A European study into the effects of pesticides on bee colonies has shown a conclusive link between the use of certain chemicals and bee population decline.
The study, carried out by the Centre for Ecology & Hydrology (CEH) in Oxfordshire, investigated the effects of neonicotinoid pesticides on bees in three countries.
Specifically, the study looked at the effect of winter oilseed rape crops treated with seed coatings containing neonicotinoid clothianidin, from Bayer CropScience, or Syngenta’s thiamethoxam on bee colonies nearby.
Examining the effects of the pesticides in the UK, Germany, and Hungary the study showed that the use of these pesticides reduced the chances of bees surviving the winter in 2 of the countries.
“The neonicotinoids investigated caused a reduced capacity for all three bee species to establish new populations in the following year, at least in the UK and Hungary,” said Dr. Ben Woodcock from CEH.
Notably, these negative effects were present not just in managed honeybee colonies, but also in wild bee populations.
The bee hives in Germany, however, saw little impact from the use of the pesticides, a fact which the researchers believe is explained by the greater availability of wildflowers in this area.
Despite Germany acting as an outlier, lower reproductive success was linked with increasing levels of neonicotinoid pesticide residues in the hives of several wild bee species across all three countries.
Unlike previous studies which had been inconclusive on the effects of these pesticides, this wide-scale research project was conducted in a way which attempted to, as best as possible, mirror real-world conditions.
The researchers suggested that this approach could be used for the testing of new pesticides that are coming onto the market.
“Our findings also raise important questions about the basis for regulatory testing of future pesticides,” said Professor Richard Pywell, also involved in the CEH project.
Interestingly, both Syngenta and Bayer partially funded the CEH research, however, they did not design the study itself. Each company has since put out statements saying that they disagree with the findings of the study.
Neonicotinoid pesticides are already under a temporary ban in the EU, which has been in force since 2013. A wider ban is expected to be passed this year.