Surveillance of ash trees under multiple threats: Integrating emerald ash borer and ash dieback dynamics with stakeholder behaviour - Correction

1. Across the world, emerging pests and diseases are increasing in number, rangeand co-occurring with other invasive biotic factors. Ash trees (Fraxinus excelsior L.;Oleaceae) in Great Britain face the potential invasion of the emerald ash borer (EAB;Agrilus planipennis Fairmaire; Coleoptera: Buprestidae) and the ongoing impact ofash dieback (ADB; Hymenoscyphus fraxineus T. Kowalski (Helotiales: Helotiaceae)).Surveillance and management strategies accounting for land manager behaviour arecrucial for improved control.2. We developed a spatially explicit model that integrates (i) the estimated prevalenceof ADB, (ii) the dynamics of EAB arrival and spread and (iii) a socio-dynamics model,based on a values-driven theory that simulates land manager decision-making in re-lation to surveillance and tree management. In the model, if EAB is detected, contin-gency measures—including tree felling and intensified monitoring—are enacted, withthe potential to eradicate or slow its spread. We used the model to assess whethertargeting high-risk sites with traps, using routine tree inspections by land managers,or encouraging volunteer surveillance (with or without subsidised trapping) couldsignificantly slow EAB spread.3. Interviews (n = 45), a survey (n = 368), and three workshops (n = 27) informed thesocio-dynamics model's structure and parameterisation. The interaction betweenEAB and ADB is complex, with potential positive effects (e.g. increased perceivedvalue of ash) and negative effects (e.g. belief that ash cannot be saved, misidentifica-tion of decline causes).4. Results showed that if land managers are made aware of EAB, health and safetyinspections have a substantial role to play in slowing the spread but are unlikely to lead to eradication due to the pest's cryptic larval phase. Official trapping at a limitednumber of locations is similarly unlikely to succeed in early detection and eradica-tion unless entry pathways are well-defined, and ash connectivity is low. Volunteertrapping is important for early detection and if this is subsidised, EAB eradicationbecomes more likely.5. Synthesis and applications. Tree-health policies must balance identifying likely entrypoints and deployment of traps, targeted information campaigns and surveillancesubsidies for land managers. Our unique, cross-disciplinary approach can be appliedto other pest/pathogen systems to inform tree-health plans and how to balanceresources.