An important new study about the effects of neonicotinoid pesticides on wild bees has just been published in the journal Nature Communications – here’s the details and a link to the paper, which is open access:

Woodcock, B. A. et al. (2016) Impacts of neonicotinoid use on long-term population changes in wild bees in England. Nat. Commun. 7:12459 doi: 10.1038/ncomms12459

As I’ve previously discussed on this blog (e.g. here and here) there are widespread concerns amongst environmentalists, and some scientists, about the impact that these relatively new pesticides are having on pollinators and other biodiversity.  The Woodcock et al. paper is a major contribution to this discussion as it uses a huge dataset to model the changes in populations of 62 wild bee species that are known to forage on oilseed rape (canola) over 18 years.  These changes can be related to the spatial extent of oilseed rape cultivation and the authors found that whilst bees “….foraging on oilseed rape benefit from the…[nectar and pollen provided by]….this crop….[they]….were on average three times more negatively affected by exposure to neonicotinoids than…” bees which didn’t forage on the crop.

The authors further conclude that “This study provides the first evidence for community level national scale impacts on the persistence of wild bee populations resulting from exposure to neonicotinoid treated oilseed rape crops.”

Neonicotinoid pesticides are, of course, not the whole story when it comes to understanding declines in pollinator diversity and abundance.  But these pesticides are the latest in a long history of changes to British agriculture that have had significant consequences for the biodiversity of our country (as we showed in our study of bee and wasp extinctions).

Reactions to the study have been, well, predictable.  A long feature on the BBC News website* quoted a representative from Bayer as saying:

“we believe….[the study’s]….findings would be more correctly headlined that intensive agriculture is causing some issues with pollinators…..  Whether this is due to the use of insecticides is not clear; a lack of nesting sites and pollen and nectar sources in these areas may also be critical factors.”

Which rather ignores the fact that this was a comparative study of bees that forage on oilseed rape versus those that don’t.

Likewise the National Farmer’s Union’s position was that:

“While this study claims to provide an important contribution to the evidence base underpinning the current EU moratorium on some uses of neonicotinoids, experts reviewing all the evidence have concluded that there are still major gaps in our knowledge and a limited evidence base to guide policymakers”

Which sounds to me like a statement designed to fudge the issue: the “experts reviewing all the evidence” would not have reviewed this particular study!  And which begs the question – how much evidence and how many studies would be enough for the NFU?

The study’s authors do not make any suggestions as to what the next step should be in this continuing saga but are quoted as saying that “simplistic solutions” such as banning these pesticides are not the answer because this will encourage use of pesticides that are even more damaging.  That may be the case but it’s clear that an independent root-and-branch reassessment of the use of pesticides (and herbicides) in UK agriculture is long overdue.

*As an aside, this BBC News piece wrongly states that bumblebees were not included in the study, which is not the case.

UPDATE:  After I published this post I noticed that Manu Saunders has also written about the bee study, plus a second study that I’d not seen linking neonicotinoid use to declining butterfly populations in California.  Here’s a link to Manu’s blog.