Genetically modified crops encourage beneficial bugs

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.

Protesters in the UK recently threatened to disrupt a trial at Rothamsted Research in Harpenden of a GM wheat that gives off a scent repelling aphids. Rothamsted's John Pickett said the Chinese research is exciting because it shows that certain GM crops can spread beneficial insects to neighbouring farms.

Dispelling myths

"This is another chapter of research dispelling the myth that GM crops are environmentally damaging," says Julian Little, chairman of the UK's Agricultural Biotechnology Council, which backs GM crops.

In 2010, Paul Mitchell of the University of Wisconsin-Madison found that US growers of conventional maize benefitted economically from having an adjacent Bt maize farm, because it suppressed maize-damaging pests. "This paper is part of the ongoing research documenting the environmental, economic and social benefits that Bt crops generate for more than just their users," he says.

But the Soil Association, which represents organic farmers in the UK, says earlier data from the same Bt cotton study shows that new insect pests may emerge, forcing farmers to increase crop spraying (Science, DOI: 10.1126/science.1187881).

Journal reference: Nature, DOI: 10.1038/nature11153

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