Rickettsia spp. are ubiquitous in nature and capable of causing diseases of varying severity. The most extensive group comprises the spotted fever group (SFG) Rickettsiae, the members of which are predominantly transmitted by ticks. The expansion of tick habitats observed in recent decades poses an increasing threat of dissemination of tick-borne infections into regions previously considered non-endemic. The aim of this study was to determine the prevalence of SFG Rickettsiae in ixodid ticks collected in Northwest Russia and to characterize the species diversity of these pathogens within the study area. Questing adult ixodid ticks (n = 4566) were collected from eight regions of Northwest Russia (Arkhangelsk, Kaliningrad, Leningrad, Novgorod, Pskov and Vologda Regions, as well as the Republic of Karelia and St. Petersburg) in 2023 to 2025 (from April to September). The species composition included Ixodes ricinus (n = 1683), Ixodes persulcatus (n = 2404), and Dermacentor reticulatus (n = 479). Genomic DNA was extracted from individual ticks and screened for SFG Rickettsiae using real-time PCR, followed by conventional PCR targeting the gltA, ompA, ompB, and sca4 (gene D) genes. Nucleotide sequences obtained for a subset of positive samples for the various genes were analyzed. The overall prevalence of SFG Rickettsiae was 12.6% (95% CI: 11.7-13.6). Circulation of the following species was detected: Rickettsia helvetica, Rickettsia conorii subsp. raoultii, Candidatus Rickettsia tarasevichiae, Rickettsia monacensis, and Rickettsia felis. The findings indicate considerable species diversity of SFG Rickettsiae in natural foci of Northwest Russia. Rickettsia monacensis was detected in ixodid ticks within the study area for the first time, and R. felis was identified in Russia for the first time.

Mosquitoes of the genus Anopheles were collected in the Republic of Karelia, St. Petersburg, Leningrad Region, Novgorod Region and Pskov Region (Russia) in order to clarify their distribution and genetic and morphological diversity. ITS2 sequence analysis of An. maculipennis s. l. (58 specimens) showed that they belonged to An. beklemishevi, An. messeae, An. daciae and An. maculipennis s. str. Taking into account our earlier data on An. claviger, this means that there are five Anopheles spp. in north-western Russia whose records are confirmed by molecular methods. We revealed An. daciae in Leningrad and Pskov Regions for the first time and confirmed its distribution in Karelia. Anopheles beklemishevi was found near the Arctic Circle in north-western Karelia. The study of morphology of the female heads of An. daciae, An. messeae and An. beklemishevi showed they may potentially be used for differentiation of these species.

This paper explores the specific features of the fauna of fleas (Siphonaptera) of Karelia, as part of a larger geographic region comprising Northwestern Russia and Fennoscandia. Our analysis included information from the available summary reviews and data from the PARHOST1 information analysis system on the world flea fauna, hosted by the Zoological Institute of the Russian Academy of Sciences and supplemented regularly since 2001. At present, 28 flea species of 13 genera have been recorded for Karelia, amounting to about 35

Entomopathogenic fungi (EPF) play an important role in the density control of many arthropods in nature. The lethal effects of EPF on ixodid ticks (Ixodidae) have been mainly described for the warm-loving southern species that are mostly absent in Europe. We have performed a laboratory assessment of the virulence of 9 psychrotolerant EPF isolates of Beauveria bassiana s. l. (6), Akanthomyces cf. muscarius (2), and Metarhizium anisopliae s. l. (1) at a moderate mean daily temperature of +14°C against the overwintered adult taiga ticks Ixodes persulcatus, collected at the end of May in Kondopoga Province of the Republic of Karelia. All the tested isolates caused mortality in ticks at this temperature after infection with a concentration of 3 × 107 infectious spores per 1 mL. The most virulent and rapidly acting isolate was B. bassiana s. l. CCi-Ar (SI)14 from Arkhangelsk Province, Bolshoy Solovetsky Island (65°N, 35°E), killing 70

