By Connor Lynch
GUELPH — A study from the University of Guelph has suggested that one of the more widely-used neonicotinoids in Ontario could dramatically increase the risk of extinction of bumblebees.
Former crop scientist and professor at the University of Guelph, Terry Daynard, disagrees.
The study, published last month in scientific journal Nature, tested “field-relevant” levels of exposure to the neonicotinoid thiamethoxam on bumblebee queens. The queens were also subjected to two different stressors; exposure to a parasite, and changes to how long they were allowed to hibernate.
The study measured a 26 per cent reduction in the proportion of queens that laid eggs. “Modelling the impacts of a 26 per cent reduction in colony founding on population dynamics dramatically increased the likelihood of population extinction,” the study said.
Daynard takes issue with that. “All of their modelling is based on one location, and one year (of testing). Using that to make any kind of reasonable prediction on extinction sort of seems like a back of the envelope calculation,” he said.
The paper itself, however, is only part of the problem. The sensationalizing that Daynard has seen, especially by the University of Guelph, is at odds with the actual results from the study, which Daynard said were mixed.
The study measured how many adult offspring the bumblebee queens produced in the season. By the end of it, a higher proportion of the neonic-treated queens had adult offspring than untreated queens. “If you look at what the paper said, there’s not really a strong case for the headlines, that this neonicotinoid is going to make bumblebees extinct,” Daynard said.
Another study, published the same day, also published in Nature, tested the same neonicotinoid’s effect on bees, and received much less media attention. This study tested the effects of thiamethoxam on mature colonies. “We found no impact of insecticide exposure on colony weight gain, or the number of mass or sexuals (breeding bees) produced, although colonies exposed to (smaller amounts of neonics) produced larger males,” the study concluded.
There were no effects to bumblebees but the University of Guelph only dramatized the first study and that captured headlines in the mainstream media, Daynard said, calling the situation “frustrating.”
