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UK study casts doubt on link between insecticide and bee declines

Research from the UK Food and Environment Research Agency (FERA) has cast doubt on links between bee population declines and a class of insecticides called neonicotinoids.

‘Neo-nics’ have been a controversial topic of late. In January, Europe’s food-safety body said that they may pose a risk to honeybees, but an attempt to ban the use of three such compounds — clothianidin, imidacloprid and thiamethoxam — across the European Union hit roadblocks this month when it was rejected in a vote by member states. Campaigners hope that ending the use of these compounds could help to arrest declines seen in some bee populations across the globe.

Now, a field trial run by FERA, based in Sand Hutton, has failed to find any “clear consistent relationship” between neonicotinoid residues and the size of bumblebee colonies or the number of new queens they produce. “The absence of these effects is reassuring but not definitive,” says the FERA study, which involved assessing the health of colonies near crops grown from seeds that were treated with clothianidin and imidacloprid.

A related publication, also released this week, by the UK Department for Environment, Food and Rural Affairs (DEFRA), which funds FERA, summarizes the data and concludes that there is a “growing body of evidence” that neonicotinoids do not exert an effect under conditions where bees can forage naturally. This suggests that studies in the laboratory that have linked the insecticides to an impact on bee health at less-than-lethal doses “did not replicate realistic conditions, but extreme scenarios”, says the DEFRA report, which summarizes evidence on the purported link.

DEFRA’s conclusion is likely to prove highly controversial. Campaigners have been pushing for Europe to enact a ban on neo-nics and have condemned the UK government for not supporting this.

In a recent World View in Nature, Lynn Dicks, a conservation researcher at the University of Cambridge, UK, wrote:

There is no doubt that the proposed restriction on the use of these neonicotinoids on nectar- and pollen-rich crops such as oilseed rape will reduce a potentially serious risk to bees. It seems a crucial step towards reversing or halting observed declines in bees and other flower-feeders. But that is not enough for some environmental campaigners, who have framed the problem as one of the very survival of an unspecified number of bee species. Two and a half million people have signed an online petition telling EU decision-makers: “If you act urgently with precaution now, we could save bees from extinction.”

The assertion that a ban on neonicotinoids in Europe will save bees from extinction is absurd. There are bee species around the world in genuine danger of extinction, such as the once-common rusty-patched bumblebee in the United States, which has vanished from 87% of its historic range since the early 1990s. Diseases, rather than pesticides, are suspected of driving that decline. And although there have been dramatic falls in the numbers of managed honey bee Apis mellifera colonies in some countries, it remains a widespread and common bee, not in imminent danger of extinction.


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