LIFE-CYCLE OF BOTHRIOCEPHALUS CLAVICEPS, A SPECIFIC PARASITE OF EELS

The life-cycle of the tapeworm Bothriocephalus claviceps (Goeze, 1782) (Cestoda: Pseudophyllidea), a specific parasite of eels (Anguilla spp .), was studied under experimental conditions. It was demonstrated tha t the parasite completed its development within 4 months at the temper ature range of 22-24 degrees C. Embryonic development was finished in 2 days at this temperature, when coracidia spontaneously hatched. The rate of their development was controlled by water temperature, with de layed formation of coracidia at lower temperatures (8 days at 10-12 de grees C). At 2-4 and 6 degrees C, development did not take place but t he eggs remained viable; at 33 degrees C the eggs died. The procercoid s developed in copepods of the species Macrocyclops albidus, M. fuscus , Megacyclops viridis, Cyclops strenuus, C. vicinus and Acanthocyclops vernalis (Copepoda: Cyclopidae); their development was finished after 8-12 days at 22-24 degrees C. The definitive hosts, eels, acquired in fection after ingestion of infected copepods; the prepatent period of the parasite was more than three months. Perch (Perca fluviatilis) and guppies (Poecilia reticulata) were shown to serve as paratenic hosts of the parasite; in guppies, the tapeworms survived up to 14 days afte r exposure and they developed similarly to tapeworms in the definitive host.