In 2019 and 2021, species composition of the ticks provided by citizens was studied at the Center for Hygiene and Epidemiology in the Republic of Karelia (based in Petrozavodsk). As a result, about 2 500 tick specimens were identified as belonging to the following species of the family Ixodidae: Ixodes persulcatus Schulze, 1930, I. ricinus (Linnaeus, 1758), Dermacentor marginatu s (Sulzer, 1776), D. reticulatus Fabricius, 1794, Hyalomma marginatum Koch, 1844, and Rhipicephalus sanguineus (Latreille, 1806). For 2% of the ticks, including all species not typically dwelling in Karelia, the attacks occurred outside of Karelia. For districts of Karelia, two species were identified: I. persulca tus (approx. 95% of all ticks delivered) and I. ricinus . Prevalence of pathogens in ticks as analyzed with the use of a commercial kit «AmpliSense® TBEV, B . burgdorferi sl, A . phagocytphillum , E . chaffeensis / E . muris - FL» based on real-time PCR. Prevalence of the tick-borne encephalitis virus in I. persulcatus was 1.5%. In I. ricinus ticks the virus was absent. The prevalence of the Borrelia burgdorferi s. l. and Ehrlichia spp. complex constituted 32.5 and 3.3% in I. persulcatus versus 16.3 and 0.8% in I. ricinus , respectively. A single occurrence of Anaplasma phagocytophillum was found in I. persulcatus (prevalence - 0.04%). The main determinant of the epidemiological situation in Karelia is the wide distribution and high abundance of I. persulcatus .

The aim of this study was to compare the parameters of the parasite species richness in common shrew Sorex araneus during the periods of its highest and lowest population abundance. The analysis was based on a comparative assessment of parasitic infracommunities and accumulation curves of helminth species richness. The significance of the observed differences was determined by analyzing the coefficients of the power regression equation modeling the dynamics of accumulation of species richness of parasitic communities. It has been shown that with an increase in the number of common shrews, there is a decrease in the average values of species richness of parasitic infracommunities, while their β-diversity increases. Differences in the accumulation curves of parasite species richness at low and high host abundance are determined by the peculiarities of the distribution of species richness in helminth infracommunities. During the period of relative depression in the number of S. araneus, the structure of parasite infracommunities was dominated by individuals with average values of species richness. During years of high shrew abundance, their population is characterized by a predominance of individuals with a poor species richness of parasites.

The water vole (Arvicola amphibius) is widespread throughout Eurasia. In 2020, 17 specimens were collected from the islands of the White Sea during the field expedition of the Karelian Research Centre. It was the first record of this species for White Sea island fauna since the 1950s. Among the captured voles, there were two different colour variants of the animals: almost black and reddish-brown. We tend to classify the black type of colour as melanism. This type of colouration is new for the species in the region, according to data from long-term monitoring of continental populations of small mammals. All reddish-brown samples, with the exception of one juvenile male, presented white spots on various parts of the body. The white-spotting patterns of reddish-brown colouration were also first recorded for water voles in the region. Individuals with different colouration types inhabited islands separated by about 50 kms of water.

The Cyathocotylidae Mühling, 1898 is a family of primitive diplostomoid trematodes important for understanding the evolution of the superfamily Diplostomoidea. However, cyathocotylids remain poorly studied with the use of molecular techniques. In this study we sequenced the 5.8S + ITS2 region, 28S rRNA , and cox1 genes of two cyathocotylid species and obtained new morphological data on them. We propose Georduboisia nom. nov. instead of the preoccupied name Duboisia Szidat, 1936 (junior homonym of Duboisia Stremme, 1911). Adults of Georduboisia cf. teganuma (Ishii, 1935) and Paracoenogonimus ovatus Katsurada, 1914 were collected from fish-eating birds in the south of the European part of Russia. Georduboisia cf. teganuma was very similar to G. teganuma but differed from it in the shape of the testes. The 28S rRNA gene dataset provided the best-resolved phylogeny of the Cyathocotylidae to date. In the phylogram based on partial sequences of this gene, P. ovatus was close to members of Holostephanoides Dubois, 1983, Neogogatea Chandler & Rausch, 1947 and Gogatea Szidat, 1936. Georduboisia cf. teganuma clustered with members of Cyathocotyle Mühling, 1896 and Holostephanus Szidat, 1936. Phylogenetic analysis based on the 5.8S + ITS2 dataset showed that adults of P. ovatus examined in our study were conspecific with the metacercariae from the musculature of fish collected in Hungary and Italy. It also revealed probable misidentifications of larvae and adults of cyathocotylids whose sequences are deposited in GenBank NCBI.

