GM crop trials: Why?

The GM issue is not about how many butterflies can fit on a beet leaf.

Tony Gilland

Topics Science & Tech

Finally the results of the UK government-sponsored ‘GM-Crop Farm-Scale Evaluation’ trials have been published. But are we any the wiser?

On 16 October, some 100 journalists and 10 camera crews turned up at the Science Media Centre in London to find out what the scientists had discovered. Hot on their heels were another 200-odd NGO representatives, farmers and interested parties who came to hear a similar briefing from the scientists in the afternoon at the Royal Institution.

Four years, £5.9million and (apparently) 1.5million dead invertebrates on from the start of the farm-scale trials, the scientists are clearly excited about the unique opportunity that they have had to study farmland ecology at such a detailed and extensive level and, quite reasonably, are proud of their work. But while the scientific experiment has yielded some interesting results, it has not helped one bit in answering the vexed question of whether the UK should get on and experiment with the commercial growth of genetically modified GM crops.

From the start, the farm-scale trials were an attempt by the UK government to evade making a decision about GM, in the face of controversy that has surrounded this technology since 1997. These large trials were a conciliatory gesture towards GM’s opponents, designed to show that it took seriously the myriad of environmental concerns raised about the impact of GM upon farmland biodiversity. The trials have now shown, though surely to nobody’s surprise, that GM will have an impact – but whether that impact should be seen as good, bad or indifferent primarily depends upon the attitude of the beholder towards GM.

Formally speaking, the purpose of the trials was to evaluate the indirect environmental impacts of growing genetically modified maize, beet and spring-sown oil seed rape. These crops have all been modified to make them resistant to certain broad-spectrum herbicides. The purpose of this is to make life easier and cheaper for farmers, by assisting them to control the weeds in their fields without fear of damaging the crops themselves. In particular it allows the farmer to let weeds grow in the field early on during the growing season, knowing that he has an effective herbicide that he can apply later in the year without harming his crops.

All these crops received regulatory approval – both with regard to human health and environmental effects – by 1998. But during the heated GM debates of the late 1990s, English Nature, a statutory conservation body, pointed out that nobody had taken into account the potential impact, not of the crops themselves, but of the farmers’ weed management practices associated with the new crops.

Would the farmers actually delay the application of herbicides, thus improving the lot of the species that feed on the weeds, with positive knock-on effects up the food chain and for biodiversity? And even if they did, would the positive environmental impacts be outweighed by the negative impacts on biodiversity of more effective weed control later on in the growing cycle? These were the sorts of questions the farm-scale trials were designed to address.

At a summary level, the answers the Scientific Steering Committee for the trials has come up with seem relatively straightforward. ‘Growing conventional beet and spring rape was better for many groups of wildlife than growing GM herbicide-tolerant (GMHT) beet and spring rape. Some insect groups, such as bees (in beet crops) and butterflies (in beet and spring rape), were recorded more frequently in and around the conventional crops because there were more weeds to provide food and cover.… In contrast, growing GMHT maize was better for many groups of wildlife than conventional maize. There were more weeds in and around the GMHT maize crops, more butterflies and bees around at certain times of year, and more weed seeds.’

Simplistically then, a thumbs-up for GMHT maize and a thumbs-down for beet and spring-sown rape.

However, life on a farm is more complicated than that. As Michael Crawley from Imperial College told the Royal Institution audience on 16 October, if commercial planting of these crops were allowed, who’s to say which farmers would use them and what management practices they would adopt? Would it primarily be farmers who currently manage their farms to minimise weeds anyway who adopt these new crop varieties, or would there be a high take-up among farmers with weedier fields? The implication was that the latter scenario would have a greater impact on the amount of weeds found on British farms and on the wildlife that lives off them.

When it comes to weeds and wildlife the picture isn’t simple either. For example, while the scientists found fewer bees and butterflies in the GMHT beet crops than in the conventional varieties, they also point out that ‘there are never many bees and butterflies in beet crops’. Apparently ‘researchers were often comparing counts of only two or three bees per field’. They found ‘more bumble bees feeding on weeds growing in margins of the beet and maize fields than in the fields themselves’, and ‘no differences in the number of bumble bees on margins of conventional or GM crops’ for all three types of crop studied – beet, maize and spring rape.

