Increased use of imidacloprid (a neonicotinoid insecticide) seed coating of oilseed rape in England and Wales between 2000 and 2010 may be linked to increases in the number of honey bee colony losses, suggests data published in Scientific Reports. In addition, the study found that farmers who used neonicotinoid seed coatings reduced the number of subsequent applications of other insecticide sprays, leading to potential economic benefits.

Giles Budge and colleagues analysed datasets describing pesticide usage, land use, oilseed rape yield, meteorological conditions and honey bee colony losses over an 11-year period from 2000 to 2010 across England and Wales. The authors found that there was a correlation between increasing imidacloprid usage on oilseed rape and escalating honey bee colony losses. However, colony losses varied across different regions of the country and low spring temperatures were also linked to losses.

The authors also observed that farmers who used oilseed rape seed coatings reduced the number of applications of other insecticides. However, they note that imidacloprid seed coating did not have a consistent positive or negative effect on the yield of oilseed rape over the course of their analysis.

The authors suggest that further studies, including a large scale field-based experiment to determine the impacts on pollinators of neonicotinoid seed coatings on mass flowering crops, are needed.