GM crops `only kill harmful insects'

ONE OF the most detailed studies of genetically modified (GM) crops has found that they are potentially more beneficial to wildlife than conventional spraying with pesticides.

Scientists found that GM crops designed to kill insect pests had no effect on beneficial insects, which contradicts work published earlier this year showing that GM pollen can harm the endangered monarch butterfly.

The publicly-funded scientists from the Institute of Arable Crops Research (IACR) in Harpenden, Hertfordshire, showed that although GM oilseed rape can kill pests such as the larvae of the diamondback moth, it was harmless against useful insects, notably the parasitic wasp that attacks the moth larvae.

"One of the biggest worries of transgenic [GM] plants is not only how they affect pretty things like the monarch butterfly but how they affect the complex interactions in the environment," said Dr Guy Poppy, who led the research team at the IACR.

The researchers believe that GM crops might work more harmoniously with beneficial insects compared with insecticides which kill everything.

More realistic experiments that enable crop pests and beneficial insects to behave more naturally show that GM crops are less likely than chemical sprays to damage beneficial wildlife, they say.

The team investigated the effects of allowing the diamondback moth larvae to feed off oilseed rape that was genetically modified with a toxin derived from a bacterium called Bacillus thuringiensis (Bt).

Results of the experiment, published in the journal Nature, show that parasitic wasps which feed off the moth larvae died along with the larvae when they were forced to eat the GM oilseed rape. However, the scientists showed that this was not a direct result of the wasps eating the toxin of the GM plant, but merely a consequence of having their food source destroyed.

Wasps that parasitised a strain of diamond-back moth that is resistant to Bt toxin were not harmed, even though the larvae were heavily contaminated with the Bt toxin.

In another experiment, the scientists showed that GM crops did not affect the parasitic wasps ability to locate and feed off the moth larvae.

Dr Poppy said the results indicate that pesticide resistance will be less of a problem with GM crops because they still enable beneficial insects, such as the parasitic wasp, to survive.

"With insecticide spraying you would have a worse problem because you would kill beneficial insects and not kill some of the pests that develop resistance." he said.

GM protesters have argued that British "farm-scale" trials, in which sites of several acres are being planted with GM oilseed rape and maize to assess the environmental impact, could endanger such species directly - meaning that simply by running the trials, the environment would be irreversibly affected. Some of the protesters have been arrested for damaging several of the trial crops.