Phragmites Biocontrol in Ontario - Progress So Far

Biocontrol provides gradual, long-term suppression which facilitates habitat restoration. 

Agriculture and Agrifood Canada and The University of Toronto have lead the research and development for biological control of invasive Phragmites in Canada.

Development of biocontrol for invasive Phragmites began over 20 years ago with the search for a candidate biological control agent in Europe, the home range of invasive Phragmites. Two stem boring moths – Archanara neurica and Lenisa geminipuncta – were selected and extensive host-range testing demonstrated that both moth species are safe and specific to invasive Phragmites and safe for native species.

Ducks Unlimited Canada is partnering with these organizations in building capacity for a largescale release program.

Establishing Biocontrol in Ontario

Following Federal authorization, releases of the Phragmites biocontrol agents in Canada began in Ontario, in 2019. Insects are released into new field locations in the spring as both eggs and larvae (caterpillars). Eggs are placed into plastic cups with mesh bottoms that protect the eggs from predators but allow hatching larvae to crawl out and find invasive Phragmites stems to feed on. Eggs can also be hatched in the lab and the emerging larvae are placed into cut sections of Phragmites stems. Blocks of these stems are then placed into the field, after which the larvae will chew their way out and switch to new Phragmites stems growing around them.

From 2019 to 2024, approximately 30,000 A. neurica and L. geminipuncta have been released as biocontrol agents against invasive Phragmites. These releases span a growing network of 50 sites across southern Ontario. The release sites reach from Essex County in the southwest, up to North Bay, and east of Ottawa.

Photo: Cut phragmites stems inoculated with larvae of biocontrol agents in preparation for release. Photo Credit: Michael McTavish.

Monitoring for Biocontrol Feeding

Monitoring efforts, led by scientists from University of Toronto and Agriculture and Agri-Food Canada, have consistently detected feeding damage by the insects a few months after release, indicating that release methods are effective for introducing the insects into the field.

After releasing biocontrol agents, all release sites are monitored in summer when feeding damage is most visible to track how the agents are doing. Stems damaged by biocontrol will have one or two boreholes (where the larvae enter and exit the stems) and dead or wilted tissue above where they were feeding. In subsequent years, there has been consistent or increasing levels of feeding damage observed from the offspring of the insects that were released. This damage indicates that the biocontrol agents can reproduce, overwinter, and disperse locally within release sites. These encouraging monitoring results suggest that the biocontrol agents are on their way to creating self-sufficient populations.

Photo: Larval bore hole in invasive phragmites stem. Photo Credit: Claire Schon.

Biocontrol Next Steps

Since biocontrol releases of A. neurica and L. geminipuncta began in 2019, a core set of operational protocols have been developed by AAFC and U of T detailing how to rear, release, and monitor the agents. With these protocols in place, the project is now shifting its focus to scaling up releases across southern Ontario.

Spread of biocontrol agents happens naturally at a local scale as the moths disperse to nearby invasive Phragmites populations. The large-scale release strategy is built around the use of “nurse sites”. These are field locations with robust, self-sustaining populations of the agents, where insects can be collected and moved to accelerate spread and target specific new locations. To achieve large-scale, landscape-level management of invasive Phragmites, a network of nurse sites is being created across southern Ontario.

In addition to the nurse site program, Ducks Unlimited Canada supports continuing research by scientists at the University of Toronto. Research is focused on refining release and monitoring methods for the biological control agents, including the use of drones to track agent feeding and spread.

Photo: Summer Phragmites damage monitoring. Photo Credit: Michael McTavish.

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