Friday, June 15, 2012

A genetically modified crop produces spillover benefits

Here's a mind-bender for people who oppose genetic modification of crops. Bt cotton reduced farmer's needs for pesticides--on neighboring fields as well as on fields where the Bt cotton was grown.

That's right, if I grow Bt cotton and you, my neighbor, don't grow Bt cotton, you might get a spillover benefit of having more predatory insects in your fields, and you might need less pesticide on your cotton.

According to the New Scientist:

Environmentalists might one day run barefooted through insect-rich fields of genetically modified crops. At least, they might if the conclusions of a two-decade study in China hold up.

Kongming Wu of the Chinese Academy of Agricultural Sciences in Beijing and colleagues looked at the impact on surrounding farms of Bt cotton, a GM crop that protects itself against bollworm larvae by making its own pesticide.

As pesticide sprays were no longer needed, beneficial predator insects such as ladybirds, spiders and lacewings could thrive and spill over onto neighbouring farms, where they ate aphids. This reduced the amount of pesticides neighbouring farmers used.

"Transgenic Bt crops with less insecticide use can promote population increases of predators in the whole agricultural landscape," says Wu.

This study alone won't settle anything, and criticisms remain against Bt cotton. But this spillover effect deserves attention in the debate over the future of agriculture.

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