In nature, entomopathogenic fungi (EPF) play an important role in the control of population density in many arthropods. The lethal effects of EPF on ixodid ticks (Ixodidae) have been, however, reported mainly in southern warm-loving species, which are mostly not found in Europe. The aim of this study was to evaluate in laboratory the virulence of nine selected psychrotolerant EPF isolates of Beauveria bassiana s. l. (6), Akanthomyces cf. muscarius (2) and Metarhizium anisopliae s. l. (1) at a moderate average daily temperature of +14°C in relation to overwintering adult taiga ticks (Ixodes persulcatus), collected at the end of May in the Kondopoga region of the Republic of Karelia. Under this temperature, the use of suspensions for infection with a concentration of infectious spores (conidia) of 3×107 per 1 ml, all isolates showed a lethal effect on ticks. Among these isolates, the most virulent and rapidly acting one was B. bassiana s. l. CCi-Ar (SI)14 from the Arkhangelsk Province, Bolshoy Solovetsky Island (N 65°, E 35°), that killed 70% of specimens after 9 days, and 95% after 11 days. At the same time, it was found that male ticks have a slightly higher death rate from fungal infections. However, the potential suitability of some EPF isolates for biological control of I. persulcatus populations at low temperatures, shown in this study, requires confirmation in further tests in real conditions of recreational areas actively visited by humans, where infection with dangerous pathogens (tick-borne encephalitis, Lyme borreliosis) transmitted by tick bites often occurs.

В период с 16 по 20 октября 2023 г. в Петрозаводске на базе Карельского научного центра РАН состоялась Всероссийская конференция с международным участием «VII Съезд Паразитологического общества: Итоги и актуальные задачи». Тематика исследований охватывала широкий круг вопросов фундаментальной и прикладной паразитологии. В конференции приняли участие более 200 участников из различных регионов России, а также из Белоруссии, Вьетнама и Азербайджана. Работа съезда проходила в рамках пленарных и секционных заседаний по направлениям: экология и эволюция паразитов; паразитарные последствия глобальных изменений климата; морфофункциональные, молекулярные и биохимические аспекты паразито-хозяинных отношений; иммунный ответ при паразитарных инфекциях; биологические основы медицинской и ветеринарной паразитологии; паразиты растений, членистоногих, рыб, млекопитающих и птиц. Широко освещались достижения членов Общества в различных областях теоретической и прикладной паразитологии, было показано широкое внедрение современных методов исследований в систематике, экологии и эволюции паразитов животных и растений. Существенное внимание уделялось и анализу паразито-хозяинных отношений, включая их молекулярные аспекты, а также структуре и динамике формируемых паразитами популяций и сообществ.

Anopheles claviger (Meigen, 1804) (Diptera, Culicidae) is widespread in the western Palaearctic Region, but it was recorded in Karelia (Russia) for the first time. This record is one of the northernmost ones in the Palaearctic Region and Russia, updates the northern border of the An. claviger range. Mosquitoes were collected from July to September 2023 in the southern Karelia (the village of Gomselga, Kondopoga District, and Petrozavodsk) using Krishtal trap (from human) and Mosquito Magnet® trap (Pioneer design, Octenol as attractant). Seven females of An. claviger were collected in Gomselga; one specimen was sampled from Petrozavodsk City parks. Morphological identification of eight females was verified by COI and ITS2 sequences. Phylogenetic analysis of ITS2 and COI sequences confirmed the collected specimens to An. claviger s. s., clustering in both cases in a strongly supported clade clearly differentiated from the closely related species An. petragnani. The high diversity of An. claviger haplotypes from Karelia is in agreement with data from other geographical regions and shows that the records of this species in Gomselga and Petrozavodsk are not accidental.

