Farmers use as much pesticide with GM crops

Researchers at Cornell University released a report on July 25 that undermines claims of the biotechnology industry that genetically modified (GM) technology can boost food production without necessarily damaging the environment with pesticides. The study involved detailed interviews of 481 Chinese cotton growers who had switched to cotton that had been genetically modified with a gene for a bacterial toxin, Bt, which is highly effective at stopping the growth of bollworm, a major pest of the crop. Bt cotton, introduced in 1996 by the Monsanto Corporation, accounts for 35 percent global cotton cultivation today, and is used by over five million cotton farmers in China. The study found that, before the introduction of the GM crop into China, farmers in the country had to spray an average of 20 times each growing season to control bollworm. By 1999, three years after the introduction of Bt cotton, the average number of pesticide treatments per growing season fell to below seven, GM farmers pesticide use was cut by 70 percent, and earnings of GM farmers averaged a third more than that of conventional farmers. However, the benefits of the GM crop were short-lived and have since been largely lost due to the rise of other pests that were not considered a problem for cotton. "Using a household survey from 2004, seven years after the initial commercialization of Bt cotton in China, we show that total pesticide expenditure for Bt cotton farmers in China is nearly equal to that of their conventional counterparts," the scientists say in their report. "Detailed information on pesticide expenditures reveals that, though Bt farmers saved 46 percent of bollworm pesticide relative to non-Bt farmers, they spend 40 percent more on pesticides designed to kill an emerging secondary pest," they say. Secondary pests, such as a type of leaf bug called mirids, are not normally a problem in cotton fields because bollworm, and sprays against bollworm, tend to keep them in check. However, because Bt cotton is targeted mainly against bollworm, other pests are able to exploit the relatively low use of pesticide that such fields need. The average net income of the Bt cotton farmers in 2004 was eight percent less than conventional farmers of that same year due to the high cost of Bt cotton seed, which is three times that of conventional seed.