An international panel of scientists is calling for an evidence-driven debate over whether a widely used type of insecticide is to blame for declines in bees and other insect pollinators.

An EU ban on certain neonicotinoid insecticides was introduced in December 2013 because of fears they are harming pollinating insects. Pollination by insects is critical for many crops and for wild plants but at the same time neonicotinoids are one of the most effective insecticides used by farmers. Potential tensions amongst the agricultural and environmental consequences of neonicotinoid use have made this topic one of the most controversial involving science and policy.

A restatement of the scientific evidence on neonicotinoids has been published in Proceedings of the Royal Society B. The restatement, from a group of nine scientists led by Professor Charles Godfray and Professor Angela McLean of the Oxford Martin School at Oxford University, clarifies the scientific evidence (in there view) available on neonicotinoids, to enable different stakeholders to develop coherent policy and practice recommendations. (There still is no agreement on the scientific evidence pro or con.)

Professor Charles Godfray said: “Pollinators are clearly exposed to neonicotinoid insecticides, but seldom to lethal doses, and we need a better understanding of the consequences of realistic sub-lethal doses to the insect individual, bee colony and pollinator population.”

Professor Angela McLean added; “A major question to be addressed is what farmers will do now that they face restrictions on the use of neonicotinoids. Will they switch to crops that need less insecticide treatment or might they apply older but more dangerous chemicals?”

The restatement describes how much insecticide is present in a treated plant and how much is consumed by pollinators. It goes on to summarise how neonicotinoids affect individual bees and other pollinators, and the consequences at the colony and population levels.

In reaction to this study, Professor Ian Boyd, Chief Scientific Advisor at Defra, said: “It is essential that policies on the use of pesticides are built on sound scientific evidence. This paper provides an independent assessment of this subject, which will provide clarity and authority in order to help people make more informed choices."

Paul de Zylva, from Friends of the Earth, commented: “This project is an important step toward much needed public and scientific debate and scrutiny. The Government should support and fund both more open science and safer ways to grow crops as part of its National Pollinator Strategy due in July.”

Key facts:

Since their introduction in the 1990s, the use of neonicotinoids has expanded so that today they comprise about 30% by value of the global insecticide market.

Insects are important for pollinating many UK crops, including strawberry, raspberry, apple, pear, plum, tomato and many vegetables.

The populations of both managed honeybees and wild pollinators were declining before the widespread use of neonicotinoids, with habitat change and honeybee disease thought to be particularly important causes.

A series of experiments have raised the possibility that widespread neonicotinoid use may exacerbate pollinator decline, though other studies find fewer effects of the insecticide.

Background

The paper (Proc. R. Soc. B 20140558) and electronic supplementary material is open access and available at http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2014.0558;

This summary is the second in a planned series of “restatements”, part of a project led by Professors Angela McLean & Charles Godfray from the Oxford Martin School at the University of Oxford. They are designed to help policy-makers access scientific evidence in controversial topics. To do this, a group of respected scientists who represent the range of views on a particular topic are convened. They together write the “restatement” of the evidence. The restatement is a series of paragraphs designed to be: concise and jargon-free, as policy neutral as possible, and each assigned a score denoting the strength and nature of the underlying evidence. Before publication each restatement is sent to a large number of interested parties and the group prepares the final version in the light of their comments.

Also taking part in the project were: Tjeerd Blacquière from Wageningen University and Research Centre, the Netherlands; Linda Field from Rothamsted Research; Rosemary Hails and Adam Vanbergen from the NERC Centre for Ecology and Hydrology; Gillian Petrokofsky from Oxford University; Simon Potts from Reading University and Nigel Raine from the University of Guelph, Canada.

The EU has banned the use of three types of neonicotinoids on crops attractive to bees for a minimum of two years.

Defra is the UK’s Department of the Environment, Food and Rural Affairs.