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The article dwells upon characteristics of the species richness of parasite communities in least cisco Coregonus sardinella Valenciennes in Polar water bodies: Kureyskoye Reservoir, Lake Kutaramakan, Khatanga River. The communities consist of parasite species common in coregonids. The main species in all the parasite communities in least cisco are Dibothriocephalus ditremus and D. dendriticus . Triaenophorus crassus plerocercoids dominate in the regulated water body (Kureyskoye Reservoir). To analyze the species richness of the component communities (s), coefficients of the power-law equation s  =  a  ×  n b were applied, where a is the expected species richness in the first host individual examined, and b is the rate of species accumulation in parasite component communities ( s ). The resulting curves of species accumulation give statistical rigor to the assessment of differences and similarities of the species richness of the component communities of parasites in least cisco of various ages and habitats. The species richness of infra- and component parasite communities in least cisco was found to be significantly lower in the lake and the storage reservoir than in riverine habitats (Khatanga River). At the same time, the species accumulation rate for parasite communities in least cisco from Lake Kutaramakan was higher than in the reservoir due to a higher diversity of parasite infracommunities.

The Menetries’ Tiger Moth Arctia menetriesii can be considered a prospective umbrella/indicator/flagship species for conservation programs, highlighting primeval Eurasian taiga forests. To examine its inter-annual population dynamics, host plants, habitat preferences and phenology, a dataset from field surveys and experimental research was compiled. The species’ rarity may be, at least partly, an artifact of its low detectability in nature due to its preference for hard-to-reach areas, short flight period of the imago, and, perhaps, limited daily activity. The natural survival patterns of A. menetriesii are still unknown but in breeding experiments maximum mortality occurred at the larval stage (mean ± S.E. = 84.6 ± 6.2%; n = 7). This estimate does not take into account the potential impact of parasitoids, predators, and floods that may also decrease the total abundance of A. menetriesii . Moreover, several limiting factors may contribute to the extreme rarity of this species: climate influence, dependence on toxic host plants, fungal disease and desiccation in overwintering larvae. Our research indicates that there are clear differences between European and Asian populations of the species. In Europe, it occurs more rarely, in odd years, and with restricted latitudinal, elevational, and habitat ranges, perhaps due to the founder effect. Our findings reveal that long-term series of A. menetriesii annual captures do not align with the global trend of insect declines. Further research is necessary to create a climatic niche model and to assess possible range shifts under past and future climate scenarios.

Global environmental changes may cause dramatic insect declines but over century-long time series of certain species’ records are rarely available for scientific research. The Menetries’ Tiger Moth (Arctia menetriesii) appears to be the most enigmatic example among boreal insects. Although it occurs throughout the entire Eurasian taiga biome, it is so rare that less than 100 specimens were recorded since its original description in 1846. Here, we present the database, which contains nearly all available information on the species’ records collected from 1840s to 2020. The data on A. menetriesii records (N = 78) through geographic regions, environments, and different timeframes are compiled and unified. The database may serve as the basis for a wide array of future research such as the distribution modeling and predictions of range shifts under climate changes. It represents a unique example of a more than century-long dataset of distributional, ecological, and phenological data designed for an exceptionally rare but widespread boreal insect, which primarily occurs in hard-to-reach, uninhabited areas of Eurasia.Measurement(s)specimen record • biological parameters of specimen • environmental characteristics • sampling date • habitat image • specimen imageTechnology Type(s)digital curationFactor Type(s)year • month • ten-day period • day • geographic location • altitude • habitat • landscape type • presence of waterbody • ecoregion • developmental stage • sex • individual conditionSample Characteristic - OrganismMenetries’ Tiger Moth Arctia menetriesii (Insecta: Lepidoptera: Erebidae)Sample Characteristic - Environmenttaiga biome • high-altitude environmentSample Characteristic - LocationNorthern Eurasia

Aggregation is a fundamental feature of parasite distribution in the host population, but the biological implications of the aggregation indices used to describe the relationships between the populations of parasites and hosts are not evident. It is speculated that the form of distribution in each case is predicated on the host’s varying resistance to the infection, which is hard to control, making it difficult to adequately interpret the index values. This paper examines several cases from trout farms in Russian Karelia to explore the monogenean Gyrodactylus spp. infection in rainbow trout of varying ages. The genetic homogeneity of cage-reared fish and the direct life cycle of the helminths make the relationship between the species more lucid than in natural host-parasite systems. The results give no ground to speak of any specific patterns: as well as in the natural systems, the infection rates in trout vary widely, i.e., the helminth distribution has not become more uniform; the observed distributions in all cases are adequately approximated by the negative binomial model; the positive abundance-occupancy relationships (AORs) and abundance-variance relationships (AVRs) common for parasitic systems apply to the basic infection parameters. The form of the negative binomial distribution is shaped by two parameters— k and θ , the former being a metric of the infection variability, which depends on the host’s individual resistance, and the latter representing the parasites’ reproduction and establishment success rates. A rise in the parameter k indicates increased aggregation and a higher parameter θ points to a more uniform frequency distribution. These parameters can be used as a representative tool for monitoring the parasite communities in salmonid fishes, including in aquaculture.

Pink salmon, Oncorhynchus gorbuscha (Walbaum, 1792), a native of the North Pacific Ocean, is an invasive fish species rapidly expanding in the North Atlantic, the adjacent waters of the Arctic Ocean, and rivers in their watersheds. We investigated the species composition of parasites and the structure of parasite communities of the introduced pink salmon in Kandalaksha Bay of the White Sea in 2021. The parasites were identified using morphological and genetic methods. A total of 14 parasite species were recorded. The core species of the parasitic fauna of the introduced pink salmon in the Kandalaksha Bay were Clistobothrium sp., ʽDiphyllobothriumʼ spp., Scolex polymorphus Rudolphi, 1819 (plerocercoids), Brachyphallus crenatus (Rudolphi, 1802), Derogenes varicus (Müller, 1784), Lecithaster salmonis Yamaguti, 1934 (adults), Anisakis simplex (Rudolphi, 1809) sensu stricto (juvenile III), and Hysterothylacium aduncum (Rudolphi, 1802) (juveniles III and IV). We provided the first evidence that the Pacific genetic lineage of A. simplex sensu stricto occurs in European marine waters. In 2021, there was a noticeable increase in the mean abundance of the third-stage juveniles of Anisakis in the White Sea pink salmon compared to the period of 1990s-early 2000s. We conclude that the pink salmon occupies the same trophic niche in the new region of its introduction as in the native range.