Bank Voles Research Articles

The timid invasion: behavioural adjustments and range expansion in a non-native rodent.

Animal behaviour can moderate biological invasion processes, and the native fauna's ability to adapt. The importance and nature of behavioural traits favouring colonization success remain debated. We investigated behavioural responses associated with risk-taking and exploration, both in non-native bank voles (Myodes glareolus, N = 225) accidentally introduced to Ireland a century ago, and in native wood mice (Apodemus sylvaticus, N = 189), that decline in numbers with vole expansion. We repeatedly sampled behavioural responses in three colonization zones: established bank vole populations for greater than 80 years (2 sites), expansion edge vole populations present for 1-4 years (4) and pre-arrival (2). All zones were occupied by wood mice. Individuals of both species varied consistently in risk-taking and exploration. Mice had not adjusted their behaviour to the presence of non-native voles, as it did not differ between the zones. Male voles at the expansion edge were initially more risk-averse but habituated faster to repeated testing, compared to voles in the established population. Results thus indicate spatial sorting for risk-taking propensity along the expansion edge in the dispersing sex. In non-native prey species the ability to develop risk-averse phenotypes may thus represent a fundamental component for range expansions.

Cross-reactivity of T cell-specific antibodies in the bank vole (Myodes glareolus)

The bank vole is a common Cricetidae rodent that is a reservoir of several zoonotic pathogens and an emerging model in eco-immunology. Here, we add to a developing immunological toolkit for this species by testing the cross-reactivity of commercially available monoclonal antibodies (mAbs) to the bank vole lymphocyte differentiation molecules and a transcription factor. We show that a combination of mAbs against CD4, CD3, and Foxp3 allows flow cytometric distinction of the main subsets of T cells: putative helper CD4+, cytotoxic CD8+ (as CD3+CD4-) and regulatory CD4+Foxp3+. We also provide a comparative analysis of amino acid sequences of CD4, CD8αβ, CD3εγδ and Foxp3 molecules for a number of commonly studied Cricetidae rodents and discuss mAb cross-reactivity patterns reported so far in this rodent family. We found that in case of mAbs targeting the extracellular portions of commonly used T cell markers, sequence similarity is a poor prognostic of cross-reactivity. Use of more conserved, intracellular molecules or molecule fragments is a more reliable approach in non-model species, but the necessity of cell fixation limit its application in, e.g. functional studies.

Cases of Hemorrhagic Fever with Renal Syndrome in Russia during 2000–2022

During 2000–2022, a total of 69 of Russia’s 85 administrative regions reported 164,580 hemorrhagic fever with renal syndrome (HFRS) cases, with an annual average rate of 4.9 cases/100,000 population (105 popul.). European Russia reported 162,045 (98.5%) cases in 53/60 regions with 9.7 cases/105 popul. Asian Russia reported 2535 (1.5%) cases in 16/25 regions with 0.6 cases/105 popul. In the same period, Russia reported 668 (0.4%) fatal HFRS cases, and 4030 (2.4%) cases among children under the age of 14 years. Most HFRS cases occurred during autumn and winter. The incidence among rural residents was 6.7 per 105 popul., higher than the urban 4.4 per 105 popul.; however, among HFRS patients, rural and urban residents account for 35% and 65%, respectively. Six hantaviruses, causing HFRS of different clinical severity, were recognized as pathogens: Hantaan (HTNV) and Amur (AMUV) of Orthohantavirus hantanense species, Seoul (SEOV) of Orthohantavirus seoulense species, Puumala (PUUV) of Orthohantavirus puumalaense species, and Kurkino (KURV) and Sochi (SOCV) of Orthohantavirus dobravaense species, with the principal hosts Apodemus agrarius coreae, Apodemus peninsulae, Rattus norvegicus, Myodes glareolus, Apodemus agrarius agrarius, and Sylvaemus ponticus, respectively. It was found that 97.7% of HFRS cases are caused by PUUV, therefore, this virus plays the main role in the HFRS morbidity structure in Russia.

