Is agriculture's toxic hold turning into a death grip?
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- Published on Thursday, August 14, 2014
By Larry Powell
This summer the tragedy of dying pollinators took on a new dimension. A team of Dutch researchers found that, in addition to bees, "significant declines in populations of insect-eating birds are also associated with high concentrations of neonicotinoids."
"Neonics," as they're commonly called, have become the most widely-used group of insecticides in the world — and the most infamous. As well as killing the crop pests they're supposed to, they've played a role in the deaths of billions of honeybees from near and far, for well over a decade. The European Union even clamped a two-year moratorium on their use last year.
Various formulations of the chemical are made by multinational corporations like Bayer CropScience, Syngenta and Monsanto. They're used as a seed dressing on crops ranging from canola, soy and corn to potatoes. Bayer advertises them as being effective in killing many pests like aphids, flea and potato beetles. They are "systemic" poisons which means they penetrate all parts of the plant, even the nectar and pollen. But as little as two per cent of the active ingredient is taken up by the plant. The rest gets washed off, contaminating both soil and water. Neonic use exploded onto the farm scene about two decades ago, on crops that now cover vast areas of the world's farmlands.
The study, by scientists at Radboud University, was published in the journal, Nature. It concludes the most widely-used neonic, imadacloprid, poisons not only insects harmful to the crops, but others which form an important part of birds' diets, especially during the breeding season and while raising their young. These would include grasshoppers, butterflies, caterpillars, mosquitoes, midges and mayflies.
"In the Netherlands, local (bird) population trends were significantly more negative in areas with higher surface-water concentrations of imadacloprid. At concentrations above 20 nano grams per litre, bird numbers tended to decline by 3.5 per cent on average, annually. These declines appeared only after the introduction of imadacloprid to the Netherlands in the mid-1990s. Our results suggest that the impact of neonicotinoids on the natural environment is even more substantial than has recently been reported and is reminiscent of the effects of persistent insecticides in the past."
This is an apparent reference to DDT, another persistent insecticide. It was banned in North America after Rachel Carson's book, Silent Spring, came out in the 1960s. It exposed DDT as being harmful to birds, fish and human tissue.
Birds are much less vulnerable to neonics than insects. So it's believed their numbers are declining not because of direct poisoning, but because the chemicals are killing off the insects they normally eat. But it's also unlikely any bird that directly eats seed treated with neonics will stand a chance.
One study concludes, "A single corn kernel coated with a neonicotinoid can kill a songbird." Another finds, "Consumption of small numbers of dressed seeds offers a route to direct mortality in birds." And some of the bird species included in the Dutch study, like starlings and skylarks, eat grain as well as insects.
Is this just a "far away" problem? Not really!
Last winter, a biologist at University of Saskatchewan sounded a very similar alarm. Christey Morrissey is about halfway through a four-year study of the chemicals in question. She told CBC huge amounts of neonics are leaching into millions of potholes which dot the landscape of the Canadian Prairies. This can have potentially devastating impacts on aquatic insects such as mosquitoes and midges, both important food sources for birds. She says levels of the poison in the water have been found to be anywhere from 10 to 100 times above limits which are considered safe. Meanwhile, she notes, populations of insect-eating birds such as the barn swallow, have plummeted some 70 per cent over the past 30 years. She concedes that other factors, like habitat loss, are contributing to the decline. But she still believes neonics are playing a significant role.
The Dutch study team offers this guidance for policy-makers: "Future legislation should take into account the potential cascading effects of neonicotinoids on ecosystems."
Morrissey made this observation on CBC: "We all want to have food that we consume and enjoy. But at what cost? Is that at the cost of having no more birds around? Of having no more butterflies? Having no bees? People are thinking about that now."
