5.8 MYTH:

GM crops help biodiversity


The herbicides used with GM crops harm biodiversity

“Many farmland birds rely on seeds from weeds for their survival and the [UK] government’s farm scale trials showed that GM beet and GM spring oilseed rape [canola] reduced seed numbers by up to 80% compared with conventional beet and oilseed rape. The commercialisation of GM beet and oilseed rape could be disastrous for birds. The government is committed to reversing bird declines and has promised to ban GM crops if they damage the environment. The Farm Scale Evaluations (FSEs) show that two GM crops harm the environment and ministers now have no choice but to refuse their approval.”
– Dr Mark Avery, director of conservation at the UK’s Royal Society for the Protection of Birds (RSPB) and member of the UK government’s Science Review Panel116

In the early 2000s the UK government conducted three-year farm-scale trials to examine the impacts of managing GM herbicide-tolerant crops (maize, sugar beet and canola) on farmland biodiversity. Each field was divided in half, with one half planted with a non-GM variety managed according to the farmer’s normal practice, and the other half planted with a GM herbicide-tolerant variety. The GM beet was tolerant to the glyphosate-based herbicide Roundup and the GM maize and canola were tolerant to glufosinate ammonium. The herbicide-tolerance genes enabled farmers to spray the crops with these broad-spectrum (kill-all) herbicides, killing all weeds but allowing the crop to survive.

Weeds provide food and habitat for birds, insects, and other wildlife, so the farm-scale trials recorded levels of weeds and invertebrates in the fields and field margins. Selected groups of other organisms with wider foraging ranges (beetles, bees, and butterflies) were also studied. The trials looked at whether the changes in management associated with GM crops would reduce weed levels and have wider impacts on farmland biodiversity.

The findings showed that the cultivation of GM herbicide-resistant crops reduces wildlife populations and damages biodiversity, due to the effects of the broad-spectrum herbicides with which they are grown.117,118,119,120,121,122

GM herbicide-resistant maize was found to be better for wildlife than non-GM maize, with more weed species and insects in and around the field.117,118,119,120,121,122 But the GM maize was measured against a non-GM maize grown with atrazine, a toxic herbicide that was banned in Europe soon after the trials ended. With such a toxic control, it was highly likely that the GM maize would be found to be better for wildlife.A more useful comparator would have been a maize grown in an organic or integrated pest management (IPM) system, which eliminate or reduce herbicide use.

In the EU, this is not a purely idealistic notion. A 2009 European Directive asks member states to implement national plans to adopt integrated pest management and alternative approaches in order to reduce pesticide use.123

  • For references, please click here.
  • Download a PDF of the full GMO Myths and Truths report
  • We work hard to bring you reports backed up by strong science.
    Please help us by supporting our work.
    Donate button

Add comment

Security code