Prof. Nigel Raine, the School of Environmental Sciences at the University of Guelph in Canada, has discovered that exposure to thiamethoxam reduces the chances of a bumblebee queen starting a new colony by more than one-quarter.
“Bumblebee queens that were exposed to the neonicotinoid were 26 per cent less likely to lay eggs to start a colony. A reduction this big in the ability of queens to start new colonies significantly increases the chances that wild populations could go extinct.”
The study was conducted with researchers from Royal Holloway University London and examined the impacts of exposing the queen bumblebees to thiamethoxam in spring. This is when the queens emerge from hibernation and prepare to lay their first eggs and establish a colony.
The researchers exposed 300 queen bees to common environmental stressors including parasite infections. About half of the queen bees that successfully emerged from hibernation were then fed pesticide-laced syrup at a level similar to that found in wild pollen and nectar. They then recorded the bees’ egg-laying behaviour and mortality rates. Raine, the Rebanks Family Chair in Pollinator Conservation, explained:
“We observed the queens to see whether low-level pesticide exposure might lead to changes in these important nesting behaviours. When a queen is going to set up a colony, she will secrete wax and form it into containers for nectar and pollen. She will then begin to lay her eggs and sit on them like a bird.”
“This study shows that neonicotinoids could be having a devastating effect on wild bumblebee populations. We urgently need to know more about how pesticides could be affecting other species to make informed decisions about the risks associated with using these chemicals.”