Prevention and Management
Once they are established, invasive species can be difficult or impossible to remove. Control measures are usually expensive. Preventing invasive species from coming to the province in the first place, or from spreading if they do arrive, is the key to avoiding long-term harm to Ontario’s ecosystems.
To manage invasive species, we must find them early and respond quickly. Finding new invasive species before they spread widely or become established allows us to try to eliminate populations as soon as possible. If it’s not possible to eliminate them, early response could make control measures more effective and reduce their costs. Ontario is working with partners to improve guidelines, tools and processes for early detection and rapid response in the province.
Control
There are three main methods of controlling invasive species -- physical, chemical and biological.
Physical control involves putting up barriers to prevent invasive species from moving into new areas, or physically removing a species from its new habitat. Dredging, dams, traps, electrical fields, mechanical barriers, trenching and sticky bands to catch insects are examples of barriers used to prevent invasive species from entering new areas. Methods of physically removing invasive species from new habitats include mechanical harvesting, hand-pulling plants, and cutting and destroying infested material.
Chemical control involves applying poison to eliminate invasive species. When used properly, these pesticides have little effect on Ontario’s native species and ecosystems.
In Ontario, both physical and chemical controls are used to fight water soldier, an invasive aquatic plant found in the Trent Severn Waterway in 2008. Ontario Ministry of Natural Resources staff pulled plants by hand, and herbicides were applied by a licensed applicator. Efforts to eliminate water soldier are continuing.
Using pesticides in aquatic environments:
A water exterminator’s licence and a water extermination permit are required for anyone seeking to apply a pesticide to lakes, ponds, rivers, streams or wetlands to control an invasive species. The Ontario Ministry of the Environment reviews and approves water extermination permits for the use of pesticides in aquatic environments. The Pesticides Act and Ontario Regulation 914 provide the provincial regulatory framework and outline requirements for training, licensing, permits and pesticide classification. For more information, contact the Regional Pesticide Specialist in your local MOE regional office.
Using pesticides in terrestrial environments:
Ontario’s Cosmetic Pesticide Ban came into effect on April 22, 2009. This ban eliminates the cosmetic use of pesticides on lawns, gardens, school yards and parks. The province allows the use of certain pesticides for projects that help protect biodiversity and natural resources. This includes the use of pesticides to control invasive species. If you want to use a pesticide to control a terrestrial invasive species, please visit the Ontario Ministry of Environment’s website www.ontario.ca/pesticideban. The website will provide you with information on exemptions under Ontario’s Cosmetic Pesticide Ban.
Biological control uses a living organism to reduce or eliminate the population of the invasive species. The organism may eat the invasive species or cause it to become diseased. Control agents are often brought from the original habitat of the invasive species. Proposals for biological control must be carefully assessed to ensure the control species does not become invasive and cause as much damage as the species to be controlled.
Two beetles (Galerucella calmariensis and Galerucella pusilla) are used in Ontario as control agents to manage purple loosestrife, an invasive wetland plant. The beetles reduce the number of purplce loosestrife plants, which helps lessen the damage to native species. Learn more about the Ontario purple loosestrife biological control program.
Integrated Pest Management
Sometimes a combination of control measures, called integrated pest management, is needed to control an invasive species, such as the sea lamprey. The sea lamprey entered Ontario waters through the Welland Canal in the 1920s and spread to all the Great Lakes. It devastated the Great Lakes fishery in the mid-1900s. Canada and the United States joined forces on a comprehensive Sea Lamprey Control Program coordinated by the Great Lakes Fishery Commission.
The program uses a combination of control measures to attack sea lampreys, including:
- Assessment to find streams containing sea lamprey larvae and measure lamprey populations
- Lampricide (a chemical that kills sea lampreys in rivers and streams without significantly harming other species)
- Barriers to block sea lamprey from moving upstream
- Traps to remove sea lamprey from rivers and streams
- Releasing sterile males to reduce the number of lamprey eggs that hatch.
