Macroparasites of Pallas's squirrels (Callosciurus erythraeus) introduced into Europe

Abstract Introduced pets released in natura can lead to sanitary risks for native fauna and humans. We analysed the macroparasite fauna of a total of 49 Pallas's squirrels, Callosciurus erythraeus , from two populations introduced into urbanised areas in Europe ( n  = 16 ♀ and 13 ♂ from Antibes, France, 43°33′N–7°7′E; n  = 11 ♀ and 9 ♂ in from Dadizele, Belgium, 50°52′N–3°5′E). Of the 185 identified ectoparasites from Antibes, 183 were sucking lice Enderleinellus kumadai , with male squirrels 10 times more intensely infested than females. The flea Nosopsyllus fasciatus was found on two hosts. No hard ticks were recovered. Of the 131 arthropods specimens from Dadizele, 45 belonged to E. kumadai , with male squirrels three times more intensely infested than females. Eighty-six arthropods belonged to another sucking louse, Hoplopleura erismata , with males infested twice as intensely as females. No fleas or hard ticks were found. We only found 12 immature Hymenolepis sp. cestodes in the small intestine of three squirrels from Antibes and two immature Mastophorus sp. female nematodes in the stomach of a squirrel from Dadizele. We found no other helminths in the body cavity, heart, lung, liver, kidney or bladder. The macroparasite fauna of these two squirrel populations is consistent with what is expected from an introduced host, i.e., a few species dominated by specialist taxa imported with founders. The scarcity of other rodent species in the urbanised areas where Pallas's squirrels were sampled may explain the low variety of newly acquired macroparasites. The discrepancy in sucking lice infestations between males and females could be due to differences in either behaviour or physiology in this non-sexually dimorphic host. Based on the macroparasites found in this study, we expect minimal sanitary risks for both native fauna and humans in urbanised habitats such as those in our study.