Scientists from Fera and the University of Exeter have come to the conclusion that neonicotinoid pesticides may not pose as great a threat to bee populations as had previously been thought. In a study, published this month in the journal Science ,researchers  suggest neonicotinoid oilseed rape pesticide Cruiser may not be responsible for colony collapse disorder in bees, though two studies published earlier in the year in Science came to the opposite conclusion.

Neonicotinoids are among the most widely-used agricultural insecticides in the World; honeybees ingest residues of the pesticides as they gather nectar and pollen from treated plants. Previous studies had shown that sub-lethal doses of the preparations caused disorientation and other harmful effects in bees, leading authors to suggest the chemical could be linked to colony collapse disorder, wherein worker bees abruptly disappear from a colony.

image expired

In response to findings from April this year, which linked thiamethoxam, the active ingredient in Syngenta’s Cruiser OSR pesticide, to colony collapse disorder, the French government banned the chemical. Italy has since followed suit and environmental activists in the UK have called on the government to introduce a National Bee Action Plan and join the French and Italian governments in outlawing the pesticide.

The week, the UK government announced it would not act on the matter, following consultation with Fera and the Health and Safety Executive.  

However, the Fera study does not suggest that pesticides are in any way harmless. It merely points out that the authors of a previous French study had not accurately calculated the rate at which honeybee colonies recover from losing individuals or expand during the spring, when oilseed rape is blossoming. Previous research, led by French scientist Mikaël Henry, showed that the death rate of bees increased when they drank nectar laced with a neonicotinoid pesticide at concentrations which they would typically find in the field, the new study does not contest this.

Clarifying the results of his research, Dr James Cresswell of the University of Exeter who led the Fera study said, “We know that neonicotinoids affect honeybees. I am definitely not saying that pesticides are harmless to honeybees, but our research shows that the effects of thiamethoxam are not as severe as first thought.”

He said that his study merely showed that “there is no evidence that [thiamethoxam] could cause colony collapse; when we repeated the previous calculation with a realistic birth rate, the risk of colony collapse under pesticide exposure disappeared.”

Nevertheless, Dr Creswell qualified his assertion by stating, “We do not yet have definitive evidence of the impact of these insecticides on honeybees and it is vital that more research is conducted so that we can understand the real impact of neonicotinoids on honeybees, so governments can put together a proper plan to protect them from any dangers that the chemicals pose.”

The study was published in Science on Thursday (20th September). Although the industrial farming lobby has given the Exeter study a hearty reception, environmental groups have drawn attention to its strict limitations. Chemical companies which manufacture neonicotinoids maintain that bee decline is the result of loss of habitat and disease, and deny that pesticide use is a contributing factor.

Friends of the Earth spokesperson Paul de Zylva commented that the only thing the Fera study shows is that “One type of neonicotinoid pesticide, thiamethoxam, does not cause springtime colony collapse disorder in honey bee populations,” which he added "does not remove the smoking gun of the role of pesticides in bee decline, and does nothing to reduce concerns that these vital pollinators are being poisoned every day.”

Mr de Zylva elaborated, "The research says one type of neonicotinoid pesticide, thiamethoxam, doesn't cause bee colonies to die off in the spring, but it doesn't rule out its role in colony collapse later in the year. Neonicotinoid pesticides cannot be given a clean bill of health until they have been properly tested for their effect on all bees, not just honeybees - until then the Government should suspend them from sale.

"Ministers must also do more to reduce our reliance on pesticides and encourage chemical-free farming and gardening. The huge decline in bee numbers is a serious threat to food production - a National Bee Action Plan is needed to tackle it."

Tweet