Factors affecting pine processionary moth (Thaumetopoea pityocampa) incidence in Mediterranean pine stands: A multiscale approach

The occurrence of the pine processionary moth (Thaumetopoea pityocampa, hereafter PPM) in Mediterranean forests and plantations is increasing concern as processes such global warming forest cover expansion have amplified frequency virulence outbreaks. This study attempts to provide complete an overview possible different factors involved susceptibility PPM 98 stands Central Spain. A large area (∼3,000 km2) was considered, including three spatial scales (<1 ha, 1 10 ha) four tree species (Pinus pinaster, P. nigra, sylvestris, pinea), monitored over a 4-year period. Models were fitted for each scales, well combination them (multiscale model). Pine had strong influence on vulnerability PPM, with higher incidences dominated by pinaster nigra lower those sylvestris pinea. Grazing pressure, factor thus far disregarded, also determining, prominent role at both multiscale stand-scale levels. Other variables highly influential some showing greater resistance or diversity sizes, density, larger non-host species. Open habitats played incidence: we detected that, locality plot scale, presence clearings occupied bushes rocky outcrops reduced while more simplified structure produced opposite effect. We conclude that incidence structurally simple forests, grazing pressure abundant open spaces without woody vegetation may favour pupation. To reduce damage should be managed avoid oversimplified structures. Patches promoted, shrubs areas. implies avoiding overgrazing other management models leading excessive increase bare soil. Nevertheless, it noted implementation these recommendations consider remaining challenges need addressed current context change, increased risk wildfires emergence pests diseases.