Bees may get an extra buzz from neonic insecticides

Bees may be attracted to crops, such as oilseed rape, that have been treated with banned neonicotinoids, according to one of two reports that both claimed the pesticides are harmful to bee colonies.

An insect neuroethologist team from Newcastle University has found that bees may actually prefer nectar from crops that has been treated with one of three neonics currently banned.

Meanwhile, a Swedish study showed wild bee densities in neonic-treated oilseed rape fields were only half of those in untreated fields.

The EU banned three neonics – clothianidin, imidacloprid and thiamethoxam – in December 2013 after allegations they were harmful to bees, although some have claimed that many studies have used unrealistic pesticide doses.

See also HGCA says 3.5% of English oilseed rape lost to flea beetle

Geraldine Wright and her colleagues at Newcastle confined bumblebees and honeybees to boxes with natural nectar and nectar treated with the three neonics.

They found that “honeybees and bumblebees do not avoid nectar-relevant concentrations of three of the most commonly used neonicotinoids” and most crucially “both species prefer to eat more of solutions laced with imidacloprid or thiamethoxam”.

The second study, from an ecology team at Lund University in Sweden, studied bees in eight clothianidin-treated oilseed rape fields alongside eight untreated fields.

They found that wild bee densities in treated fields were half of that in untreated fields, while nest and colony growth was also reduced in treated fields.

Maj Rundlöf, who headed up the research, said: “I’m worried about the effects on wild bees” and said her study showed seed coated with a neonic “can have serious consequences” on wild bee populations.

Nick von Westenholz, chief executive officer of the Crop Protection Association, dismissed the new studies as part of an ongoing anti-neonic campaign.

“It is a shame that the debate around the use of these important technologies appears to be increasingly politicised, with anti-pesticide activists consistently promoting their agenda under the auspices of independent research,” he said.

A survey by the HGCA showed that 5% of the oilseed rape crop in England was destroyed by cabbage stem flea beetle last autumn during the first season of the ban on neonics, which were used to control the flea beetles. Some 1.5% was redrilled, but 3.5%, or 22,000ha of the crop, was lost.

Friends of the Earth’s Sandra Bell said she wants to see a permanent EU ban on the chemicals.

“The scientific evidence that neonicotinoid insecticides harm our bees keeps stacking up. These dangerous chemicals have no place on our farms,” she added.

The European Food Safety Authority is set to review new evidence this year before it decides whether to lift a ban on the three chemicals.