Physiologically-based eco-epidemiological model of Xylella fastidiosa infection in olive groves

Xylella fastidiosa (Xf) is a plant pathogen of global concern, responsible for severe diseases in numerous crops, including Olive Quick Decline Syndrome (OQDS) in Europe. Understanding the eco-epidemiological processes governing the Xf infection and disease progression is essential for supporting the development of effective and sustainable management strategies against Xf outbreaks. We developed a novel physiologically based eco-epidemiological model to simulate Xf dynamics in olive agroecosystems. The model integrates vector population dynamics, vector–host interactions, transmission processes, disease progression in olive trees, explicitly accounting for the influence of temperature, water availability, and host plant composition. It is formulated as a system of ordinary and delay differential equations solved numerically, whose compartments represent vector life stages, herbaceous vegetation, non-host plants, reservoir plants, and successive olive tree disease stages defined by infection status and canopy desiccation severity. The model was calibrated and validated using field observations from 16 olive groves affected by Xf in Apulia (Italy), comparing simulated and observed distributions of olive trees across disease severity classes over time. Simulations successfully reproduced key epidemiological features, including the dynamics of disease severity classes, the duration of the asymptomatic period, the time from symptom onset to complete canopy desiccation, and the seasonal peaks in infected vector populations. This model advances our understanding of Xf epidemiology and provides a potential mechanistic tool to support pest risk assessment and integrated pest management by enabling scenario testing of disease spread and control strategies in olive-growing landscapes under different environmental conditions.