In a groundbreaking study published in CABI Agriculture and Bioscience, researchers have revealed the potential role of an accidentally introduced parasitoid from East Asia in combating the devastating impact of the invasive box tree moth (Cydalima perspectalis) across Europe and North America. This discovery could mark a significant turning point in the preservation of wild box trees (Buxus spp.), which are currently facing severe threats due to extensive defoliation caused by this invasive pest.
The box tree moth, native to eastern Asia, has become a formidable ecological adversary since its accidental introduction to Europe and North America. Feeding voraciously on boxwood plants, the larvae cause extensive damage threatening the survival of native wild Buxus populations. Current control strategies are limited and often ineffective, prompting scientists to explore biological control agents that can selectively target this pest without harming native ecosystems.
Central to the new findings is an unidentified species of Eriborus (Hymenoptera: Ichneumonidae), a parasitoid wasp discovered to parasitize C. perspectalis larvae. The initial detection of this parasitoid in a botanical garden in Basel, Switzerland, in spring 2024, triggered a cascade of surveys aimed at assessing its establishment and influence on box tree moth populations. Researchers conducted extensive fieldwork across multiple sites in Northwestern Switzerland and Southwestern Germany, where wild box tree habitats coexist with ornamental plantings.
Molecular analyses combined with morphological characterization confirmed that the specimens collected in Switzerland and Germany are conspecific with Eriborus wasps known from South Korea, the native range of the box tree moth. Interestingly, parasitism rates recorded during the study were impressive, with rates as high as 68% in wild box tree stands in Germany and 32% in Switzerland. These results indicate that the parasitoid is well established and actively suppressing moth populations in natural environments.
The inadvertent arrival of Eriborus sp. appears to represent a remarkable case of adventive biological control — a natural enemy establishing in a non-native region without deliberate human introduction. Such cases challenge traditional paradigms of biological pest management and underscore the complex dynamics of invasive species and their natural enemies. It is notable that similar events have been recorded in recent years, including the introduction of Trissolcus japonicus targeting the brown marmorated stink bug (Halyomorpha halys) and Leptopilina japonica parasitizing the spotted wing drosophila (Drosophila suzukii).
The success of this accidental biological control hinges partly on the reproductive biology of Eriborus sp., which exhibits lytokous parthenogenesis, allowing a single parasitized larva or cocoon transported with ornamental box trees to initiate viable populations. This reproductive strategy accelerates establishment potential, facilitating rapid spread across invaded habitats where their host, the box tree moth, proliferates.
Despite promising parasitism levels, researchers caution that thorough ecological evaluations must precede any formal consideration of Eriborus sp. as a classical biological control agent. Specificity tests are underway to rule out potential adverse effects on native moth species and other non-target Lepidoptera. Preliminary quarantine trials show promise, but real-world observation in Swiss and German forests will be critical to understanding the actual host range and ecological interactions.
Dr. Marc Kenis, Head of Risk Analysis and Invasion Ecology at CABI, emphasized the urgent need for innovative pest management solutions due to the scarcity of effective control options. The unintentional distribution of Eriborus sp. presents a unique opportunity to protect not only European wild Buxus species but also ornamental and potentially native boxwood populations in North America, including Mexico and the Caribbean, where the pest is expanding its range.
The study highlights broader implications for invasive species management, illustrating how unintentional introductions of natural enemies can contribute to ecosystem resilience. Such occurrences blur the lines between classical and adventive biological control, suggesting a need to reconsider regulatory frameworks and risk assessments that often inhibit the deployment of introduced natural enemies.
Moving forward, multidisciplinary collaboration will be crucial for monitoring the spread and impact of Eriborus sp. across different geographies and ecological contexts. Combining field surveys, molecular tools, and experimental host range testing will enable scientists to harness the benefits of this parasitoid while mitigating ecological risks.
This research also sets a precedent for proactive surveillance of parasitoids and other natural enemies inadvertently arriving alongside invasive pests. Early detection and characterization can expedite biological control responses, improving conservation outcomes for threatened plant species while reducing reliance on chemical pesticides.
As fields of invasion ecology and biological control continue to evolve, integrative approaches leveraging accidental introductions like Eriborus sp. may provide an invaluable, cost-effective tool to restore balance in invaded ecosystems. This case exemplifies how nature’s own regulatory mechanisms, if carefully understood and managed, can assist humanity in battling pervasive invasive pests.
In conclusion, the accidental introduction of Eriborus sp. holds significant promise for controlling the box tree moth, one of the most destructive invasive pests threatening European and North American boxwood species. Continued research and cautious implementation of this adventive biological control agent could ultimately save wild box tree populations from ecological extinction while reshaping pest management paradigms worldwide.
Subject of Research: Not applicable
Article Title: Will an accidentally introduced parasitoid save European box trees?
News Publication Date: 6-Nov-2025
Web References: DOI: 10.1079/ab.2025.0081
References:
Marc Kenis, Seraina Klopfstein, Minho Lee, Seunghwan Lee, M. Lukas Seehausen, ‘Will an accidentally introduced parasitoid save European box trees?,’ CABI Agriculture and Bioscience, 6 November 2025, DOI: 10.1079/ab.2025.0081
Image Credits: Tim Haye/CABI
Keywords: Biocontrol, invasive species, box tree moth, Cydalima perspectalis, parasitoid, Eriborus sp., adventive biological control, invasive pest management
Tags: accidental introduction of parasitoidsbiological control of invasive pestsbox tree moth control strategiesCABI Agriculture and Bioscience studyCydalima perspectalis impactEastern Asia parasitoids in Europeecological restoration of box treesecological threats to boxwood plantsEriborus parasitoid waspinvasive species managementnative Buxus conservation effortspreserving biodiversity in forestry
