A honeybee (Apis mellifera) gathers pollen from an apple-tree flower.Credit: Solvin Zankl/NPL

In a long-awaited assessment, the European Union’s food-safety agency has concluded that three controversial neonicotinoid insecticides pose a high risk to wild bees and honeybees. The findings by the European Food Safety Authority (EFSA) in Parma, Italy, raise the chances that the EU will soon move to ban all uses of the insecticides on outdoor crops.

In 2013, the EU prohibited applications of the three chemicals on crops attractive to bees — such as sunflowers, oilseed rape and maize (corn) — after an EFSA assessment raised concern about the insecticides’ effects. Since then, researchers have amassed more evidence of harm to bees, and the European Commission last year proposed banning all outdoor uses, while still allowing the pesticides in greenhouses. The latest EFSA assessment strengthens the scientific basis for the proposal, says Anca Păduraru, a European Commission spokeswoman for public health and food safety. EU member states could vote on the issue as soon as 22 March.

Neonicotinoids (often abbreviated to neonics) are highly toxic to insects, causing paralysis and death by interfering with the central nervous system. Unlike pesticides that remain on plant surfaces, neonicotinoids are taken up throughout the plant — in the roots, stems, leaves, flowers, pollen and nectar.

The EFSA assessment covered the three neonicotinoids of greatest concern to bee health — clothianidin, imidacloprid and thiamethoxam. The agency considered more than 1,500 studies, including all the relevant published scientific literature, together with data from academia, chemical companies, national authorities, non-governmental organizations (NGOs) and beekeepers’ and farmers’ associations. The assessment found that each of the three chemicals posed at least one type of high risk to bees in all outdoor uses.

Harmful exposure

The agency found that foraging bees are exposed to harmful levels of pesticide residues in pollen and nectar in treated fields and contaminated areas nearby, as well as in dust created when treated seeds are planted. It also concluded, on the basis of more limited evidence, that neonicotinoids can sometimes persist and accumulate in the soil, and so can affect generations of planted crops and the bees that forage on them.

“EFSA’s advice is often criticized by interested parties such as NGOs and companies, but this is a good demonstration of how EFSA gives scientifically sound and impartial advice,” says José Tarazona, head of the agency’s pesticides unit.

A spokesperson for the global biotechnology firm Syngenta, which produces neonicotinoids, says that EFSA’s conclusions are overly conservative. “When regulators make decisions about crop-protection products, what should matter is science, data and that the processes in place are respected and that the public interest is served,” the spokesperson says. “Any further restrictions based on this report would be ill-conceived.”

EU member states were scheduled to vote on the proposal to outlaw outdoor uses on 13 December, but postponed it partly because many wanted to wait until EFSA completed its evaluation.

Member states plan to discuss the EFSA assessment at a meeting of the commission’s Standing Committee on Plants, Animals, Food and Feed sometime in March, says Păduraru. “The protection of bees is an important issue for the commission since it concerns biodiversity, food production and the environment.”