Large European field study shows reduced honeybee populations tied to neonicotinoid pesticides

In the UK, researchers from the Centre for Ecology & Hydrology found that exposure to crops treated with neonicotinoid reduced the overwintering success of honeybee colonies – a key measure of year-to-year viability – in two of the three countries.

The results of a large-scale, field-realistic experiment to assess neonicotinoid impacts on honeybees and wild bees across Europe showed colony numbers in Hungary fell by 24 percent in the following spring. In the UK, honeybee colony survival was generally very low, but lowest where bees fed on clothianidin-treated oilseed rape in the previous year.  No harmful effects on overwintering honeybees were found in Germany.

In contrast, the hives in Germany happened to be larger, showed little evidence of disease and had access to a wider range of wild flowers to feed on. This may explain why in this country alone there was no evidence of a negative effect of neonicotinoids on honeybees.