A new study provides the first evidence of a link between neonicotinoid pesticides and escalating honeybee colony losses on a landscape level.
The study found the increased use of a pesticide, which is linked to causing serious harm in bees worldwide, as a seed treatment on oilseed rape in England and Wales over an 11 year period correlated with higher bee mortality during that time.
The research, published in Nature scientific reports on Thursday, combined large-scale pesticide usage and yield observations from oilseed rape with data on honeybee loses between 2000 and 2010.
The total area of land planted with oil seed rape in England and Wales more than doubled from 293, 378 hectares (724,952 acres) to 602,270 hectares over that time and the number of seeds treated with the imidacloprid pesticide increased from less than 1% of the area planted in 2000 to more than 75% of the area planted with oilseed rape by 2010.
Comparing the pesticide usage data with honeybee colony losses, scientists led by Giles Budge at the Food and Environment Research Agency (Fera) in York - a former government agency that was outsourced to the private sector earlier this year - and US entomology professor Keith Delaplane at the University of Georgia, found a link between imidacloprid usage and honeybee colony losses. Losses varied between regions and low spring temperatures were also linked to higher bee losses in Wales.
The study, also found that famers who used seed pesticide treatments reduced the number of applications of other insecticides, but that the long-term benefits of treating oil seed rape seeds with imidacloprid on crop yields were negligible.