Gastrointestinal Parasitic Helminth Fauna of the Pallas's Squirrel (Callosciurus erythraeus) from the Uto Peninsula, Kumamoto, Kyushu, Japan and Analyses of the Abundance of an Alien Nematode, Strongyloides callosciureus

Abstract

The gastrointestinal parasitic helminth fauna of 55 alien Pallas's squirrels (Callosciurus erythraeus) from the Uto Peninsula, Kumamoto, Japan, exterminated as part of an eradication program in October, 2010, were surveyed for the present study. Only four nematode species were detected, including one dominant strongylid, Strongyloides callosciureus (prevalence: 49.1%; abundance: 2.13 ± 0.66), and three other fragmental species, Brevistriata callosciuri, Capillariidae gen. sp. and Rictularia cristata (prevalence: 0.18%–0.55%; intensity: 1–3). The ratio of the mean to variance and the k-value of the negative binomial distribution pattern on the abundance of S. callosciureus were 0.089 and 0.283 (0.387 and 0.278 in male and female hosts), respectively. Relationships between the abundance of the strongylid and relevant factors such as individual host traits (sex, age, and body size) were examined using a generalized linear model. Male hosts harbored significantly more worms than the females in the optimal model. These sexual differences are attributable to the behavioral features of the host.