"GM crops good for environment, study finds" | The Guardian
Plants engineered to repel pests use less pesticides, allowing natural insect predators to thrive and spread to non-GM fields
guardian.co.uk, Wednesday 13 June 2012 18.00 BST
Crops genetically modified to poison pests can deliver significant environmental benefits, according to a study spanning two decades and 1.5m square kilometres. The benefits extended to non-GM crops in neighbouring fields, researchers found.
Plants engineered to produce a bacterial toxin lethal to some insects but harmless to people were grown across more than 66m hectares around the world in 2011.
Bt cotton is one type and now makes up 95% of China's vast plantations. Since its introduction in 1997, pesticide use has halved and the study showed this led to a doubling of natural insect predators such as ladybirds, lacewings and spiders. These killed pests not targeted by the Bt cotton, in cotton fields, but also in conventional corn, soybean and peanut fields.
"Insecticide use usually kills the natural enemies of pests and weakens the biocontrol services that they provide," said Professor Kongming Wu at the Chinese Academy of Agricultural Sciences in Beijing, who led the research team. "Transgenic crops reduce insecticide use and promote the population increase of natural enemies. Therefore, we think that this is a general principle."...
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Peer-reviewed paper lede:
Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services
Over the past 16 years, vast plantings of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have helped to control several major insect pests 1, 2, 3, 4, 5 and reduce the need for insecticide sprays 1, 5, 6. Because broad-spectrum insecticides kill arthropod natural enemies that provide biological control of pests, the decrease in use of insecticide sprays associated with Bt crops could enhance biocontrol services 7, 8, 9, 10, 11, 12. However, this hypothesis has not been tested in terms of long-term landscape-level impacts 10. On the basis of data from 1990 to 2010 at 36 sites in six provinces of northern China, we show here a marked increase in abundance of three types of generalist arthropod predators (ladybirds, lacewings and spiders) and a decreased abundance of aphid pests associated with widespread adoption of Bt cotton and reduced insecticide sprays in this crop. We also found evidence that the predators might provide additional biocontrol services spilling over from Bt cotton fields onto neighbouring crops (maize, peanut and soybean). Our work extends results from general studies evaluating ecological effects of Bt crops1, 2, 3, 4, 6, 12, 13 by demonstrating that such crops can promote biocontrol services in agricultural landscapes.
Nature (2012) doi:10.1038/nature11153 Received 03 January 2012 Accepted 23 April 2012 Published online 13 June 2012
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