Ectoparasites of the Pallas squirrel, Callosciurus erythraeus, introduced to Japan


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    When the Pallas squirrel was originally introduced to Japan from Taiwan it was called the Formosan squirrel, but that subspecies Callosciurus erythraeus thaiwanensis (Bonhote, 1901)is now regarded as synonymous with the more widespread C. e. flavimanus Geoffroy, 1831 (Corbet & Hill, 1992), also called belly banded or red-bellied squirrel.

2 Professor Sadao Nogami, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa 252-8510, Japan.


Abstract. The squirrel Callosciurus erythraeus (Pallas) (Rodentia: Sciuridae) was intentionally introduced to Japan in 1935 and has become established throughout much of the country. Although they live mainly in forests, Pallas squirrels come into gardens and are frequently fed by people or kept as pets, so their ectoparasites could be of potential medical as well as veterinary importance. During 2001–2003 we conducted the first ectoparasite survey of Pallas squirrels in Japan. From 105 C. erythraeus captured in Kamakura District of Kanagawa Prefecture on Honshu Island, three types of ectoparasite were found: 52 specimens of the sucking louse Neohaematopinus callosciuri Johnson (Anoplura: Haematopinidae), 26 fleas Ceratophyllus (Monopsyllus) anisus Rothschild (Siphonaptera: Ceratophyllidae) and four nymphs of the tick Haemaphysalis flava Neumann (Acari: Ixodidae) on 22, 13 and one squirrels, respectively. Evidently in Japan C. erythraeus carries relatively few ectoparasite species; this may be a contributory factor to their invasive success. Further investigations are needed to assess risks of zoonotic transmission of plague or murine typhus by C. anisus, of louse-borne typhus by N. callosciuri and of tularaemia and especially Japanese spotted fever (Rickettsia japonica) by H. flava.