Since bee colonies started declining at alarming rates over the past few decades, some scientists have identified a group of pesticides called neonicotinoids that are commonly used on crops as a potential contributor. Now one team reports in ACS' journal Environmental Science & Technology that bees could be getting an unexpected dose of neonicotinoids from wildflowers on farms. Their results suggest past studies may have underestimated the bees' exposure to these compounds.
Scientists trying to close in on the causes of bee declines have identified a mix of pressures that could be to blame. Loss of habitats, and contact with parasites and neonicotinoids all have been cited as possible factors. Past research on neonicotinoids has focused mainly on bees' exposure through crops treated with the pesticides. But because several flowering plants grow naturally on farms, and farmers often sow wildflowers near fields to attract pollinators, Cristina Botías and colleagues suspected that they could be a missing piece of the puzzle.
The researchers analyzed pollen samples from plants growing in areas close to arable fields and from beehives on five farms in the U.K. They found that pollen from wildflowers growing in these locations often contains neonicotinoid residues. In addition, 97 percent of neonicotinoids in the pollen that bees brought back to honey bee hives was from wildflowers, which were not directly treated with the pesticides. They say that neonicotinoids are likely leaching through the soil and being taken up by the nearby wildflowers. The team says their results suggest that exposure is likely to be higher and more prolonged than currently recognized.
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The authors acknowledge funding from the U.K. Department for Environment, Food & Rural Affairs and the Biotechnology and Biological Sciences Research Council (U.K.).
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