CERCARIAL FAUNA OF TREMATODES OF MOLLUSCS (GASTROPODA, PULMONATA) IN RESERVOIRS OF NORTH-WESTERN AND CENTRAL UZBEKISTAN

Some features of the fauna of cercariae of trematodes of mollusks in reservoirs of Northwestern and Central Uzbekistan produced by gastropods Lymnaeidae Rafinesque, 1815, Planorbidae Rafinesque, 1815, Physidae Fitziger, 1833 and Thiaridae Gill, 1871 have been studied. In the reservoirs of the Amu Darya (within Uzbekistan) and Zarafshan rivers, natural infection with fluke larvae was observed in 14 species of mollusks, Lymnaea (8 species), Planorbis (1 species), Gyraulus (1 species), Anisus (2 species), Physa (1 species) and Melanoides (1 species). In total, 24 species of cercariae belonging to trematodes of 11 families Fassiolidae, Echinostomidae, Philophthalmidae, Paramphistomidae, Gastrothylacidae, Notocotylidae, Plagiorchidae, Sanguinicolidae, Strigeidae, Diplostomidae, Schistosomatidae and Bilharziellidae were found.The cercariae identified by us, according to the nature of the search and infection (second intermediate and definitive) hosts, are divided into the following three groups: the first group cercariae encyst in the environment, their final hosts are infected by ingestion of adolescariae settled in aquatic substrates. The second group cercariae penetrate into the body (of the second intermediate hosts) of insects, fish, amphibians, etc. and turn into metacercaria. The final hosts are infected by eating the second intermediate hosts. The third is the cercariae released from the host mollusk, they attack and actively penetrate the blood vessels of the final host through its integument.