The ecological concept of parasitism as a general biology phenomenon underlies the understanding of the role of parasites in terrestrial and aquatic ecosystems. The review gives an account of the current positioning of parasitology in the system of biological sciences, the subject and tasks of ecological parasitology. We relate the history of the science school in parasitology at the Institute of Biology KarRC RAS, which took shape under the leadership of pupils of the founder of the Russian school in ecological parasitology, outstanding scholar from Leningrad V. A. Dogiel. Major stages and areas of research and methodological approaches to the study of parasites and host-parasite relationships are described, covering a wide range of objects: blood-sucking arthropods, parasites of fish, birds, mammals, and plants. Studies deal with the formation and dynamics of parasitic communities in natural and disturbed terrestrial and aquatic ecosystems (eutrophication, industrial pollution, alien species invasions, aquaculture). The results of these studies are of high theoretical significance and have been published in monographs and in articles in Russian and international journals. Practical recommendations are widely applied in nature management, veterinary and agricultural practices, and are annually published in the Republic of Karelia State Report on the Environment. Today, the science school in ecological parasitology in Karelia is represented by qualified specialists, who investigate a wide range of both basic and applied topics, including those of special relevance for the region.

The taiga tick Ixodes persulcatus (Schulze, 1930) (Acari, Ixodidae) is the main vector of the tick-borne encephalitis virus and one of the most widespread species of ixodid ticks in the Palaearctic. In this paper, we present long-term data on the seasonal activity of adult ticks in the north-west of their distribution. The seasonal activity of Ixodes persulcatus was studied from 1982 to 1990 and from 2012 to 2023 in the middle taiga subzone of Karelia (N62.0697, E33.961). In the study area, adult ticks I. persulcatus demonstrate a pronounced spring-summer activity with a unimodal curve of abundance change. A comparison of the monitoring data from the 1980s and the 2010s showed a significant increase in the abundance of I. persulcatus in the study area. A tendency towards an earlier start of the tick activity, as compared to the 1980s, is now being observed.

In this study, we tested the applicability of three common methods of absolute abundance estimation-Peterson, Bailey and Jolly-Seber-to Ixodes persulcatus ticks based on mark-release-recapture data. The ticks were collected by flagging during the seasonal activity peak of the ticks in the mid-taiga zone of Karelia (62.0697°N, 33.9614°E). In total, 108 females and 92 males of I. persulcatus were marked. The marked individuals were captured 161 times before the end of the study period with their proportion in the samples reaching 50%. Females were recaptured more often than males, 105 versus 56 times. Estimates of adult tick abundance ranged from 0.4 to 2 specimens per m2 depending on the calculation method. The obtained estimates of absolute abundance varied unpredictably depending on the length of the intervals between capture sessions and showed no significant correlations with the number of ticks collected by flagging. The choice of the method of tick abundance estimation mainly depends on the study aims. The Petersen method may be useful for quick estimates of local tick abundance, whereas the Jolly-Seber method allows an estimation of the absolute abundance during the entire period of the tick activity. Individual marking of ticks may improve the accuracy of the estimates.

Ixodid ticks (Acarina, Ixodidae) are vectors of dangerous human infections. The main tick species that determine the epidemiological situation for tick-borne diseases in northern Europe are Ixodes ricinus and Ixodes persulcatus. In recent years, significant changes in the number and distribution of these species have been observed, accompanied by an expansion of the sympatric range. This work summarizes the data of long-term studies carried out in Karelia since 2007 on the infection of I. persulcatus and I. ricinus ticks with various pathogens, including new viruses with unclear pathogenic potential. As a result, tick-borne encephalitis virus (TBEV, Siberian genotype), Alongshan virus, several representatives of the family Phenuiviridae, Borrelia afzelii, Borrelia garinii, Ehrlichia muris, Candidatus Rickettsia tarasevichiae and Candidatus Lariskella arthropodarum were identified. Data were obtained on the geographical and temporal variability of tick infection rates with these main pathogens. The average infection rates of I. persulcatus with TBEV and Borrelia burgdorferi sensu lato were 4.4% and 23.4% and those of I. ricinus were 1.1% and 11.9%, respectively. We did not find a correlation between the infection rate of ticks with TBEV, B. burgdorferi s.l. and Ehrlichia muris/chaffeensis with the sex of the vector. In general, the peculiarities of the epidemiological situation in Karelia are determined by the wide distribution and high abundance of I. persulcatus ticks and by their relatively high infection rate with TBEV and B. burgdorferi s.l. in most of the territory, including the periphery of the range.

