Khrebtova I.S., Aksenova O.V., Kondakov A.V

Trematodes of the genus Diplostomum have a complex life cycle which includes the change of two intermediate hosts. At the first stage of development the egg of the trematode turns into a miracidium which infects a freshwater gastropods from the Lymnaeidae family and passes into the sporocyst or parthenite stage. Thus, the metamorphosis of miracidium into cercariae occurs in the mollusk which after maturation leaves the first intermediate host and subsequently infects the second intermediate host, the fish. Infected fish become easy prey for waterfowl which act as the final host for trematodes. The aim of our study was to assess the infestation of lymnaeid snails from Arctic lakes with trematodes of the genus Diplostomum. For this total DNA was isolated from the pond snails fixed in 96% alcohol and the internal transcribed spacer 2 (ITS2) was amplified that made it possible to detect the presence of trematodes in mollusks. To identify trematodes the obtained nucleotide sequences were compared with data from NCBI GenBank. During the study, the presence of two species of trematodes Diplostomum baeri and D. spathaceum in the Arctic waters was confirmed. As a result, of two unique sequences of the ITS2 spacer of Diplostomum baeri were identified on the Kola and Chukotka Peninsula different from the widespread haplotype from Germany and Canada by three substitutions. This is the first finding of this trematode species confirmed by a molecular method, which indicates its distribution in the Arctic. Also, our results showed that the D. spathaceum distributed in the lakes of Siberia, Central Asia, and Europe.

Acknowledgements: This study was supported by Russian Science Foundation (project no. 21-74-10155).