Bees face potential impacts after mosquito fogging
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This article was published 10/07/2021 (568 days ago), so information in it may no longer be current.
It appears the City of Brandon’s mosquito fogging program conducted earlier this month was successful in eliminating the pests.
Anecdotally, there doesn’t appear to be as many pesky mosquitoes tormenting neighbourhoods.
But, neither are the other bugs, according to Bee City Brandon chairperson and biologist Sherry Punak-Murphy.
“I have had a couple people write to me to tell me they have not seen as many insects in the yard since spraying, including mosquitos, bees and other insects,” she said.
Bee City Brandon is a chapter of the national Bee City Canada, and Brandon is the only city in Manitoba to embrace the ideals of the national body.
“As advocates, there are the three pillars for Bee City: Education, habitat growth and celebrating Pollinator week in June,” Punak-Murphy said.
Bee City Brandon is a group of volunteers concerned by a decline of pollinators
The latest insecticide to tackle the city’s mosquito problem, DeltaGard 20EW, was used earlier this month for the second time since it replaced the previous chemical, malathion, which the World Health Organization declared a potential carcinogen in 2015.
The active ingredient in DeltaGard, deltamethrin, does not damage human genes, affect human reproduction and has a low rate of absorption into skin. According to Health Canada, it is likely not a carcinogen.
DeltaGard has been tested a lot on honeybees, Punak-Murphy said, “but wild bees are different from honey bees. With the wild bees, most aren’t out at the same time as the spraying occurs.”
DeltaGard is a contact insecticide, she said. Droplets have to drop onto the insect for it to actually work. The majority of bees, or any insect not out at night, don’t face death as readily as mosquitoes, which are night-dwelling creatures.
“They’re out at night and their bodies are smaller than a bumblebee. A bumblebee would need more chemicals in order to kill it.”
Punak-Murphy was researching the effects of the DeltaGard insecticide on the bee population and preparing the information for Bee City Brandon’s social media accounts and the people inquiring about the lack of bees in their yards.
“They have tested it on bees. It is deadly to bee species, but most of our bees are solitary. They’re in the ground. They’re not getting the chemical when it’s getting sprayed.”
At least 80 per cent of the wild bee population is next in the ground and there are more than 300 species of bees in the province.
DeltaGard doesn’t have a huge impact on the bee population in Brandon from what Punak-Murphy has gathered from the literature.
At the same time, she added, “any insecticide is not good for insects or humans.”
Bee City Brandon is not advocating for the end of mosquito spraying.
“You’ve got public health reasons for spraying,” Punak-Murphy said. “When you’re dealing with conservation issues, you have to weigh the pros and the cons, and sometimes as humans, we do stuff that impacts wildlife, unfortunately.”
The major threats to pollinators is habitat loss, climate change, lack of pollinator pathways and chemicals.
DeltaGard 20EW does have a bee hazard label on the Pest Management Regulatory Agency website, Victoria Wojcik noted.
“The labels aren’t particularly informative beyond stating that there is a hazard,” the director of science and research for Pollinator Partnership at Bee City Canada added.
“Based on the research, our recommendation is restricted to us, meaning only where essential. Given that there are lethal impacts, the use recommendation is to apply in the evening when there are no bees actively on flowers, to avoid application on flowers, and to aim at cooler nights.”
With fogging, there are a few issues with the recommendations, she said.
“You can’t be discriminatory to avoid flowers, there is a lot of drift. Application should be on a cool night with low wind. … In terms of extended residual toxicity, there is data that it can be two days for bumblebees. There will be a risk to bumblebees after application, and what are the mitigation impacts?”
Wojcik suggested the only way to assess the residual toxic impact on the bee population is to do a body count.
“If anything, this would provide more information on impacts, etc. It could also be a baseline. We don’t really have this sort of proactive data. Much of the non-target impact data is incidental.”
The chairperson of the Manitoba Beekeepers’ Association, Ian Stepplar, said beekeepers in the province work together with farmers spraying their fields with pesticides.
“We ask them to spray in the evenings when the bees are in their hives. Spraying at night isn’t as potent and the bees avoid the sprayed field for the most part.”
By morning, the pesticide has usually burned off. Plus, he added, bees tend to avoid the area because they can smell the pesticide.
Fogging for mosquitoes is a totally different strategy, he noted. It permeates the area and lingers in bush lines, killing natural pollinators.
“I see this discussion with this insecticide as part of an educational program,” Punak-Murphy said.
“We’re just concerned citizens about the decline of pollinators. … So our big thing is education. That’s our biggest mandate. Then creating pollinator habitat and educating people on what kind of plants they can grow in their yards and what they can do to protect pollinators.”
To learn more about Bee City Brandon, visit their Facebook account at beecitybrandon, their Twitter at @beecitybrandon and Instagram at @beecitybrandon.