They also found ‘at least five times as many bumble bees in the fields of spring rape crops (both GMHT and conventional) than in the beet or maize crops’ and said ‘it looks likely that bumble bees will be more affected by the proportion of farmland growing different crops than whether fields contain conventional or GM crops’. So if we want more bumble bees at least, it sounds like we should grow more rape and not worry about GM or not GM.

When it came to butterflies, while researchers found significantly lower numbers around the field margins of GMHT spring rape and beet compared to the conventional varieties (though little difference between GM and conventional maize), the picture is apparently complicated by the high mobility of butterflies and their ability to fly on until they find the plants they need elsewhere.

Moving on to the less cute ‘soil-surface-active-invertebrates’ (beetles, spiders and the tiny springtails found in the soil), the picture at a general level seems quite positive. The tiny springtails (maybe two millimetres long) that break down dead vegetation and return nutrients to the soil were more abundant in the fields of all three types of GM crops – possibly because delayed use of herbicides meant the weeds grew larger before being killed, hence providing a greater source of food to the springtails.

And as David Brooks and Alison Haughton from Rothamsted Research told us, in general there were no significant differences between GM and non-GM for any of the crop types as far as abundance and diversity of beetles and spiders was concerned – though specific species of each fared better or worse in response to the new management practices.

I found the presentations given by the scientists very interesting. That said, they have not changed my long-standing belief that the farm-scale trials have no relevance to the decision about whether the UK should experiment commercially with GM crops, or whether it should keep farms GM-free. This bizarre how-many-butterflies-on-a-beet-leaf debate is clearly not what the GM issue is about – whatever side you take on it.

The opposition to GM crops in the UK is more political than it is scientific. It is based on a one-sidedly negative account of modern agriculture, scientific and technological experimentation and the track record of big business and government. GM, like any other agricultural technology, is bound to have some kind of impact upon the weeds and insects found in crops – indeed, this is the point of it.

The fact that this impact has been widely reported as proof of environmental ‘damage’ indicates that any attempt by farmers to use technology to improve farming practices today tends to be seen in a negative light. The most important question at stake in the GM issue – whether the application of this technology is good for humanity – cannot be resolved at a technical level and certainly not by counting beetles and weeds.

It is the broader mistrust of modern farming, and the negative sentiments that lie behind it, that the UK government has consistently found itself unable to challenge. To date, the government has hidden behind a combination of waiting for the results of the farm-scale trials, a technical cost-benefit analysis exercise, calls for more scientific research and regulation, and a rather lame public consultation exercise in the vague hope that a decision to move ahead with GM technology might eventually become possible without it having to win any difficult political arguments or to counter the cynicism of our times with a positive, progressive vision of the future.

UK environment secretary Margaret Beckett gave a predictably bland response to the farm-scale trials. ‘I shall reflect carefully on these results and the outcome of the public debate. I have said consistently that the government is neither pro- nor anti-GM crops – our overriding concern is to protect human health and the environment, and to ensure genuine consumer choice,’ she said. And it has been reported today that ministers are likely to delay any decision on the commercial planting of GM crops until after the general election. It seems that the government is no more prepared to win the political arguments than it was when it conceded to the farm-scale trials four years ago, to buy itself more time.

Tony Gilland is science and society director at the Institute of Ideas. He is the editor of Science: Can You Trust the Experts?, Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)); Animal Experimentation: Good or Bad?, Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)); and Nature’s Revenge?: Hurricanes, Floods and Climate Change, Hodder Murray, 2002 (buy this book from Amazon (UK) or Amazon (USA)). He is also a contributor to Rethinking Risk and the Precautionary Principle, Butterworth-Heinemann, 2000 (buy this book from Amazon (UK) or Amazon (USA)).

Read on:

spiked-debate: The future of GM – why do we need the UK farm-scale trials? (September to October 2002)

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Topics Science & Tech


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