Keeping an eye on transgenic crops


Did you know that genetically modified, or “transgenic” crops are now commonplace on North American farms? According to a recent survey in the United States, the majority of Americans have no idea just how pervasive this technology has become. In fact, North Americans have been eating transgenic foods and using products made from their crops for over a decade. So, what kind of effect, for better or for worse, are these crops having on the environment?

One of the major concerns many ecologists had a decade ago was that transgenic organisms could inadvertently disrupt ecosystems by harming other organisms. Some transgenic crops, for example, have been engineered to resist certain types of herbicide. This allows farmers to liberally spray their fields with the herbicide, knowing it won’t harm their target crop.
These concerns were apparently warranted, as farm-scale evaluations two years ago in the UK of some transgenic crops found that vigorous application of herbicides was also damaging to the diversity of other life forms around farms. That’s because many of the weeds killed by the herbicides were important for butterflies and bees. Populations of these beneficial pollinators on the test farms fell, possibly having other, more wide-ranging implications up the food chain for birds and mammals.
Another common type of transgenic crop has an insecticide “built-in.” These crops have been genetically engineered to produce an insecticidal toxin that wards off pests. One of the most well-known has been engineered using a certain kind of bacterium called Bt. The advantage, in theory, is that Bt crops do not need to be sprayed with an insecticide to kill pests, and thus could be potentially cheaper and more environmentally friendly than their contemporary non-transgenic counterparts.
Concerns were raised, however, when lab tests showed that pollen from Bt crops could be potentially harmful to non-target insects, making them grow more slowly or reproduce less often. However a new meta-analysis of the effects of Bt cotton and Bt maize on non-target insects in the field has found that these types of crops appear, at least on the surface, to be less harmful to insects than farming methods that use insecticides.
This report, recently published in the journal Science, looked at 42 field experiments and found that fields of Bt cotton and maize contained more non-pest insects than did those that used insecticides to control pests. Of course, insecticide-free control fields still had the greatest number of insects overall. The authors point out that further studies to examine the impact on specific species of insects, rather than just all invertebrates, are essential to better understand the environmental impact of these crops.
Disturbingly, the researchers had to resort to obtaining much of their information on Bt crops through the U.S. Freedom of Information Act, because the companies that produced them did not publicly disclose it. The researchers also note that the debate around transgenic crops has been a heated and emotional one, “However, in the case of GM crops, scientific analyses have also been deficient. In particular, many experiments used to test the environmental safety of GM crops were poorly replicated, were of short duration, and/or assessed only a few of the possible response variables. Much could be learned and perhaps some debates settled if there were credible quantitative analyses of the numerous experiments that have contrasted the ecological impact if GM crops with those of control treatments involving non-GM varieties.”
Transgenic crops are not simple products like widgets, ipods or even automobiles. They are living organisms that can interact with other creatures in the environment in myriad ways. Nature is complicated. When you modify an organism at a genetic level, it shouldn’t surprise anyone that the results are also complicated, and often unexpected. Transgenic crops are, in many ways, radically new and should be subject to the greatest of scientific scrutiny, not suppressed by proprietary concerns.

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