Winnipeg waits on Health Canada approval of new odourless mosquito insecticide

Winnipeg has yet to learn if it will have an odourless mosquito insecticide ready to fight the hoards of mosquitos getting ready to hatch and descend upon the city in upcoming months, as its newly designated fogging agent is still awaiting Health Canada approval.

The new compound is called DeltaGuard 20EW, an insecticide containing deltamethrin, a synthetic version of a natural insecticide produced by chrysanthemum flowers. The need for a new fogging agent arose as malathion, the city’s go-to insecticide for decades, is no longer available for sale in Canada and Winnipeg’s stockpile of the chemical has been declared by Health Canada to be too old for use.

In 2015, the World Health Organization declared malathion as “probably carcinogenic to humans,” prompting the search for its replacement in Winnipeg, the only Canadian municipality to use malathion to fog for mosquitos. The city uses a combination of larviciding and residual treatment programs throughout the warmer months but relies upon fogging when mosquito trap numbers reach a peak.

Last year, insecticide fogging began on June 16 and the previous year on June 10, yet Ken Nawolsky, Insect Control Manager with the City of Winnipeg, says he is confident that regulatory approval for DeltaGuard will be completed before this year’s mosquitos hit their full stride.

“We’ve done the last 15 years (of fogging) and the average is June 30,” said Nawolsky, to Metro News. “We normally don’t get any hatch of the summer (mosquito) species until around the 20th of May, so we’re feeling very comfortable in terms of when the first adult mosquito control program would occur and when the product would be here.”

DeltaGuard is reported to be more environmentally friendly than malathion and is effective in smaller quantities. Plus, it’s odourless. “When people see us fogging they won’t smell anything,” Nawolsky said. “They’re wondering if we’re spraying with water—no, it’s just that it has no odour, that’s one of the characteristics of this product.”

The long-held practice of mosquito fogging in Winnipeg is matched with an almost as lengthy tradition of criticism, with its detractors arguing that fogging has little effect in comparison to the lion’s share of the mosquito eliminating work done by larviciding and that it comes with negative health consequences. Back in 2005 a group of physicians under the heading of the Canadian Association of Physicians for the Environment called on Winnipeg to put a stop to fogging with malathion, citing the toxicity of the chemical and arguing that other approaches to controlling mosquito populations, which can carry West Nile virus, should be used.

Writing for the CBC, Bartley Kives argues that mosquito fogging is more of public relations stunt than health-based practice and that residents would “freak out” if the city stopped fogging. “Simply put, nuisance-mosquito fogging does very little to control mosquito populations,” says Kives. “While the weather is the main factor that determines whether large numbers of blood-sucking insects can emerge in Winnipeg, the real reason they largely are not present every day from Easter to Thanksgiving is the city engages in aggressive larviciding.”