Epidemic Characteristics Of Diplostomum And Identification On Two Kinds Of Diplostomidae Of Esox Lucius In Irtysh River

By adopting the conventional methods of fish parasites investigation, modern molecular biology techniques, and population ecology and bio-statistical methods on some pathogen species of Diplostomum which were investigated on Esox lucius in Irtysh River in China territory, we research phylogeny and epidemiology characteristics, the conclusions were as follows:(1)By 8 times for field sampling on Esox lucius in Irtysh River in China territory, we collected 263 fishes. Epidemiological investigation and statistical analysis of Diplostomum which parasited in eyes, the result showed that: the total infection rate of Diplostomum is 34.98%, gradual increase trend with the increase in body length; the lowest infection rate is 4.17%, appears in the fish body length longer than 50cm; infection intensity of Diplostomum is increase with the increase in body length, and the average infection intensity is 10.74; S2/X>1 indicated that the parasitic of Diplostomum show a aggregated distribution, and the aggregation extent is increase with the increase in body length.(2)By molecular biology methods, identify the Diplostomum species which parasites in Esox lucius eye lens. Comparative analysis 18S-ITS1-5.8S rDNA sequence of species to be identified and the same sequence of Diplostomum in GenBank database, we found that the homology between the identified species and Denmark reported before( KJ888995) is 99.6%, it show they are the same species, Diplostomumparacaudum. This species is first discovered in China, is a new record for the Chinese species. We analysis and discuss of molecular phylogeny and genetic relationship of Diplostomum paracaudum in different place.(3)We collected a fluke metacercariae in Esox lucius eye vitreum, make a preliminary morphologic- al identification and further molecular biological identification, comparative analysis ITS1-5.8S-ITS2 rDNA sequence of species to be identified and the same sequence of Diplostomum in GenBank database. The result showed that the homology between the identified species and Germany reported before(JQ665459)is 99.82%, metacercariae shape is basically the same whit morphological features described by Nordmann(1832), only individual measure slightly different. It is tylodelphys clavata, belongs to tylodelphys, Diplostomidae, Platyhelminthes. This species is first discovered in China, is a Chinese new record species, and tylodelphys is a Chinese new record species genus.