Even tiny doses of ‘neonicotinoids’ made the insects more susceptible to disease.
Pesticides are making honey bees far more susceptible to disease, according to new research than links a new group of chemicals to the recent collapse in the bee population. The US research, revealed in a new film about the disappearance of bees, found even tiny doses of ‘neonicotinoids’ made the insects more susceptible to disease.
The chemicals, that mimic the insect-killing properties of nicotine, are used widely in the UK on both ornamental garden plants and crops such as wheat and oil seed rape.
Already the bee-keeping community is divided over the use of pesticides and the study has added to calls for a ban in Britain.
Globally the honey bee population has fallen in recent years, prompting fears for food security as the insect is vital for pollinating many major crops.
However UK scientists insisted that the decline of bees is due to a number of factors, such as disease or a lack of suitable food sources in the countryside, and more research is needed before blaming pesticides.
Neonicotinoids have been widely used for at least the last ten years. The pesticide is usually applied as a seed dressing and absorbed into the plant’s whole system as it grows. It makes the plant toxic to certain insects if they eat the sap.
However scientists fear that the ‘systemic’ chemical also makes it into the plants pollen and nectar and this is affecting bees.
Research carried out by scientists at the US Department of Agriculture’s Bee Research Laboratory, revealed in new film The Strange Disappearance of the Bees, exposed two groups of bees to the common insect disease nosema. The group that was also exposed to small doses of neonicotinoids were more likely to die.
Matt Shardlow, of insect charity Buglife, said most bee deaths in the UK are caused by disease.
He said the most recent study is worrying because it suggests pesticides could be a factor in that.
While there is doubt over the use of the chemical, he suggested a ban.
“There are a number of studies which have shown that these chemicals could be the cause of the decline of bees and other wild pollinators,” he said.
However Norman Carreck, Scientific Director of the International Bee Research Association, said there is not enough evidence to link pesticides directly with the decline in bees.
“The consensus is that there is no one thing causing the decline,” he said. “Pests and disease seem to be the major factors and pesticides seems to be low down the list.”
Dr Julian Little, of Bayer CropScience, the main manufacturer of neonictinoids, pointed out the US study has not been published and peer-reviewed.
He insisted that proper scientific studies, approved by the Government, have proved that neonicotinoids do not harm bees and other insects if applied properly.
And he said the group of chemicals is much better than older versions that had to be sprayed on plants and were therefore far worse for the environment.