Edmonton's Mosquito Control Program

Mosquito control relies heavily on understanding the biology of the species involved, knowledge of its habitats, and constant monitoring of the control area. Our most successful method for reducing pest populations is to attack the immature stages of the pest's life cycle when they are most vulnerable.

In other provinces where disease carrying mosquitoes are a problem, adult control is justified but is relatively inefficient. In the Edmonton area, where mosquitoes are primarily nuisance only, adult control is minimal.

Since 1974 the City's mosquito control program, developed by the University of Alberta, has targeted larval stages of nuisance Aedes spencerii species. In general, our larval control programs drastically reduce the production of Aedes mosquitoes within the City's 1,400 square kilometre mosquito control boundaries.

Comprehensive monitoring programs throughout this zone identify treatment needs which vary with the impact of snowmelt and summer rainstorms. The amount of rainfall can result in anything from no action at all to a full blown aerial and ground-based larviciding operation.

Treatment Methods

For speed and efficiency, over 90% of treatment is contracted to helicopter services that use dry, granular larvicide formulations. Off-road sites that are inaccessible to helicopters and ditch habitats along road allowances are treated by the City's ground-based wet spray delivery equipment. Applications are restricted by:

• Mosquito development beyond the fourth larval instar since these are no longer susceptible to the treatments available.
• Windy or rainy conditions.
• Approximately 5% of the outer area accessible by helicopter is not treatable because of owner refusal, noise sensitive farming operations, beehives or other environmental concerns.

These restrictions can result in advanced stages of mosquito development prior to the completion of a campaign. In addition to these normal types of restrictions, high water levels in the spring can also result in greater problems as moving water cannot be treated. Larvicides are applied only to temporary or semi-permanent bodies of water containing larvae.

Permanent bodies of water are not treated because they contribute very little towards nuisance mosquito production. Additionally, these habitats support more complex insect communities including mosquito predators like dragonflies.

Treatment campaigns are terminated with the development of pupal stages of the mosquito which can appear in as little as a week to ten days after hatching. Information about spraying activities and adult mosquito populations is publicized through media releases and interviews.

Treatment Effectiveness

Over a typical spring and summer season, our control methods achieve over 90% reduction of nuisance Aedes which develop in the breeding sites we are able to treat. Proper treatment of Aedes breeding sites with the conventional insecticide Dursban® reliably causes 100% larval mortality under all known habitat conditions.

Post-treatment surveys also show Dursban® effectively terminates larval mosquito development in 80-100% of treated sites checked. Summertime performance of more selective larvicides like Bti show similar results, however, they are much less effective in cooler spring conditions. Large-scale use of Bti has also been limited due to poor cost efficiency and the reduced effectiveness of aerial applications.

Key dates in Edmonton's battle against mosquitoes:

• 1953 - Aerial mosquito control initiated.
• 1972 - Spraying DDT for mosquitoes was discontinued.
• 1973 - Mosquito control monitoring laboratory started.
• 1975 - Edmonton's district operated mosquito program was centralized under a single pest control unit.
• 1980 - Introduction of bacterial control product (Bti) for usage in sensitive areas.
• 1991 - Initiated mosquito development site reduction (landfill) program.
• 1993 - Discontinued mosquito adulticide program (fogging) targeting the city's river valley and ravine system.
• 1993 - Provincial funding assistance eliminated (approximately 50% of budget); eventually all surrounding municipalities discontinued mosquito control in the capital region.
• 1994 - Implemented a cost-saving efficiency with a one-person ditch crew versus two-person.
• 2003 - West Nile virus found in Alberta. The province initiated a three-year funding program for mosquito vector detection and source reduction.

Did you know?

Edmonton's program was one of the first to implement global positioning technology to assist helicopter pilots in identifying "no fly" areas such as noise-sensitive farming operations.

For more information:

Pest Management

12304 107 ST
Edmonton AB  T5G 2S7

Telephone	In Edmonton: 311 Outside Edmonton: 780-442-5311
Fax	780-496-4978
Email	treebugs@edmonton.ca