Neonicotinoid insecticides linked to wild bee decline
The CEH research used data provided by former government research arm FERA. It examined 62 wild bee species, as well as oilseed rape cropping patterns across England between 1994 and 2011 - the time period spanning the introduction of wide-scale commercial use of neonicotinoids.
Three active ingredients from the neonicotinoid family of systemic insecticides are currently subject to strict ‘partial bans’ introduced by the European Commission in 2013 in light of mounting evidence of the insecticides’ impacts on bees and other non-target insects.
The CEH study’s findings suggest that neonicotinoid use is linked to large-scale, long-term declines in bee populations.
Declines were three times more severe amongst species - like the buff-tailed bumblebee - that regularly feed on oilseed rape crops, compared to those that forage from a wider variety of plants. The researchers said this implicates the crop is a key means of exposure to neonics among wild bees.
They said losses in bee biodiversity correlated with neonicotinoid use, but that the pesticides alone are not likely to be behind massive bee declines seen across the northern hemisphere.
Lead author Ben Woodcock explained, "As a flowering crop, oilseed rape is beneficial for pollinating insects. This benefit however, appears to be more than nullified by the effect of neonicotinoid seed treatment on a range of wild bee species.
"Although we find evidence to show that neonicotinoid use is a contributory factor leading to wild bee species population decline, it is unlikely that they are acting in isolation of other environmental pressures.
"Wild bees have undergone global declines that have been linked to habitat loss and fragmentation, pathogens, climate change and other insecticides.” ■