鈥淏E IMPRESSED. Be very impressed.鈥� This was the message last week from Joe Perry, a pugnacious member of the scientific steering committee that oversaw the British government鈥檚 farm-scale trial of genetically modified crops. And no one could disagree that the trial was impressive: over four years, researchers made 4000 visits to some 283 trial fields and collected and analysed 1,000,000 plants, 750,000 seeds and 1.5 million invertebrates caught in traps and sucker machines.
The trial was the largest scientific investigation of farm ecology the world has seen. It was launched in 1999 to address fears expressed by English Nature, one of the government鈥檚 wildlife advisers, that the powerful weedkillers applied to GM crops might hasten the decline in farmland wildlife that began with the birth of modern farming 50 years ago. They investigated whether three flagship weedkiller-resistant GM crops 鈥� oilseed rape, sugar beet and maize 鈥� were better or worse for wildlife than their conventionally bred counterparts.
To the delight of anti-GM activists, two out of the three 鈥� the rape and the beet 鈥� flopped miserably, vindicating English Nature鈥檚 concerns (Philosophical Transactions of the Royal Society B, vol 358, p 1775). Many commentators declared the results the final nail in the coffin for GM crops, and called for the government to ban them all for good. Even the news that GM maize is better for wildlife is 鈥渢ainted鈥�, critics say, because the conventional maize was treated with atrazine, a powerful herbicide that will soon be banned in Europe.
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But in the long run the trial could tell us much more about how to rescue the UK鈥檚 wildlife than the debate about whether the country should 鈥済o GM鈥�. For a start, it shows that the crucial factors for wildlife are the type of herbicide farmers apply and when they apply it, rather than whether the crop is GM or not. The results were remarkably consistent, no matter where in the UK the crops were grown, or which year, says Les Firbank, who coordinated the trial from the Centre for Ecology and Hydrology in Merlewood, Cumbria. They would have been the same, he says, if the crops had been made resistant to the herbicides through conventional breeding, a strategy that GM companies might now pursue instead (快猫短视频, 18 October, p 8).
But the big untold story, says Firbank, who is interviewed on page 46 of this issue, is the massive differences between the impacts that the three different crops 鈥� conventional or GM 鈥� had on wildlife. In many cases, these differences dwarfed those between a GM crop and its conventional variety. For instance, researchers collected an average of 1707 beetles over a year in conventional beet fields, marginally ahead of the 1576 found in GM beet fields. Yet this is more than double the number of beetles found in GM or conventional maize, and 50 to 60 per cent more than the number found in rape. Maize, whose GM variety was better for wildlife than its conventional counterpart, turned out to be worst for wildlife overall on many counts.
Astonishingly, these differences between maize, rape and beet had never before been systematically investigated, and they emerged from the latest trials more by accident than design. What鈥檚 more, the three crops collectively cover just 10 per cent or so of the UK鈥檚 arable land, compared with the 50 per cent covered by wheat, which ecologists strongly suspect to be the most wildlife-barren crop of all. Does this mean we should forget about the minor differences between GM and non-GM crops and simply grow less wheat?
Brian Johnson, the GM adviser to English Nature who first called for the trials, wants the government to encourage farmers to return to mixed farming, raising animals as well as crops. A more varied landscape would attract more visitors, and Johnson suggests that tourism has the potential to bring more money to the countryside than growing food. Encouraging farmers to grow crops with an eye to conservation would tie in with recent attempts to link European Union farm subsidies to environmentally friendly practices.
Rape, beet and maize are crucial to wildlife in the British countryside, despite the small amount of land they cover, because farmers plant them in rotation with cereals as 鈥渂reak crops鈥�. That is why the GM results from the trial are important, says Johnson. But potentially the trial鈥檚 most valuable legacy will be the vast database of ecological information it has generated, which might help us plan the sort of countryside landscape we want and achieve a balance between food production and nature.
Last week, when the results were unveiled in London, even an anti-GM activist who was sitting next to me expressed his admiration, not least since for seven weeks he had been removing all the insect traps from one of the trial maize fields. The fact that he sat through the presentations without disrupting them and joined in the applause at the end gives hope that the debate might now move forward.