The Greater Moncton Pest Control Commission (GMPCC) follows an Integrated Pest Management (IPM) model in its efforts to control mosquitoes. Knowing that mosquitoes play an important role in the local ecology, the Commission seeks to reduce the adult mosquito population by specifically controlling mosquito larvae.
It is estimated that a successful larvicidal program could reduce the adult population by 70%. The remaining 30% are available for the local ecology as a food source and to serve as pollinators.
The GMPCC’s mosquito control program consists of 3 phases that cycle throughout the control season:
- The monitoring of mosquito larvae densities throughout the Greater Moncton area
- Application of biological pesticides
- Follow-up post count
There are over 190 sites that are monitored on a continuing basis throughout the Greater Moncton area. Some of these sites are only active during the spring or after heavy rains. The marshes along the Petitcodiac River are the most significant contributors to the mosquito population and therefore are monitored at least once per week.
The monitoring staff will enter a site with a long handled 250ml dipper and a quiet step. A representative sampling is taken in order to establish a larvae concentration for the site. Typically, spring conditions can produce up to 250 larvae per dip while late summer conditions may only produce 5-10 larvae per dip at the high end of a breeding cycle.
Monitors note the field conditions on data sheets so that priorities may be set for pesticide application. Generally, an application will be performed if the larvae concentration exceeds 10 Larvae/250ml.
Since the early 80’s, the Commission has used a biological pesticide called Bacillus thuringiensis Israelensis (Bti).
Bti is a naturally occurring bacterium found in soil. It is only effective during the larval growth stage and remains effective between one to two days. Depending on the organic content, acidity and temperature of the water it is dispersed in, Bti can provide control of mosquitoes for between on and four weeks. Bti is available in corncob bases that contain spores and delta-endotoxin crystals of Bacillus thuringiensis, Serotype H-14 (B.T. H-14). GMPCC usses the corncob base.
Application of larvicide is either done by hand or by using a mechanical broadcast spreader on an all terrain vehicle. Hand application is achieved by forming a line of applicators who carry a supply of larvicide in a pouch. The applicators walk in tandem and broadcast the granules at the desired rate. The topography of the site in conjunction with the dispersion of the water will determine which method will provide the most efficiency.
See the Equipment page for detailed illustrations of application and safety equipment used by the Commission’s staff.
Quality control is of paramount importance to an effective larvae control program. Each site is visited 24 hours after an application is made. This ensures that abatement efforts are successful by monitoring kill rates as well as finding any pools of water that were missed during the application.
If after 48 hours larvae are still present, the application staff will be called in again to reapply. Vectobac is very effective and less than a 100% kill rate is unusual.