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In this paper, literature on the fauna of the family Tabanidae (Diptera) of Yakutia is analyzed. The fauna of the region is represented by 37 species. Distribution of horseflies in 7 natural areas of Yakutia is also analyzed.

The work is devoted to the study of the dynamics of reproduction and phenotypic changes in a population ofthe tick-borne encephalitis virus (TBEV) during long-term infection, feeding of ixodid ticks, and under different temperature conditions. It was shown that the increased temperature significantly affected the level of TBEV reproduction in ixodid ticks. During ticks feeding, however, more rapid and intensive TBEV reproduction was observed in comparison with infected ticks kept at the increased (32—37°C) and room temperatures. TBEV strains of the European and Siberian subtypes successfully replicated and formed long-term infection in ticks that were both primary (Ixodes ricinus, I. persulcatus) and secondary (Dermacentor reticulatus) virus vectors. The strain of the Siberian subtype reached its maximum titres in D. reticulatus, and the strain of the European subtype, in I. ricinus and D. reticulatus ticks. The long-term reproduction of the TBEV of the European and Siberian subtypes in ticks, both primary and secondary vectors, increased the heterogeneity of viral population, however, virus variants retained high neuroinvasiveness characteristic to the virus adapted to mouse CNS cells. The TBEV strains of different subtypes differed in the phenotypic heterogeneity of the population under different conditions. In contrast to the Absettarov (European subtype) strain, the heterogeneity of the virus population of EK-328 (Siberian subtype) strain on the phenotype of plaques on PEK cell culture was significantly influenced by feeding of D. reticulatus ticks after long-term reproduction of the virus in them.

Laboratory and industrial cultures of crickets are frequently being damaged by viral infections, and the major causes include iridescent viruses, widely occurring pathogens of arthropods and vertebrates. An increase of the mass death of crickets in culture was observed recently in Russia. The disease symptoms corresponded to those of iridescent virus infection. Amplification with primers specific to a gene fragment of major capsid protein of Insect iridescent virus type 6 (IIV-6) resulted in product of expected size for DNA samples of diseased crickets. Amplicon sequencing showed sequence similarity of 100 and 97 % to homologous region of IIV-6 genome from Gryllus bimaculatus (Genbank accession # AF247641) and from Chilo suppressalis (# AF303741), respectively. Positive PCR signal (with 100 % sequence similarity of amplicons) was obtained for DNA samples from tissues of crickets of three species (G. bimaculatus, Gryllus locorojo, Acheta domestica), including larvae and adults without disease symptoms and eggs, as well as the adult cockroach Blattella germanica. The obtained results indicate the possibility of diverse ways of disease transmission in laboratory and industrial cultures of insects.

The activity of digestive enzymes (proteinases and glycosidases) in the intestinal mucosa of the zope (Ballerus ballerus L.) was determined. As a result of cestode infection with Proteocephalus torulosus Batsch, 1786, proteinase activity in the zope intestinal mucosa decreased, glycosidase activity increased, and sucrase activity remained unchanged. A decrease in proteolytic activity was due mainly to the decline of proportions of serine proteinases and metalloproteinases. The extract of P. torulosus inhibited the proteolytic activity of the host intestinal mucosa and commercial trypsin samples in vitro.

The probabilistic approach was applied for species identification of Culex pipiens pipiens / torrentium mosquito females collected in the Sablino caves (Leningrad Region). The distances between landmarks of the radial wing veins r₍₂₊₃₎ and r₃ were measured and the frequency distribution of the r₍₂₊₃₎ / r₃ wing vein index was analyzed. The obtained distribution characterized by two maxima coinciding with distribution maxima obtained earlier by other authors for German populations of Culex pipiens pipiens and C. torrentium. In the sample from Sablino caves, the most specimens grouped at the maximum of the Culex pipiens normal distribution. We propose to use the Bayes factor (BF) to select those mosquito females which most likely belong to C. p. pipiens. In the sample studied, the Bayes factor was more than 10 for 72.5% of the specimens, which is strong or very strong evidence in favor of C. p. pipiens. For 16.5% of individuals BF was more than 0.1 or less than 10 (moderately positive and weak evidence in favor of one of the two species). Overall, 11% of the females obtained BF less than 0.1, which is strong or very strong evidence in favor of C. torrentium. Selecting the specimens belonging to C. p. pipiens, preference should be given to individuals with the highest BF values, for more reliable species identification.

In Primorsky Territory and Sakhalin Region, 10 flea species were collected in 2012—2017 from 6 species of carnivores. The most complicated collections of species of the genera Ctenocephalides and Chaetopsylla were performed in winter and early spring (December—January, April), for fleas of the genus Paraceras, in spring and autumn (April—May, October). The fauna of fleas parasitizing on carnivores of Primorsky Territory includes a single endemic species of the Eastern Asiatic subregion Chaetopsylla (Ch.) mikado and 2 species, Ch. (Ch.) appropinquans and Ch. (Ch.) zibellina distributed in southeastern Siberian province of European-Siberian subregion and in Eastern Asiatic subregion.

Janetta Vyacheslavovna Korneva, PhD, Dr. Sc., an active researcher in the fine structure and tissue organization of parasitic flatworms, passed away on September 12, 2017, at the age of 55. All the work of Dr. Korneva J. V. is connected with the Papanin Institute of Biology of Inland Waters of the Russian Academy of Sciences (IBIW RAS, Borok, Yaroslavl Region).