Bumblebees are less able to start colonies when exposed to a common neonicotinoid pesticide – which could lead to collapses in wild bee populations, scientists have warned.
Exposure to thiamethoxam – the active ingredient in Cruiser seed treatment – can reduce the chances of a bumblebee queen starting a new colony by more than a quarter, they found.
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Mathematical models used by researchers showed thiamethoxam exposure significantly increases the likelihood that wild bee populations could become extinct.
The study was undertaken by researchers from Royal Holloway University, the University of London, and the University of Guelph.
Their findings have been published in the journal Nature Ecology & Evolution.
“Queens exposed to the pesticide were 26% less likely to lay eggs to start a colony,” said Gemma Baron, from the School of Biological Sciences at Royal Holloway.
“Creating new bee colonies is vital for the survival of bumblebees – if queens don’t produce eggs or start new colonies it is possible that bumblebees could die out completely.”
A temporary ban on the use of thiamethoxam, as well as two other neonicotinoid pesticides, remains in place after it was imposed by the EU in 2013.
The research is the latest study to suggest that neonicotinoids are dangerous to pollinators – although the assertion is disputed by industry leaders and agrochemical manufacturers.
Scientists who undertook the latest study said it was vital that the effects of neonicotinoid pesticides on wildlife were understood before allowing their continued use.
But the environmental campaign group Friends of the Earth went further, saying the government should permanently ban neonicotinoid pesticides.
FoE campaigner Sandra Bell said: “This new study comes hot on the heels of the largest field trials of neonicotinoids showing harm to honey bees and wild bees.
“It also follows new evidence of how these pesticides leak into the environment and turn up in wildflowers posing further risk to bees.
“It is clear that use of these chemicals on any crop poses a risk to bees and other wildlife.”
The study was funded by the Biotechnology and Biological Sciences Research Council, Defra, the Natural Environment Research Council, the Scottish government and the Wellcome Trust.