THE ECOLOGY OF ECHINOCOCCUS-MULTILOCULARIS (CESTODA, TAENIIDAE) ON ST-LAWRENCE ISLAND, ALASKA .2. HELMINTH POPULATIONS IN THE DEFINITIVE HOST

The helminths of 1,579 arctic foxes from St. Lawrence Island were investigated by standard methods. The foxes, obtained mainly during the winter from fur trappers, harbored 22 species of helminths. Four of those were trematodes, viz., Maritrema afanassjewi Belopol'skaia, 1952, Orthosplanchnus pygmaeus Iurakhno, 1967, Plagiorchis elegans (Rudolphi, 1802) and Alaria marcianae (LaRue, 1917), each of which occurred in a single host. Two species of cestodes, Diphyllobothrium dendriticum (Nitzsch, 1824) and Mesocestoides kirbyi Chandler, 1940, were uncommon (in 2.7 and 1.3 % of the foxes, respectively). Taenia polyacantha Leuckart, 1856 and Echinococcus multilocularis Leuckart, 1863 were present in about 80 % of the foxes, and Taenia crassiceps (Zeder, 1800) in less than 10 %. The specimens of Taenia spp. from the autumn-winter sample were usually destrobilate. In about 2 % of the foxes, acanthocephalans of six species occurred. Four of those, of the genus Corynosoma Luhe, 1904, were common in marine mammals of the region; a fifth, Corynosoma clavatum Goss, 1940, has been reported previously only from marine birds of the Southern Hemisphere; and the sixth, Polymorphus cf. minutus (Goeze, 1782), has been found widely in waterfowl of the Northern Hemisphere. Of the nematodes, Sobolophyme baturini Petrov, 1930, Cylicospirura felineus (Chandler, 1925), and Physaloptera sp. were rare (with each in only one to three foxes). Trichinella nativa Boev et Britov, 1972 and Crenosoma vulpis (Dujardin, 1844) were uncommon (1.5 and 4 %, respectively). The nematodes most often present were Toxascaris leonina (von Linstow, 1902) (89 %) and Uncinaria stenocephala (Railliet, 1884) (40 %). Several of the rare to uncommon helminths probably were transported to the island by foxes immigrating from the adjacent continents via the pack ice.