Pesticides that were scrutinized for harming bees may be contributing to the decline of the butterfly population, a new study shows. Scientists blame neonicotinoids or anti-sap-feeding insect pesticides for the declining population of not only bees, but also butterflies, small tortoiseshells and small skippers.
In the first scientific study to examine the effect of pesticides on British butterflies, the researchers found that 15 of 17 species which commonly thrive in the countryside and farmlands have population decline linked to increased use of insecticides specifically neonicotinoids.
Neonicotinoids or neonics, neuro-active insecticides chemically similar to nicotine, is widely used around the world for almost two decades. It works by coating onto the seeds that farmers plant. However, in the last decade, bee populations declined and scientists linked the use of neonics to the condition now dubbed as honey-bee colony collapse disorder (CCD).
Researchers from University of Stirling and University of Sussex, in collaboration with Butterfly Conservation and the Centre for Ecology and Hydrology, gathered data from at least 1,000 sites based from population data from 1985 to 2012 to examine if butterflies are affected too.
They found that the decline in butterfly population occurred mostly in England. However, in Scotland, where the use of neonics was low, the number of butterflies remained stable.
"Our study not only identifies a worrying link between the use of neonicotinoids and declines in butterflies, but also suggests that the strength of their impact on many species could be huge," Dr. Andre Gilburn , an ecologist from the University of Stirling, said.
The findings show that the Essex skipper and small skipper declined by 67 percent and 62 percent from 2000 to 2009, respectively. The small tortoiseshell declined by 64 percent and the wall brown butterfly population had a 37 percent decline.
"Further research is needed urgently to show whether there is a causal link between neonicotinoid usage and the decline of widespread butterflies or whether it simply represents a proxy for other environmental factors associated with intensive agriculture," the authors wrote in their study published in the journal PeerJ.
"We are extremely concerned with the findings of the study and are calling for urgent research to see whether the correlations we found are caused by neonicotinoid use, or some other aspect of intensive farming," Dr. Tom Brereton, head of monitoring at Butterfly Conservation, said.
