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Epidemiological modelling

Epidemiological modelling of tree pests and diseases

Funded by DEFRA and NERC

Carried out by Matt Combes and supervised by Associate Prof. Stephen Parnell

Invasive forest pathogens are occurring at an increasing rate, resulting in widespread ecological and economic harm in the process. For example, ash dieback disease, caused by the invasive Asian ascomycete fungus Hymenoscyphus fraxineus is causing mortality of ash across the European continent and is estimated to cost billions of pounds in the UK alone. The early detection of invasive pests and pathogens, which can be guided by risk-based surveillance, maximises the likelihood for eradication and reduces the overall costs of management.

I joined the University of Warwick in the New Year as a research fellow in epidemiological modelling of tree pests and diseases after completing my PhD on ash dieback disease with Forest Research and Cardiff University. My research at Warwick has thus far involved working with partners at Forest Research and Observatree to develop a user-friendly tool (DEFRA funded project) that uses Bayesian modelling to provide estimates of the sensitivity and specificity of visual tree health inspections without a ‘gold’ or reference standard. This facilitates the calculation of surveillance metrics such as the confidence of pest/pathogen absence, or the estimated pest/pathogen prevalence.

I have recently started working on the SMARTIES (Surveillance and MAnagament of multiple Risks to Treescapes: Integrating Epidemiology and Stakeholder behaviour) project (NERC funded), which involves different partners (Rothamsted Research, Forest Research, University of York, University of Warwick, Salford University) and will link epidemiological and social dynamic models to explore the potential spread and management of emerald ash borer beetle (Agrilus planipennis) should it arrive in the UK ( The beetle has devastated North American ash species in Canada and the United States, and is now present in Ukraine. The SMARTIES project is therefore vital for protection of ash trees in the UK that are already affected by ash dieback disease. Given my expertise in ash dieback disease, my role in the project will be to model the severity of ash dieback disease in the UK, and then investigate how this may interact with the emerald ash borer beetle.

Lettuce plants in pots infected with fusarium on a shelf in a control environment unit