Macroparasite Fauna of Alien Grey Squirrels (Sciurus carolinensis): Composition, Variability and Implications for Native Species

摘要: Introduced hosts populations may benefit of an "enemy release" through impoverishment parasite communities made both few imported species and acquired local ones. Moreover, closely related competing native can be affected by acquiring introduced taxa (spillover) increased transmission risk parasites (spillback). We determined the macroparasite fauna invasive grey squirrels (Sciurus carolinensis) in Italy to detect any diversity loss, introduction novel or acquisition ones, analysed variation burdens identify factors that increase for red (S. vulgaris). Based on 277 sampled from 7 characterised different time scales events, we identified gastro-intestinal helminths 4 arthropods. Parasite richness is lower than squirrel's range independent lags. The most common are Nearctic nematodes Strongyloides robustus (prevalence: 56.6%) Trichostrongylus calcaratus (6.5%), squirrel flea Ceratophyllus sciurorum (26.0%) Holarctic sucking louse Neohaematopinus sciuri (17.7%). All other European cosmopolitan with prevalence below 5%. S. abundance positively host density body mass, C. increases varies seasons. Overall, show enemy release, spillback spillover processes towards occur.