"Indices for 15 of the 17 species show negative associations with neonicotinoid usage," they said, pointing out that declines have been higher in England than in Scotland, where neonicotinoid usage is comparatively low and butterfly numbers stable.
Overall butterfly numbers declined by 58 per cent on farmed land between 2000 and 2009 despite a doubling in conservation spending in the UK over the period, they point out.
"Further research is needed urgently to show whether there is a causal link between neonicotinoid usage and the decline of widespread butterflies," they conclude.
The results are published in the open-access journal PeerJ.
Have you registered with us yet?
Register now to enjoy more articles and free email bulletinsSign up now