A Winnipeg entomologist has concerns about the city's plan to test an alternative to malathion to fog mosquitoes.

The city plans to use a new plant-based insecticide, pyrocide, if it needs to fog for mosquitoes. City officials say pyrocide is biological because its main ingredient comes from chrysanthemums.

But University of Winnipeg entomologist Rob Anderson disagrees.

"That's nonsense. Pyrocide cannot be considered a biological insecticide. It's a chemical or a blend of chemicals like any else," he said.

"The fact it's derived from plants is irrelevant."

In the United States, one ingredient in pyrocide is classified as a possible carcinogen, Anderson said.

The city has been studying alternatives to malathion, which is an insecticide that has been registered for use in Canada since the 1950s.

Health Canada's Pest Management Regulatory Agency has said malathion is toxic to all insects, including those, like honeybees, considered beneficial to humans. It is also considered highly toxic to fish and other aquatic animals.

However, the agency says the insecticide "displays low toxicity" to birds, butterflies and mammals and has determined it is acceptable for use in controlling adult mosquitoes.

Opponents to malathion say the chemical can weaken the immune system and cause cancer, birth defects, intestinal disorders, kidney problems and other health problems. 

Right now the city has no plans to fog because mosquito counts are so low.

That could change within the next week because of rain and warmer temperatures in the weather forecast.

The city says anyone with concerns over mosquito fogging can register to have a buffer zone around their property.