Impact of seawater acidification on longevity and infectivity of trematode cercariae Himasthla elongata: first findings. P. 433-441.
The study was carried out on cercariae of the trematode Himasthla elongata transmitted in the coastal ecosystems of the White Sea. Experiments on the impact of seawater acidification on the life activity of larvae were performed in a specially designed chamber at stable temperature 20°C and light intensity 12 Fc. The lifespan of cercariae was assessed with the use of LT50 index, that is, the time during which half of the cercariae in experimental vessels died. As the water pH decreased from 7.75 (natural pH of water in the White Sea is 7.75—7.8) down to 7.25 and further down to 6.75, a statistically significant decrease of LT50 values was observed. No statistically significant differences between the values of LT50 at water pH 6.75; 6.5 and 6.25 were found. Infectivity of cercariae was assessed with the use of the proportion of successfully encysted larvae in the tissues of the second intermediate hosts, mussels Mytilus edulis. At all the three experimentally tested values of the seawater pH cercarial infectivity was significantly lower than in the control group kept at pH = 7.8, which is natural for the White Sea. Our data indicate that the decrease in the seawater pH, which is forecasted for the Arctic seas by the end of the 21st century, might have an adverse effect on trematode transmission. However, this scenario does not seem likely if we take into account a high acclimation potential of cercariae. The impact of seawater acidity on the activity of free-living larvae of trematodes is extremely poorly studied, and any far-reaching conclusions would be premature. Further studies involving more species and host-parasite associations are the only way to elucidate this problem.
Species identification of Leucochloridium paradoxum (Trematoda) sporocysts. P. 442-448.
During experimental infestation of newborn chickens with metacercariae of Leucochloridium sp., the obtained adults possessed the structure similar to that typical of the species L. paradoxum. Species identification by morphological characters was also confirmed by the results of rDNA genotyping of metacercariae and adults. Our data prove the appropriateness of determination of L. paradoxum sporocysts by their shape and the color of their broodsacks.
Changes in flea (Siphonaptera) vector activity in the Siberian natural plague foci. P. 449-462.
Comparative analysis of vector activity of fleas in the Siberian natural plague foci was carried out during two long-term periods (1967—1980 and 1983—2007, respectively) of experimental studies. The data on block formation frequency in imago infested by Yersinia pestis were analyzed in 127 experiments with the use of 15 flea species and subspecies. It was shown that an increase of vector activity of the carriers occurred in all the Siberian plague foci (Altai, Tuva, and Transbaikalia) during rather small time period (30—40 years). The confidence level of the distinctions in frequency of the insect «blocking» between the analyzed periods was high in all the three foci (P < 0.001).
Distribution and specificity of host-parasite relations of fleas (Siphonaptera) in the Central Caucasus. P. 463-475.
In the territory of the Central Caucasus, constituting a one-fifth of the Greater Caucasus, the order of fleas is represented by 87 species, 67 of which are associated with mammals, and 20 species, with birds. Six endemics of the Greater Caucasus are present in the region, and 3 of these species are endemics of its central part. Fleas of 72 species are distributed along the entire longitudinal extent of the Central Caucasus. Fleas of 18 species are associated with highlands, 2 species are found only in steppe foothills and forest-steppe midlands. The distribution is associated with the presence of suitable hosts or depends on other reasons. In this region, rodents of the family Cricetidae are main hosts of more than one third of all the flea species. Passeriform birds of the families Hirundinidae, Motacillidae, and Muscicapidae are main hosts for the most part of bird flea species. The Central Caucasus is characterized by a high degree of commonality of species composition with the Western and Eastern Caucasus. This is explained, first of all, by the widespread distribution of many flea host species throughout the Greater Caucasus.
The fauna of bloodsucking mosquitoes (Diptera: Culicidae) of the Pechora-Ilych nature reserve (Komi Republic). P. 476-484.
New data on the fauna and ecology of mosquitoes (Diptera: Culicidae) of the Pechora-Ilych Nature Reserve of the Komi Republic (collections performed in 2016—2017 in the territory of the Yakshinsky site) (4604 specimens) and material from the collection of the science museum of the Komi Institute of Biology (collecting performed in 1964, 2195 specimens) are represented in the paper. New species for the reserve include Aedes behningi Martini, 1926, A. mercurator Dyar, 1920, Culiseta bergrothi (Edwards, 1921), and Culex torrentium Martini, 1925. The list of mosquito species of the Pechora-Ilych Reserve comprises 27 species.
Detection of spectrum of pathogens in ixodid ticks from combined natural foci of the Baikal Region. P. 485-501.
Ixodid ticks, collected in different areas of the Baikal Region in 2013—2017, were tested for the spectrum of transmissive pathogens. According to the increase in the frequency of occurrence, genetic markers of the following pathogens were revealed: tick-borne encephalitis virus (TBE), the monocytic erlichiosis (HME), human granulocytic anaplasmosis (HGA), ixodid tick-borne borreliosis (ITB), and rickettsioses. Considerable differences have been detected in spatial and temporal prevalence of the agents. Infected Ixodes persulcatus were much more common than Haemaphysalis concinna in our region. Besides, 15% of taiga ticks have been co-infected with two or more agents in different combinations.
Short Review of the main trends in parasitology in Russia based of the analysis of International Scientific Conference (VI Congress of the Russian Society of Parasitologists) (15—19 October, 2018. St. Petersburg). P. 502-512.
The main trends in parasitology are reviewed on the basis of analysis of the scientific conference held in frames of the 6th Congress of the Russian Society of Parasitologists. Oral presentations (136) were grouped into 12 problematic sections according to the main areas of parasitological science; the conceptual and general review lections were placed into plenary sessions; a part of papers (26) were presented as posters. Main trends and perspectives of development were defined for every fundamental branch of parasitology; the novelties comparing to the international level of similar research were analyzed. It was detected a progress among medical-veterinary and plant pathological papers in methods and technology basis aimed to prompt survey and diagnostics of parasite-caused diseases and the development of safety measures for environment and society.
Contents of Journal «Parazitologiya», Year 2018, Volume 52, Issues 1—6. P. 513-518.
Summary is absent.