Bumblebees are less able to start colonies when exposed to a common neonicotinoid pesticide, which could lead to collapses in wild bee populations, according to new research published today in Nature Ecology & Evolution.
Researchers from Royal Holloway, University of London, and the University of Guelph have found that exposure to thiamethoxam, a common pesticide, reduced the chances of a bumblebee queen starting a new colony by more than a quarter. Building on field studies, the researchers used mathematical models of bumblebee populations which showed that thiamethoxam exposure significantly increases the likelihood that wild bee populations could become extinct.
“Queens exposed to the pesticide were 26% less likely to lay eggs to start a colony,” said Dr 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 bee forages on Royal Holloway's campus (credit, Dr Emily Bailes)
Neonicotinoid pesticides can stop bees forming new colonies
“Building on previous knowledge, we were able to use mathematical models to show that this reduction in colony founding could lead to a very real threat of extinction in wild bumblebee populations,” said Professor Vincent Jansen, also from Royal Holloway. Neonicotinoids are the most widely used class of pesticide in the world. It is vital that we understand the effects of these pesticides on our wildlife.”
The EU has issued a temporary ban on the use of thiamethoxam, as well as two other neonicotinoid pesticides. Neonicotinoids have long been implicated in the decline of bees, butterflies and other species, and there is currently global debate about their usage.
Professor Nigel Raine from the University of Guelph commented: “This research shows that these pesticides can have a devastating effect on bees, and we urgently need to know more about how pesticides could be affecting other species.”
Bumblebee queens already face a hugely challenging task if try to start new colonies. They must first survive the winter, which can cause them to lose up to 80% of their fat reserves, and then surmount the threats posed by, parasites, predators, bad weather, and a lack of resources. The additional impacts of neonicotinoid pesticides could prove devastating.
Professor Mark Brown, also of Royal Holloway, says “Our work is a major step forward in understanding how pesticides may impact bumblebees and other pollinating species.”
This study was funded by a BBSRC-DTG studentship, and the Insect Pollinators Initiative (joint-funded by the Biotechnology and Biological Sciences Research Council, Defra, the Natural Environment Research Council (NERC), the Scottish Government and the Wellcome Trust. It is managed under the auspices of the Living with Environmental Change (LWEC) partnership.)
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