A study in northern China indicates that genetically modified cotton, altered to express the insecticide, Bt, not only reduces pest populations among those crops, but also reduces pests among other nearby crops that have not been modified with Bt. These findings, reported in the latest issue of Science, could offer promising new ideas for controlling pests and maximizing crop yields in the future. Bt is an insecticide derived from the spores and toxic crystals of the bacteria Bacillus thuringiensis, and has been sold commercially since 1960. It is considered non-toxic to humans, animals, fish, plants, micro-organisms, and most insects. However, it is highly selective and lethal to caterpillars of moths and butterflies. It does not contaminate groundwater because it degrades so rapidly.
The authors say that Bt technology gives China a new tool for pest control, and that all farmers in a Bt cotton-planting region will experience the benefits. "In 1992, cotton bollworms caused about a 30% loss in the cotton yield in northern China. Because of the high costs for pest control then, many farmers refused to plant cotton," said Wu in an email interview. "This case study of Bt cotton implies that other Bt crops, such as Bt rice, may also have great potential for agricultural practices in China. This success with Bt cotton could push forward the commercial processes of genetically modified crops in China."
The use of Bt cotton and other genetically modified crops could provide a safer and more economical solution to pest control in many small farms around the world. Wu and the team of researchers, however, acknowledge that a major challenge to the success of Bt cotton is the potential for insects to evolve resistance to the insecticide. They insist that despite its considerable value, Bt cotton should still be considered only one component in the overall management of pests.
source : http://www.aaas.org/news/
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