Two new farm-based studies have provided some of the most compelling evidence to date that neonicotinoid pesticides are harmful to domestic and wild bees.
The first study, paid for in part by $3 million from Syngenta and Bayer and published in the journal Science, “took place at 33 large farmland sites spread across the UK, Germany and Hungary. Honeybees, bumblebees and solitary bees living by insecticide-treated fields of oil seed rape were compared with those in fields where insecticides were not used in the year of the study,” says The Guardian.
The researchers saw a higher mortality rate in honeybee colonies in the UK and Hungary, but not in Germany, where the bees foraged less on heavily-sprayed oil rapeseed. Wild-bee mortality also increased as the use of neonicotinoids spread in all three countries during the study.
“We showed significant negative effects at critical life cycle stages,” said Prof Richard Pywell, from the UK’s Centre for Ecology and Hydrology (CEH), and part of the research team. “If the bees are foraging a lot on oil seed rape, they are clearly at risk. This is a large and important piece of evidence, but it is not the only evidence regulators will look at.”
However both Syngenta and Bayer disputed the findings, claiming that the results were a “simplistic” analysis of complex and “inconsistent” data, says The Guardian.
“We do not share CEH’s interpretation and remain confident that neonicotinoids are safe when used responsibly,” said Richard Schmuck, director of environmental safety at Bayer CropScience.
The second study, conducted on corn farms in Canada, found that “crops were not the main source of neonicotinoids to which bees were exposed. Instead, the contaminated pollen came from wildflowers, as has been shown recently in the UK,” says The Guardian. The study also discovered that neonicotinoids used in conjunction with anti-pest fungal treatments were even more harmful to bees.