title: Macroparasite fauna of alien grey squirrels (Sciurus carolinensis): composition, variability and implications for native species.
abstract: Introduced hosts populations may benefit of an "enemy release" through impoverishment of parasite communities made of both few imported species and few acquired local ones. Moreover, closely related competing native hosts can be affected by acquiring introduced taxa (spillover) and by increased transmission risk of native parasites (spillback). We determined the macroparasite fauna of invasive grey squirrels (Sciurus carolinensis) in Italy to detect any diversity loss, introduction of novel parasites or acquisition of local ones, and analysed variation in parasite burdens to identify factors that may increase transmission risk for native red squirrels (S. vulgaris). Based on 277 grey squirrels sampled from 7 populations characterised by different time scales in introduction events, we identified 7 gastro-intestinal helminths and 4 parasite arthropods. Parasite richness is lower than in grey squirrel's native range and independent from introduction time lags. The most common parasites are Nearctic nematodes Strongyloides robustus (prevalence: 56.6%) and Trichostrongylus calcaratus (6.5%), red squirrel flea Ceratophyllus sciurorum (26.0%) and Holarctic sucking louse Neohaematopinus sciuri (17.7%). All other parasites are European or cosmopolitan species with prevalence below 5%. S. robustus abundance is positively affected by host density and body mass, C. sciurorum abundance increases with host density and varies with seasons. Overall, we show that grey squirrels in Italy may benefit of an enemy release, and both spillback and spillover processes towards native red squirrels may occur.
authors: Department of Biosciences, Università degli Studi di Milano, Milan, Italy.
authors: Claudia
authors: C
authors: Romeo
authors: Department of Theoretical and Applied Sciences, Università degli Studi dell'Insubria, Varese, Italy.
authors: Lucas A
authors: LA
authors: Wauters
authors: Department of Veterinary Sciences and Public Health, Università degli Studi di Milano, Milan, Italy.
authors: Nicola
authors: N
authors: Ferrari
authors: Department of Veterinary Sciences and Public Health, Università degli Studi di Milano, Milan, Italy.
authors: Paolo
authors: P
authors: Lanfranchi
authors: Department of Theoretical and Applied Sciences, Università degli Studi dell'Insubria, Varese, Italy.
authors: Adriano
authors: A
authors: Martinoli
authors: Department of Ecology and Biodiversity Management, Muséum National d'Histoire Naturelle, Paris, France.
authors: Benoît
authors: B
authors: Pisanu
authors: Department of Theoretical and Applied Sciences, Università degli Studi dell'Insubria, Varese, Italy.
authors: Damiano G
authors: DG
authors: Preatoni
authors: Department of Biosciences, Università degli Studi di Milano, Milan, Italy.
authors: Nicola
authors: N
authors: Saino
mesh_terms: D000818:Animals; D006376:Helminths; D058865:Introduced Species; D007558:Italy; D008003:Phthiraptera; D012589:Sciuridae / Q000469:parasitology*; D005423:Siphonaptera