Main content area

On the life cycle of Hymenolepis evaginata Barker and Andrews, 1915 (Cestoda: Cyclophyllidea), a parasite of muskrats, Ondatra zibethica (L., 1766)

Greaves, T. A., Jarecka, L., Burt, M. D. B.
Canadian journal of zoology 1989 v.67 no.2 pp. 502-504
Hymenolepis, Ondatra zibethicus, intermediate hosts, invertebrates, mammals, oncospheres, parasites, small intestine, water birds, New Brunswick
Between October 2, 1985, and November 16, 1986, 129 muskrats, Ondatra zibethica were collected in New Brunswick and examined for parasites. Forty-one of the muskrats harboured the the cestode Hymenolepis evaginata in the small intestine, with infections ranging from 1-10 worms per host. To determine the intermediate host of H. evaginata, a number of aquatic and terrestrial invertebrates were exposed to oncospheres in the laboratory. Full development of a tailed cysticercoid only occurred in the ostracod Cyclocypris laevis. The cysticercoid undergoes typical protocepyhalic development in this micro-crustacean. This characteristic, regarded as primitive, occurs in hymenolepidids found in aquatic birds. It appears that although this cestode is commonly found in mammals, it is more closely related to aquatic avian hymenolepidids than to those found in terrestrial mammals.