Introduction and establishment of biological control agents for control of emerald ash borer (Agrilus planipennis) in Canada

The emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is a serious pest of ash (Fraxinus spp.) (Oleaceae) in North America. Control of emerald ash borer is difficult in natural forest settings; therefore, a classical biological control programme is the most feasible management option for this invasive, nonnative insect. Here, we report the first Canadian release and establishment of parasitoids Tetrastichus planipennisi Yang (Hymeoptera: Eulophinae), Oobius agrili Zhang and Huang (Hymenoptera: Encyrtidae), and Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae) in natural forests in Ontario, Quebec, and New Brunswick, Canada for the control of emerald ash borer. Releases of T. planipennisi were made from 2013 to 2019, O. agrili from 2015 to 2019, and S. galinae from 2017 to 2019. Trees from release sites were destructively sampled to rear out adult emerald ash borers and parasitoids 1–3 years after parasitoid release. Recoveries of T. planipennisi were made at 81% of release sites (13 of 16) 1–2 years after release, and O. agili were recovered from 29% of release sites (4 of 14) 1–3 years after release. Spathius galinae was not recovered. These data provide important information for the development and deployment of a successful biological control programme for the management of emerald ash borer in Canada.