Insecticides blamed for bee decline

Worldwide declines in bee colonies, threatening much of global agriculture, may be caused by a new generation of nerve-agent pesticides, two new studies strongly suggest.

The findings place a massive question mark over the increasingly-controversial compounds, now the fastest growing family of insecticides.

Bees pollinate a large percentage of crops. Both honeybees and wild bumblebees are seriously harmed by exposure to neonicotinoid insecticides, even by tiny doses not sufficient to kill them outright, the studies by British and French scientists report.

About 30 per cent of British cropland – 3.14 million acres – was being treated with the chemicals in 2010.

The compounds, which attack insects' central nervous systems, have been increasingly implicated in the widespread declines of honey bees and wild bees over the last decade.

In France, Italy and other countries the new pesticides have been banned, but not in Britain and the US.

The findings, published in the journal Science, are explosive.

The British study, led by Stirling's Professor David Goulson, Britain's leading bumblebee expert, showed that growth of colonies of the common buff-tailed bumblebee, slowed after the insects were exposed to "field-realistic levels" of imidacloprid, a common neonictonioid insecticide. In particular, the production of queens declined by a massive 85 per cent in comparison with unexposed colonies used as controls.

Queen bumblebees are essential for colonies to continue as only they live through the winter. The study concludes that "there is an urgent need to develop alternatives to the widespread use of neonicotinoid pesticides on flowering crops. whenever possible".