An extensive study on neonicotinoid pesticides has concluded that they harm both honeybees and wild bees.

The research, carried out by the Centre for Ecology and Hydrology in Oxfordshire, identified that exposure to the chemicals left honeybee hives less likely to survive over winter, while bumblebees and solitary bees produced fewer queens.The field trials were carried out at 33 sites  across the UK, Germany and Hungary.  For honeybees, the scientists concluded that in the UK and Hungary, exposure to neonicotinoids meant that hives were at risk of dying out over the winter. For bumblebees and solitary bees, the researchers said that in the UK, Hungary and Germany, higher concentrations of neonicotinoid residues found in nests resulted in fewer queens.

However Bayer and Syngenta, major producers of neonic pestcides and which part-funded the study, said the findings were inconclusive, highlighting  results in Germany  and that  if bee habitats and the health of pollinators improved “the impact of neonicotinoids can be minimal”

The landmark work provides the most important evidence yet for regulators around the world considering action against neonicotinoids, including in the EU where a total ban is poised to be implemented this autumn. The insecticides are currently banned on flowering crops in the EU.

The full results are published in Science.