Long-suspected pesticide is harming bumblebees

John Dzieza, The Verge

When honey bees began dying en masse in late 2006, one of the early suspects was a class of insecticides called neonicotinoids. These chemicals are often applied to seeds before planting, so that the poison permeates the entire plant as it grows, including its pollen and nectar. The European Union placed a moratorium on the chemicals even as research results were mixed: at the doses honey bees might experience on a farm, neonicotinoids seemed to cause disorientation and a weakening of the immune system, but nothing to explain the die-offs.

Now, two studies published in Nature indicate the neonicotinoids are a problem for pollinators, though not in the way many first assumed. In the first study, researchers at Lund University looked at 16 fields of oilseed rape, a major source of vegetable oil, in southern Sweden. Half were planted with seeds coated in a neonicotinoid and a fungicide; the other half, the control, had seeds coated with only fungicide. The researchers found that placing bumblebees near the neonicotinoid-treated fields impeded the ability of colonies to grow and reproduce. Solitary bees also failed to reproduce near treated fields. The honey bee colonies, however, showed no signs of negative effects from the insecticide.

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