Canadian Forest Service Sault Ste. Marie, Ontario, Canada
Parasitoids have been released in Canada for the biological control of emerald ash borer, Agrilus planipennis, (EAB) since 2013. Release sites were established in Ontario, Quebec, New Brunswick and Nova Scotia and used to determine if parasitoids could successfully establish in Canada and exert regulation on EAB populations. As of 2019 two species, Tetrastichus planipennisi and Oobius agrili, were shown to be established in 81% (13/16) and 29% (4/14) of release sites, respectively. A third species, Spathius galinae has also been released in Canada but establishment has not been demonstrated. Using the network of release sites in Ontario, we did not observe an increase in parasitism rates by T. planipennisi in sites 1-4 years post-release but did observe a slight decrease in parasitism rates by native EAB parasitoids. In 2019 and 2021 we evaluated dispersal of T. planipennisi from a subset of release sites using a network of yellow pan traps deployed during the summer months. From these sites we observed dispersal rates of 2.3-3.2 km per year, consistent with previous laboratory and field observations from the United States. The maximum observed dispersal distance was 48 km from a four-year old release site in Northern Ontario. These results suggest that T. planipennisi has successful established in Canada and has been able to disperse to exploit EAB populations beyond those at the initial release sites.
