A bee expert has called into question the basis of the Government's position on neonicotinoid insecticides, saying the study it cited actually shows the chemicals to be harmful to bumblebees even in minute quantities.
In a paper published last month in the journal PeerJ, Professor Dave Goulson of the University of Sussex re-analysed a 2012 field study by the Food & Environment Research Agency (FERA).
He found a strong negative relationship between neonicotinoid contamination and both bee colony growth and queen production.
"This experiment shows that bumblebees on normal working farms in the UK are exposed to mixtures of neonicotinoids and the dose they receive is sufficient to reduce nest growth and the number of queens," said Goulson.
"Even doses of clothianidin below 0.3 parts per billion appear to be enough to do significant harm."
The original FERA report said "no clear consistent relationships were observed" between neonicotinoid residues and colony mass or the number of queens produced. Then Defra secretary Owen Paterson said at the time of its publication: "We did not see grounds for a ban based on our field trial data."
Responding to the new analysis, NFU acting chief horticulture and potatoes adviser Chris Hartfield said it added nothing to the argument over neonicotinoids. "Defra's position didn't hinge on this one piece of work, which the authors admitted had issues and was discredited by opponents of neonics at the time, so this paper adds nothing to the argument."
He added: "Other recent papers seem to back the case that neonics do not harm bees at field-level doses."
A FERA representative said: "We clearly stated that our experiment lacked the power to reach any firm conclusions about the impact of neonicotinoid-coated seed on bumblebee health. Whilst there was an absence of evidence to support the hypothesis that neonicotinoids harm bees, this does not mean that they are benign."
A Defra representative added: "We continue to work with the EU and our independent advisory committee to review any new research."
Double boost: Flower strips benefit bees
Flower strips on agricultural land not only attract bumblebees but enable their populations to grow, according to latest University of Sussex research.
A two-year study of farms in West Sussex and Hampshire by PhD researcher Thomas Wood, supervised by Professor Dave Goulson, found far higher nesting density of more common bumblebee species where bee-friendly strips had been sown under the Defra-funded Higher Level Stewardship scheme.
But there was little recorded benefit to rarer species, which tend to forage closer to nests. "The flower-rich strips on farms may be too few to benefit those species unable to cover larger distances," said Wood.