After flood, Ottawa bracing for 'bumper crop' of mosquitoes

Break out the bug spray, Ottawa. After this spring's historic flooding, the city could be plagued with an explosion of mosquitoes.

Kanata North could escape worst of spring infestation thanks to mosquito control program

Experts are warning receding floodwaters could give way to a 'bumper crop' of mosquitoes in and around Ottawa this spring, especially in areas that already have natural wetlands. (Jean Delisle/CBC)

Break out the bug spray, Ottawa. After this spring's historic flooding, the city could be plagued with an explosion of mosquitoes. 

"Mosquitoes need standing pools of water. If you have a very moist spring like this you'll have a good crop," said Jeff Dawson, associate professor of biology at Carleton University.

We're going to have a huge bumper crop of mosquitoes this year.- Mark Ardis, GDG Environnement

"The mosquitoes are going to be pretty bad," agreed Mark Ardis, scientific adviser with GDG Environnement, the company that manages the city's only mosquito control program, in Kanata North.

Some species of mosquito eggs can survive up to 15 years without water, and this spring's flooding could awaken those dormant swarms, Ardis said.

 "We're going to have a huge bumper crop of mosquitoes this year."

Larvicide showing results

Ardis's company runs mosquito control programs in over 40 municipalities across Canada, and is in its second year overseeing the program in Kanata North, an area with lots of natural wetlands.​
GDG Environnement scientific adviser Mark Ardis says there was a 92% reduction in mosquitoes in Kanata North in 2016, thanks to the application of a larvicide in the area. (Jean Delisle/CBC)

The area's councillor, Marianne Wilkinson, said the program has been a success. 

"They did a test just outside the treated area with a 24-hour trap. They got 2,000 mosquitoes in that trap. Then they did it right in the middle of the wetlands. They got 64."

The mosquito control program costs Kanata North homeowners an extra $20 a year on top of their municipal taxes. Wilkinson said some residents aren't happy with the fee, but others are so delighted they'd pay three times the price. 

"The comments I've had from people — 'The first time I've been able to eat outside in 12 years,'  this kind of thing — really makes a difference to the quality of life you have in the community," Wilkinson said.

Food chain not affected

The Kanata North nuisance mosquito control program works by killing the larvae before they develop. A naturally occurring liquid larvicide called BTI is sprayed over pools of standing water, but it only harms the larvae of mosquitoes and blackflies. It is harmless to humans and other wildlife.
Mosquito inspector and biologist Daniel Whitty checks one of the traps within the Kanata North nuisance mosquito control program zone. (Jean Delisle/CBC)

Ardis said the reduction in the mosquito population has no impact on animals further up the food chain, such as birds and bats. 

"Mosquitoes only comprise about three per cent of [those animals'] diet during peak mosquito season, so they're not that important in the food web," Ardis said. 

The University of Ottawa is monitoring the impact of the larvicide on other insects over the course of three years. 

The city of Ottawa is also testing for West Nile virus in the mosquito population. During the 2016 season the city detected a total of 14 West Nile-positive mosquito pools.

There were two cases of humans contracting the virus. 

Permits for the larvicide take six weeks to process, so Ardis said it's now too late for other wards in the city to join the program this spring. 

GDG Environnement is now searching for a similar solution to control the growing tick problem.
Researchers collect larvae outside of the Kanata North nuisance mosquito control program for comparison. (Jean Delisle/CBC)