Buzz-worthy science
Expand studies into pesticides’ effect on bees: researcher
There’s been a lot of buzz in recent years about the harm pesticides have had on organisms such as birds and bees.
Many people want these toxic chemicals banned but agricultural researcher Christopher Cutler said the answer lies in fine-tuning our knowledge of their effects.
“To be clear, I’m not pro-pesticide in that I think we should be haphazardly spraying pesticides everywhere,” said Cutler, who is a professor and associate dean of research at Dalhousie University’s Department of Plant, Food, and Environmental Sciences. “You only need to apply them when you need to apply them and we need to do so in a judicious manner.”
As an expert in pollination and insect toxicology, Cutler has focused his attention on the effects of pesticides on bees, specifically the honeybee and bumblebee.
In a study that came out of a workshop in 2017 in Washington, D.C., Cutler looked at the differences in how bumblebees and honeybees are exposed to pesticides.
“The main difference in exposure is their nest — the honeybee is a managed bee in that it lives in a box above the ground, it’s managed by people whereas (wild bumblebees) are ... largely groundnesters,” he explained. “They will nest in old rodent burrows in the ground and that creates a different exposure scenario for the bee.”
Then there’s the boss of the bee world, the queen.
“For a honeybee hive, the queen stays inside of the hive. When honeybees go out and forage for food, it’s always the workers, her daughters,” Cutler said, noting a strong hive contains between 20,000 and 30,000 individuals. “That results in a lot of buffering for the colony” against threats such as pesticide toxicity.
Compare that to a bumblebee colony that would contain 200 individuals at most. And their queen doesn’t sit back on her royal laurels
safe underground.
“(She) is the only bumblebee that survives over the winter and she is the one that goes out and forages for food to start her colony. That means she’s the one that’s producing and she’s out there in the field. She’s much, much more susceptible and if she dies, everything dies. It’s different with the honeybee because if you lose even a few hundred workers, it really might not have any impact on the hive.”
Until now, Health Canada has required any pesticide research such as toxicity tests related to insects be done only on honeybees.
“Now they’re saying maybe we should require them to do tests on organisms like bumblebees as well because they are fairly different in their biology,” Cutler said.
Cutler is optimistic about the health of bee populations in Canada, particularly honeybees. Although there have been major winter die-offs in Ontario and New Brunswick in the past decade, the overall honeybee population has spiked in the last couple of years. The number of beekeepers in Nova Scotia doubled to 461 between 2012 and 2016, according to Statistics Canada.
Cutler’s study was one of three in Canada that came out of the Washington workshop in 2017, which concluded that pesticide regulations need to be strengthened.
“There is evidence that our dependency on insect-pollinated crops is increasing and will continue to do so as the global population rises,” Nigel Raine of the University of Guelph, a co-author of all three papers recently published in the journal Environmental Entomology, said in a news release. “Protecting wild pollinators is more important now than ever before. Honeybees alone simply cannot deliver the crop pollination services we need.”
Cutler said he believes the potential benefits of pesticides outweigh the possible harm, particularly if researchers continue to expand their studies of their specific effects.
“When it comes to things like pesticides, right now there’s a strong push to have products that are very selective. We want things that will kill the target problem, whether it’s a weed or a disease or an insect and be fairly harmless to other things ... I don’t think insecticides are going to go away but I do think they’re going to get better.”