Questions and Answers: Wasps as biological control agents for Emerald Ash Borers

This page is part of the Guidance Document Repository (GDR).

Looking for related documents?
Search for related documents in the Guidance Document Repository

The Canadian Food Inspection Agency (CFIA) has approved two species of wasps from China as the first biological control agents for use in Canada in an attempt to control the spread of the emerald ash borer (EAB), which has been destroying Canada's ash trees. EAB is not native to Canada and has few natural enemies here.

The two species of wasps are Tetrastichus planipennisi (T. planipennisi), a member of the Eulophidae wasp family, and Spathius agrili (S. agrili), a member of the Braconidae wasp family. The approval of these wasps is part of a long term strategy designed to reduce the population of EAB and reduce the destruction of Canada's ash trees. Only T. planipennisi are being released in Canada at this time. The release of the wasps will be closely monitored through ongoing scientific studies.

What do the wasps look like and do they sting?

T. planipennisi and Spathius agrili are very small species of wasps approximately 4.0 mm in length. They do not sting humans.

How do the wasps target EAB?

T. planipennisi deposit their eggs within the larvae of host insects, while Spathius agrili deposit their eggs on the surface of their host larvae.

T. planipennisi very specifically targets EAB, while Spathius agrili may occasionally attack the insect larvae of species similar to EAB.

Only T. planipennisi are being released in Canada at this time. When the eggs hatch, the young wasps feed on the host larvae, killing them. The wasps will not eliminate populations of EAB entirely, but it is hoped that they will reduce the population to a point where EAB is manageable in the Canadian environment.

How will the wasps be introduced to Canadian forests?

The T. planipennisi wasps are being released in southwestern Ontario by Natural Resources Canada – Canadian Forest Service. They were introduced in blocks of ash wood which contained wasp pre-pupae already inside them. The blocks were suspended from trunks of EAB-infested ash trees at experimental sites on June 4, 2013. The wasps will emerge from the larvae and fly off in search of other EAB to target.

Two more releases will take place after the first release, and then three more releases will take place later in the summer, all at the same sites. The experimental site is located in Huron County in southwestern Ontario.

Although two species of wasps were approved for release, evaluation of release data in the United States has later indicated that Spathius agrili is not effective north of the 40°N latitude, and therefore would not be effective in Canada.

Will these wasps attack other pests?

T. planipennisi is very species-specific. It is expected to attack only EAB larvae, and not native species. Risks to native species were considered prior to release based on both CFIA review of potential risks, and on standards developed by the North American Plant Protection Organization.

What does "biological control" mean?

The classical "biological control" strategy is the introduction of a prey species into a region to regulate a pest species through the development of a balanced host-prey relationship which prevents the pest developing to numbers that cause significant damage. The biological agents that have been approved by the CFIA to regulate EAB are T. planipennisi and Spathius agrili. Both species of wasps are native to northern China. It is believed that EAB came from the same region in China before it was introduced into Canada. Both species of wasps are natural predators of EAB in their places of origin.

How are biological control agents approved?

If a Canadian resident wishes to import biological control agents to Canada, they must first submit a petition to the CFIA, following specific guidelines.

The petition is reviewed by a Biological Control Review Committee. This committee may include taxonomists, ecologists, scientists, and specialists from federal and provincial governments and Canadian universities.

The petition is also reviewed by representatives from the United States Department of Agriculture and from Mexico's Plant Health Department. All comments are taken into consideration before the committee makes a recommendation to the CFIA to approve or deny the request.

Once the petition is reviewed, the committee provides their recommendation to the CFIA. The Chief Plant Health Officer for the CFIA makes the final decision.

A letter is sent to the applicant advising them of the decision.

Who made the application in this case?

Natural Resources Canada made the application, which the CFIA approved.

Additional Information

Date modified: