Host selection and potential non-target risk of Dastarcus helophoroides, a larval parasitoid of the Asian longhorned beetle, Anoplophora glabripennis

Abstract

Dastarcus helophoroides Fairmaire (Coleoptera: Bothrideridae), an important parasitoid of the Asian longhorned beetle (ALB) (Anoplophora glabripennis (Coleoptera: Cerambycidae) (Motschulsky)) in Asia, is being evaluated for biocontrol of ALB in the United States. We assessed the responses of D. helophoroides to its native host, ALB, and a non-target surrogate, emerald ash borer (EAB), Agrilus planipennis (Fairmaire) (Coleoptera: Buprestidae), in their respective host plant substrates. Dastarcus helophoroides successfully located, parasitized, and developed on both species. Host-substrate did not affect adult oviposition; however, oviposition did not always result in host parasitism as this is completed by planidial first instar larvae. First instars parasitized significantly more ALB hosts than EAB larvae naturally infesting the cambium tissues of their host sticks, and significantly more progeny was produced from ALB than from EAB. Parasitoid egg to adult development was significantly faster on ALB than on EAB hosts. Adults emerging from EAB were nearly 18% smaller on average than adults emerging from ALB. Prolonged development and smaller body sizes of D. helophoroides emerging from EAB may indicate this species is not likely to be an optimal host and that frass packing behaviors of EAB may reduce its risk of parasitism by D. helophoroides.