Seeking the unseen: A review of host-finding strategies of parasitoids attacking wood-boring forest pests

Authors: OTEN, KELLY - North Carolina State University; Duan, Jian; JOHNSON, COURTNEY - North Carolina State University

Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2026
Publication Date: 4/15/2026
Citation: Oten, K.L., Duan, J.J., Johnson, C.L. 2026. Seeking the unseen: A review of host-finding strategies of parasitoids attacking wood-boring forest pests. Annals of the Entomological Society of America. https://doi.org/10.1093/aesa/saag010.
DOI: https://doi.org/10.1093/aesa/saag010

Interpretive Summary: Invasive wood boring insects such as the emerald ash borer (EAB) and the Asian longhorned beetle (ALB) are the most destructive forest tree pests in the U.S., where they have caused extensive mortality of urban and forest trees, fundamentally altering forest composition and imposing substantial economic costs (>$1billion annually) for tree removal, replacement, and management. The success of biological control of these insects depends on the efficient attacks on suitable pest stages (hosts) by the introduced agents or parasitoids, which involves multiple processes and various cues associated with hosts’ habitat, host-associated microbial organisms, and/or hosts themselves. Here, we review the major steps in host finding by parasitoids of wood-boring hosts and synthesize current knowledge on the chemical, vibrational, visual, and other cues that mediate each stage of the process. We highlight how these cues operate across different spatial scales, interact with parasitoid morphology and behavior, and shape the success of biological control programs targeting economically important wood-boring pests. Finally, we identify key knowledges gaps and point to some future research directions aimed at improving the selection, deployment, and monitoring of biological control agents (parasitoids) in forest ecosystems. This information benefits forest managers, biological control practitioners, and regulatory agencies by improving strategies to protect trees, reduce economic losses, and enhance sustainable pest management.

Technical Abstract: The success of biological control hinges on efficient host foraging by the agents or parasitoids, which involves multiple processes and various cues associated with hosts’ habitat, host-associated symbionts and other microbial organisms, and/or hosts themselves. In general, parasitoid interactions with concealed hosts such as wood-boring hosts differ significantly from those with exposed hosts (e.g., surface-feeding caterpillars, aphids) as they must rely on a more complex of hierarchy cues to first locate hosts’ microhabitats and then hosts for their production. These differences influence the parasitoid's host-finding strategies, specificity, and their efficacy in suppressing their host populations. Here, we review the major steps in host finding by parasitoids of wood-boring hosts and synthesize current knowledge on the chemical, vibrational, visual, and other cues that mediate each stage of the process. We highlight how these cues operate across different spatial scales, interact with parasitoid morphology and behavior, and shape the success of biological control programs targeting economically important wood-boring pests. Finally, we identify key knowledges gaps and point to some future research directions aimed at improving the selection, deployment, and monitoring of parasitoid biological control agents in forest ecosystems.