New research published in a Nature journal has provided yet more evidence of neonicotinoids’ health impacts on bees.

The research, from Royal Holloway University in London and the University of Guelph, Canada, shows that bumblebee queens exposed to neonicotinoid thiamethoxam (one of three partially banned pesticides in the family) were 26% less likely to start a new colony. Researchers said their findings had implications for bee decline, which is a serious problem across the northern hemisphere. They suggested exposure to the controversial pesticide “Could lead to collapses in wild bee populations.”

The findings follow a major field study conducted across three European countries, results from which were published in June. Researchers from the UK’s Centre for Ecology and Hydrology (CEH), who led the research, linked increasing neonic residues in the nests of wild bees with lower reproductive success across all three countries and concluded that exposure to treated crops reduced overwintering success of honeybee colonies in the UK and Hungary. The study was publicly funded in part, with pesticide manufacturers paying for the research on honeybees; on the release of CEH’s findings, the companies that backed the research rejected its conclusions, and tried to focus on the results from Germany, where there were fewer reported health impacts on bees studied.

Though research has tended to focus on bees - and until recently only on honeybees, which are domesticated and more easily studied - there have been suggestions that systemic insecticides like neonicotinoids could be having a much broader effect on other insects and aquatic life. Commenting on the findings, Professor Nigel Raine, formerly of Royal Holloway and now at the University of Guelph, said, “This research shows that these pesticides can have a devastating effect on bees, and we urgently need to know more about how pesticides could be affecting other species.”

Professor Vincent Jansen, from Royal Holloway, added, “Neonicotinoids are the most widely used class of pesticide in the world. It is vital that we understand the effects of these pesticides on our wildlife before allowing their continued use.”

Dr Peter Campbell, Senior Environmental Risk Assessor at Syngenta (which manufactures the neonic thiamethoxam, and backed the CEH study, but accused researchers of misrepresenting their findings once it was published), said, “Although the laboratory experiment in this study reports a 26% reduction in the proportion of queens exposed to thiamethoxam that laid eggs, it must be noted that this study was carried out under artificial laboratory conditions, where the forced exposure period was 14 days. The authors themselves point out that to extrapolate this result to field populations ‘the experimental procedure…would ideally be carried out on populations in the field.’”

Dr Campbell continued, “There are some interesting data and insights presented in this paper but great care needs to be taken in extrapolating the results and predictions from this combined laboratory experiment / probabilistic modelling approach to the performance of real bumble bee queens and populations in the field, particularly when there is little evidence to show that Bombus terrestris populations are actually on the decline.”

Nevertheless, Friends of the Earth repeated its demand that the UK government backs the European Commission in its expected moves to extend neonicotinoid restrictions to all crops this year, and that ministers commit to keeping any ban post-Brexit.

Responding to the Holloway research, Friends of the Earth spokesperson Sandra Bell said, “This new study comes hot on the heels of the largest field trials of neonicotinoids showing harm to honey bees and wild bees.  It also follows new evidence of how these pesticides leak into the environment and turn up in wildflowers posing further risk to bees.

“It is clear that use of these chemicals on any crop poses a risk to bees and other wildlife. The Government has repeatedly said it will follow the science – how much more science does it need before it acts to protect our precious bees?

“Michael Gove must put his support behind a comprehensive ban on neonicotinoid pesticides across the EU and continue the ban in the UK post-Brexit.”

On 20th July, Defra Parliamentary Under-Secretary Lord Gardiner suggested that the government’s stance on neonicotinoids is beginning to change in the wake of the CEH’s major outdoor study. Answering a Parliamentary question from Green Party peer Baroness Jones, Lord Gardiner said, “Decisions on the use of pesticides should protect people and the environment and should be based on a careful scientific assessment of the risks. Pesticides that carry unacceptable risks to pollinators should not be authorised.”

Whereas Defra has previously rejected the science underpinning EU restrictions, and Lord Gardiner has said in earlier statements that the department has merely been conforming to EU regulations, the environment department’s spokesperson in the Lords said in July, “The Government keeps the developing evidence on neonicotinoids under review, advised by the UK Expert Committee on Pesticides. On the basis of current available evidence, we support the existing restrictions.”