventional farmers, which resulted in a net average income of 8 percent less than conventional cotton farmers because Bt seed is triple the cost of conventional seed.
In addition to Pinstrup-Andersen, the study was
Source:Cornell University News Service