Two US Congressmen have launched a bill to suspend uses of neonicotinoid insecticides in the US, following the lead of the European Union. Representatives John Conyers of Michigan and Earl Bluemenauer or Oregon introduced the “Saving America’s Pollinators Act”. They were prompted by widespread honeybee colony losses and a major bumblebee kill in Oregon where 50,000 dead bumblebees were found beneath two lime trees as a result of their being sprayed with neonicotinoids for ornamental reasons (note that lime trees often have a few dead bumblebees under them for separate reasons that have never been fully explained). I was recently invited over to speak in Capitol Hill in support of this bill.   

The debate over neonicotinoids and bees rolls on and on, with new studies emerging every day. It seems to me that the evidence on bumblebees is clear and convincing - realistic doses are very likely to be doing harm to wild colonies – but the evidence for honeybees remains muddier. However, most of the studies finding no impact on honeybees have been funded by or performed by the industry that manufactures the chemicals, so murky waters are to be expected. 

My visit coincided with the launch of a fascinating review of the economic value of neonicotinoids, produced by the Centre for Food Safety, a US-based non-profit organisation. They review 19 studies that have evaluated how much neonicotinoid seed dressings (the usual way of using these chemicals) increase yield of a range of crops, including wheat, corn, soya beans, and oilseed rape. The findings are astonishing – in every case, the studies either found no benefit whatsoever, or weak and inconsistent benefits unlikely to offset the cost of the pesticide. As Dr Christian Krupke (a leading researcher on this topic at Purdue University) said to me, “There may be places in the US where the pests are so bad that farmers need neonicotinoid seed dressings, but we can’t find them”.

In short, the most widely used pesticides in the world - prophylactically applied to arable crops across the globe - appear to be ineffective, and to have been widely miss-sold. It reminds me a little of the Payment Protection Insurance scandal – farmers are advised to use seed dressings as an insurance against something which, it seems, almost never happens.

Remarkably, no similar studies seem to have ever been performed in the UK or elsewhere in Europe to evaluate how much, if at all, neonic seed dressings increase yield here. It would be easy to do – experimental plots of crops that are treated exactly the same, except for the presence or absence of the seed dressing. How did these chemicals come to be so widely used without the manufacturers demonstrating clearly that they worked? If they did perform such studies, why can nobody find them? Sceptics such as I might also point to Italy, where neonics were banned on corn some years ago and where yields have remained stable and corn farming profitable.   

For me, this turns the whole bee debate on its head. If neonic seed dressings were essential to grow crops, one might have to accept a risk of harm to bees. But it seems that they are not.

In Europe, a decision will need to be made in the next year or so as to whether the current EU moratorium is extended or allowed to lapse. This new evidence will hopefully help to prevent the latter.

Prof Dave Goulson, University of Sussex.

[An abbreviated version of this Blog is published in the newsletter of the BBKA, June 2014]