Metacercariae of Diplostomum petromyzifluviatilis (Digenea, Diplostomidae) from the brain of European river lamprey Lampetra fluviatilis from the Baltic Sea basin and Arctic lamprey Lethenteron camtschaticum from the White Sea basin were studied with the use of genetic and morphological methods. Phylogenetic analysis based on cox1 marker showed that the parasites of both lamprey species were conspecific with Diplostomum sp. Lineage 4 of Blasco-Costa et al. (2014). The name Diplostomum petromyzifluviatilis Müller (Diesing, 1850) has historical precedence as a species described from the brain of lampreys and should be used in genus nomenclature. There were no morphological qualitative differences between the metacercariae from the two lamprey species but those from L. fluviatilis were larger than those from L. camtschaticum. We expanded the data on the second intermediate hosts and the localization of D. petromyzifluviatilis, showing that its metacercariae occur not only in the brain of lampreys but also in the brain and the retina of three-spined stickleback Gasterosteus aculeatus and the vitreous humour of the perch Perca fluviatilis across the European part of the Palearctic.

This paper presents comparative assessment of the timing of host abandonment by different taxa of ectoparasites of small mammals after the host has been captured in a regular snap trap. The data were obtained using a specially designed trap line with automatic logging of the capture time. Our results generally support the basic rule that ectoparasites eventually abandon the dead host. The most tangible and rapid reduction in infection rates following host death was observed in Ixodes persulcatus. Fleas and parasitic gamasid mites abandoned the host in 2–4 h, and lice, in 9–13 h after snap-trapping. Ixodes trianguliceps displayed no sharp decline in abundance for a prolonged period of time.

Ixodes ricinus and Ixodes persulcatus ticks are the main vectors of tick-borne encephalitis virus and some bacterial pathogens. The regions where these tick species live overlap, forming large sympatric areas. It has previously been shown that these tick species have no morphological barrier, and interspecies crossing is possible with the appearance of sterile hybrids. It has also been shown that hybrid larvae and nymphs can be differentiated using discriminant functions based on a set of morphological features. However, such an approach is laborious and rather ineffective with adult ticks, making a molecular approach necessary. In the current work, we tested the ability of different systems to differentiate laboratory-obtained hybrid ticks. Our data suggest that commonly used primer sets that target rRNA are unsuitable for hybrid tick determination, likely due to the rRNA region being linked with the X chromosome in I. ricinus and I. persulcatus ticks. We tested several primer sets targeting different non rRNA genes to assess their ability to determine hybrids. The best primer set, Toll_R, targeting the putative Toll gene, showed little to no bias when used for DNA amplification from hybrid ticks. Thus, Toll gene can be further used for hybrid detection.

The article describes the structure and methods of filling and using the information system created to accumulate data from long-term surveys of small mammals at the Gomselga Biological Research Station of the Institute of Biology KarRC RAS. The data obtained in the period from 1994 to 2022 total 5404 records on individual animals and 668 records on sampling lines. The relational database on small mammals is linked to the GIS which maps of the spatial distribution of animal habitats and the locations of sampling lines. The information system permits storing different types of data in separate interlinked tables which make the source material more visual and easily verifiable. Data are shared between different program environments using the simple csv format. The database and GIS tables are linked via a composite key field facilitating accurate matching of objects (individuals) to unique samples (lines). To acquire a certain subset the user makes a multistage query which is both easily editable and enables control at each stage of data selection and integration. The proposed structure of the information system is universal in nature and applicable whenever series of samples are collected simultaneously in a given locality. The system can be used in the MS Excel, Access, LO Calc, Base, R, and QGIS program environments. The formats of data presentation in tables and links between tables and GIS layers are discussed; the structure and types of queries are presented. Sample queries for acquiring data for subsequent processing by quantitative methods and for illustrations are provided.