Expansion of elevational range in a forest pest: Can parasitoids track their hosts?

Gradients in elevation impose changes environmental conditions, which turn modulate species distribution and abundance as well the interactions they maintain. Along gradient, interacting (e.g., predators, parasitoids) can respond to different ways. This study aims investigate how egg parasitism of a forest pest, pine processionary moth (PPM), Thaumetopoea pityocampa, vary along an elevational gradient (190–2000 m.a.s.l.) mountain range SE Spain, including areas recent expansion, for seven years period (2008–2014). We used generalized linear mixed models ascertain effect both winter North Atlantic Oscillation (NAO) index (a proxy interannual climatic conditions) on rate parasitism, occurrence probabilities two parasitoid species: PPM specialist generalist species. Since four are stratified we repeated all analyses separately lowlands (190–1300 m. a.s.l.) uplands (1350–2000 a.s.l.). Results showed decrease probability main with elevation, although decline was more severe The conspicuous intense than lowlands. Positive NAO values, associated cold dry winters, reduced species—but particularly species—as increases. In context climate warming, it is crucial mitigate latitudinal expansion. Increasing tree diversity at expansion may favor establishment parasitoids, could contribute synchronizing host– minimize risk outbreaks.