Neonicotinoids pose 'low' risk to bees, Defra studies show
DEFRA has published two pieces of research suggesting the risk of neonicotinoids seed treatments to bee populations in the field is low.
The two pieces of research, including a field trial from the Food and Environment Research Agency (Fera), contradict the findings of an EU risk assessment and are likely to reinforce the UK’s opposition to a proposed EU ban.
The European Commission is planning to suspend the use of three neonicotinoid products - imidacloprid, thiamethoxam and clothianidin - for two years from as soon as this July.
The proposal is based on the findings of a risk assessment by the European Food Safety Agency (Efsa), which found the chemicals, which are used to treat seeds prior to sowing to protect against insects like aphids, pose a ‘high risk’ to honey bees from crops producing nectar and pollen.
But Defra abstained from a key vote on the chemical treatment in Brussels last week. Ministers said the UK would reserve judgement until Defra had completed its own assessment of field studies on the possible risk.
On Tuesday, Fera published the results of its field trials that examined bee colonies on three sites sown with oilseed rape – one planted with untreated seed, one clothianidin-treated seed and the other where imidacloprid had been used.
The Fera report said ‘no clear consistent relationships were observed’ between the variation in neonicotinoid residues across colonies within and between sites and colony mass and the number of new queens produced.
It concluded the absence of these effects was ‘reassuring’ but did not constitute ‘definitive’ proof as the study was not a formal statistical test of the hypothesis s that neonicotinoids reduce the health of bumble bee colonies.
“Nevertheless, were neonicotinoids in pollen and nectar from treated oilseed rape to be a major source of field mortality and morbidity to bumblebee colonies, we would have expected to find a greater contribution of insecticide residues from nearby treated crops and for there to have been a clear relationship between observed neonicotinoid levels and measures of colony success,” the report said.
On Wednesday, Defra published an assessment of various other pieces of research carried out on the subject.
It concluded that various laboratory studies that showed a negative impact on bee healthy were not fair accounts of what happens in the field due to the ‘overdosing of bees’ in these studies.
“In all cases there is evidence that the doses of neonicotinoids presented to bees under laboratory or semi-field conditions were unrealistically high. The dosing studies therefore represented the extreme case in a field situation,” the Defra study said.
It added accumulated evidence across several independent field studies suggests ‘any effects that are present are likely to be small and not biologically significant’, although it acknowledged these studies ‘might not have the statistical power to show effects’.
It said the fact that OSR treated with neonicotinoids has been a productive crop for over a decade in the UK is itself evidence that pollinator populations, including bees, are not being reduced by the presence of neonicotinoids as OSR requires insect pollinators.
“While this assessment cannot exclude rare effects of neonicotinoids on bees in the field, it suggests that effects on bees do not occur under normal circumstances. Consequently, it supports the view that the risk to bee populations from neonicotinoids, as they are currently used, is low,” the study concluded.
Speaking in the House of Commons on Tuesday, Farming Minister David Heath said the Defra research showed no link between the chemicals and bee health under normal circumstances. He said the Government would only wish to restrict used of the chemicals ‘if evidence shows the need’ and that it has urged the Commission to be ‘proportionate’ and take into account the UK findings.
Defra Chief Scientist Ian Boyd said: “Decisions on the use of neonicotinoids must be based on sound scientific evidence. The analysis of laboratory studies published by Defra today demonstrates that while we cannot rule out the possibility of neonicotinoids affecting pollinators we cannot be clear as to the extent of their impact.
“I therefore support the conclusions of the analysis that further data based on more realistic field trials is required.”
Emma Hockridge of the Soil Association said Defra was ‘relying on limited trials, rather than a whole range of studies which are showing harm to bees’.
She pointed to a separate study, published on Wednesday, which conluded that a combination of pesticides, including neonicotinoids, negatively affects the brains of bees.
“As we continue to see consistent evidence signalling neonicotinoids should be banned, we call on the UK Government to vote to ban a number of neonicotinoid pesticides as is currently being discussed in the EU.”
Friends of the Earth Nature Campaigner Sandra Bell added the study did not counter the ‘comprehensive review of the impact of neoniocotinoid insecticides on bee populations recently conducted by European scientists’.
She said: “Defra has admitted to problems with its new study, but bee health is far too urgent to wait until more research has been completed – restrictions should be placed on these pesticides until bee safety can be assured.”