Habitat use of Philaenus spumarius populations in Mediterranean regions

Understanding the spatio-temporal dynamics of vectors is essential for developing effective management of Xylella fastidiosa , yet the landscape-scale population dynamics of its main European vector, Philaenus spumarius , remain poorly understood. Here, we investigated the spatial and temporal distribution of P. spumarius populations across five heterogeneous agricultural landscapes in Apulia (southern Italy) over two consecutive years. Juvenile and adult populations were monitored at the landscape scale ( n = 168) in woody crops and unmanaged habitats to assess the effects of herbaceous vegetation, soil disturbance, and seasonality on their abundance. In addition, 111 plots were sampled along transects to test the role of habitat refugia (i.e. topographical depressions) on P. spumarius abundance during dry summer periods. In woody crops, nymph abundance was markedly lower in plots with recent soil management and showed positive associations with vegetation structure (height and cover) and vigour. In non-crop habitats, juvenile abundance was positively associated with plant species richness. Adult abundance declined sharply after emergence in most landscapes, with near-complete disappearance during summer followed by recolonization in autumn when herbaceous vegetation cover and vigour increased. Despite comparable initial juvenile populations across landscapes, persistent summer populations were only observed in the landscapes characterized by an extensive presence of unmanaged habitats and in proximity to mesic habitat refugia. Together, our results reveal context-dependent population dynamics shaped by local management and topographical conditions. These findings highlight the limitations of local control measures and the need to consider landscape heterogeneity and seasonal connectivity when designing strategies to limit X. fastidiosa spread.