Progress in the classical biological control ofAgrilus planipennisFairmaire (Coleoptera: Buprestidae) in North America

Abstract

AbstractFirst detected in North America in 2002, the emerald ash borer (EAB) (Agrilus planipennisFairmaire; Coleoptera: Buprestidae), an invasive phloem-feeding beetle from Asia, has killed tens of millions of ash (FraxinusLinnaeus; Oleaceae) trees. Although few parasitoids attack EAB in North America, three parasitoid species were found attacking EAB in China: the egg parasitoidOobius agriliZhang and Huang (Hymenoptera: Encyrtidae) and two larval parasitoidsTetrastichus planipennisiYang (Hymenoptera: Eulophidae) andSpathius agriliYang (Hymenoptera: Braconidae). In 2007, classical biological control of EAB began in the United States of America after release of these three species was approved. In 2013, release of the larval parasitoids was approved in Canada. Research continues at study sites in Michigan, United States of America where the establishment, prevalence, and spread ofO. agriliandT. planipennisihave been monitored since 2008. However, establishment ofS. agriliremains unconfirmed in northern areas, and its release is now restricted to regions below the 40th parallel. In 2015, approval for release ofSpathius galinaeBelokobylskij (Hymenoptera: Braconidae), an EAB larval parasitoid from the Russian Far East, may be granted in the United States of America. Researchers are guardedly optimistic that a complex of introduced and native natural enemies will regulate EAB densities below a tolerance threshold for survival of ash species or genotypes in forested ecosystems.