Bt Cotton Protects Nearby Crops from Pests

Genetically engineered cotton expressing Bt proteins not only reduces pest populations among those crops, but also reduces pests among other nearby crops that have not been modified with Bt, scientists from the Chinese Academy of Agricultural Sciences found out. Their work appears in the current issue of Science.

Kung Ming Wu and colleagues analyzed data from 1997 to 2007 about the agriculture of Bt cotton in six provinces in northern China, covering 38 million hectares of farmland cultivated by 10 million farmers. They compared the data with information on pest populations in the region, focusing on the cotton bollworm (Helicoverpa armigera). The team found out that introduction of Bt cotton, especially during the period of 2002-2006, led to reduced bollworm population not only on cotton but also on other host crops. Wu and the team of researchers suggest that this may be because Bt cotton is usually the main host of the first generation moths to lay eggs and acts as the source of the subsequent generations for other host crops.

Wu and colleagues acknowledge that insects have the potential to evolve resistance to the Bt toxin and Bt cotton should not be relied upon as a single method of pest control.

The paper is available at http://dx.doi.org/10.1126/science.1160550 For more information, read http://www.aaas.org/news/releases/2008/0918china_cotton.shtml