Researchers find use of GM cotton creates pest problems

China grows mainly GM cotton. The cotton was genetically modified to be resistant to a pest called known as the bollworm, a bug that loves to munch cotton.

Beijing, China - Considered to be sensitive to pests, cotton was long ago genetically engineered to keep the crop profitable for farmers. China has readily embraced GM cotton, which had provided benefits for farmers. However, a study published in Science this week said GM cotton, which contains Bt, is associated with the increase of insect predation of cotton and other crops. In Mirid Bug Outbreaks in Multiple Crops Correlated with Wide-Scale Adoption of Bt Cotton in China (accessible through SciDevnet here), the researchers conclude

"In many parts of the world, transgenic crops such as Bt crops have come to dominate agricultural landscapes, and their landscape-level impact has been quantified on target pests, non-target organisms such as natural enemies or charismatic species such as the monarch butterfly Danaus plexippus. However, few studies have described the impact of transgenic crops on non-target insect pests or, more specifically, assessed their landscape level effects. To our knowledge, this study is the first confirmed report of a landscape-level emergence of nontarget pests with the adoption of Bt crops due to reductions in insecticide applications. Our work highlights a critical need to predict landscape-level impacts of transgenic crops on (potentially) pestiferous organisms in future ecological agricultural risk assessment. Such more comprehensive risk management may be crucial to help advance integrated pest management and ensure sustainability of transgenic technologies."

Of concern to the team of eight Chinese researchers was the increase in the numbers of an insect called the Mirid bug. Before Bt cotton, the scientists said, the Mirid bug was a nuisance, but not an agricultural pest. Now the Mirid bug is so populous in parts of China where Bt cotton is grown, the insect has attained pest status. The transgenic cotton works through having genes from a bacteria, Bacillus thuringiensis (Bt) inserted into cotton genes. Insects that would normally munch on the cotton are killed by the bacteria. But that is not the problem -- the Bt cotton is doing the job it was intended to do. Rather, the issue with Bt cotton, summed up the research team, is the reduced need to apply pesticides has allowed Mirid bugs, which are not affected by Bt, to take advantage of the ecological niche created by the transgendered cotton crop. The Bt cotton has been a boon for Chinese farmers, who not only benefited from less exposure to toxins, but who also have benefited financially -- before the Mirid bug became such a force to contend with. In 2006, researchers at Cornell highlighted the threats posed by the increase in Mirid bugs, saying

"The problem in China is not due to the bollworm developing resistance to Bt cotton -- as some researchers have feared -- but is due to secondary pests that are not targeted by the Bt cotton and which previously have been controlled by the broad-spectrum pesticides used to control bollworms."

Not only is the Mirid bug now a pest in the cotton fields, the researchers found, the insect also threatens fruit and agricultural production.

"... our analyses show that Bt cotton has become a source of mirid bugs and that their population increases are related to drops in insecticide use in this crop."

The research report released this week warns

"... Long-term ecological effects of transgenic Bacillus thuringiensis (Bt) crops on non-target pests have received limited attention, more so in diverse smallholder-based cropping systems of the developing world."

Monsanto has a very large interest in Chinese GM cotton production, reveals a study titled 'Bt Cotton Benefits, Costs, and Impacts in China.' Monsanto, in collaboration with the Chinese National Cotton Research Institute developed several species of transgenic cotton in the mid-90s for China. GM cotton has been widely adopted in China. Monsanto's GM cotton is now a major crop in other developing countries, such as Pakistan, although India is sitting on the fence when it comes to GE agricultural crops. There are other problems inherent in growing Bt cotton. It is possible that bollworm resistance is starting to develop, as Monsanto found resistance of the bollworm to Bt cotton in parts of India in 2009. The company has said this was an isolated occurrence, and would not likely be repeated. In a brochure that discusses the importance of genetically modified crops for farmers around the world, Monsanto said

"After 13 years of use on more than 2 billion acres (800 million hectares) worldwide, plant biotechnology delivers proven economic and environmental benefits, a solid record of safe use and promising products for our future."

Studies at the University of Guelph have confirmed that a species of ragweed is now resistant to Monsanto's herbicide, Round-up. The plant has genetically adapted to Round-up, able to survive applications of the herbicide and also capable of passing on the resistance to a new generation of plants. Monsanto has not yet responded to the Chinese research findings.