Parasitoids associated with ambrosia beetles in the Euwallacea fornicatus species complex (Coleoptera: Curculionidae: Scolytinae) in Taiwan

Several species of ambrosia beetles in the genera Euwallacea, Xyleborus, and Xylosandrus (Coleoptera: Curculionidae: Scolytinae) are considered major pests in agriculture, forestry and urban areas. Their concealed lifestyle allows them to evade detection, and increases their chances of being introduced to non-native regions. Their reproduction is dominated by sibling mating within maternal galleries, and this behaviour makes them difficult to control. Although a handful of studies have identified natural enemies associated with ambrosia beetles, very few have done this with the goal of creating a classical biological control programme. In this study, we sought to identify hymenopteran parasitoids associated with the invasive Euwallacea fornicatus species complex. We collected branches from infested trees in a native region in Taiwan, recorded parasitoid emergence, and attempted to rear any emerging parasitoids using laboratory reared hosts and experimentally infested logs. We identified three species of parasitoid wasps that successfully parasitised beetles in the E. fornicatus species complex. These species were all new to science belonging to the genera Eucosmophorus (Braconidae), Phymastichus (Eulophidae), and Plastanoxus (Bethylidae).