PECULIARITY OF MARKER GENES’ EXPRESSION IN BANK VOLES CLETHRIONOMYS GLAREOLUS CHARACTERIZING ECOTOXICITY EFFECTS OF THE TERRITORY CONTAMINATED WITH DIOXINS

To assess the ecotoxicity of low doses of dioxins is almost impossible without considering the in uence of real exposure conditions on these substances’ properties. The best approach to take these into account is the biomonitoring of the initial toxic e ects’ manifestation. We studied bank voles from population naturally exposed to dioxins, the summer-born adults and overwintered functional groups of animals di ered by dioxin body burden. Dioxin-free samples of a vivarium bank voles’ line served as a control. Initial e ects of ecotoxicity were characterized by transcriptional levels of genetic markers: ahr, cyp1a2, keap1, dnmt1, dnmt3a, dnmt3b, LINE-1 and B1-SINE. Summer-born functional group had signi cantly higher expression levels of ahr, keap1, dnmt3a and dnmt3b genes versus their control group. Overwintered functional group had elevated expression levels of cyp1a2 and keap1, but no changes were found versus controls for dnmt1, LINE-1 and SINE B1. The increased expression of marker genes in dioxin-exposed voles was quite well associated with toxic process’ mechanisms - their formation and progression under exposure of several generations to low sub-toxic doses. The data obtained will contribute to the development of a biomonitoring method for assessing the initial e ects of dioxin ecotoxicity.

VKORC1-based resistance to anticoagulant rodenticides widespread in Finnish house mice but not in brown rats

Anticoagulant rodenticide (AR) resistance is widespread across Europe, but its prevalence has not been previously studied in Finland. We sampled 48 house mice (Mus musculus) and 48 brown rat (Rattus norvegicus) in farms and urban locations from southern Finland and here we report the identification of Vkorc1 polymorphisms linked to AR resistance. Two thirds of mice carried Vkorc1 polymorphisms. The most common was the type Y139C (resistance to first-generation ARs, bromadiolone and difenacoum), whereas the type L128S (resistance to FGARs and bromadiolone) was much less abundant. Only two rats tested positive, both with a rare type R33P (resistance probably to warfarin). No clear patterns based on subregion, sex and urban/rural division were seen. We suggest that the type Y139C polymorphism should be taken into account when planning control actions targeting house mice in Finland. The low number of AR resistant rats found suggests a low prevalence of resistance in rats. To fully understand the state of AR resistance in Finland, additional studies on yellow-necked mouse (Apodemus flavicollis) and bank voles (Myodes glareolus) are needed.

Presence and identity of Babesia microti in Ireland

Babesia microti is a tick-transmitted protozoan parasite of wildlife that can also cause serious disease in humans. It is now well established that B. microti represents an assemblage of different strains or species, only some of which are important zoonotic pathogens. Therefore, in order to assess the potential public health risk associated with B. microti in any given location, it is important to determine the strains that are present. This is the first study on the presence and identity of B. microti in Ireland. Overall, 314 wood mice (Apodemus sylvaticus), 243 bank voles (Myodes glareolus) and 634 questing Ixodes ricinus nymphs collected in various locations across Ireland were screened for the presence of B. microti by metabarcoding and nested PCR, respectively. Overall 8 rodent spleen samples (1.4%) were positive for B. microti, while all tick samples tested negative. Rodent isolates were identified as the ‘Munich’ strain which rarely causes human disease and is chiefly transmitted by the mouse tick, Ixodes trianguliceps. Together with reports from the UK these results suggest that B. microti does not represent a significant public health risk in Britain or Ireland.

So many choices, so little time: Food preference and movement vary with the landscape of fear.

Spatial and temporal variation in perceived predation risk is an important determinant of movement and foraging activity of animals. Foraging in this landscape of fear, individuals need to decide where and when to move, and what resources to choose. Foraging theory predicts the outcome of these decisions based on energetic trade-offs, but complex interactions between perceived predation risk and preferences of foragers for certain functional traits of their resources are rarely considered. Here, we studied the interactive effects of perceived predation risk on food trait preferences and foraging behavior in bank voles (Myodes glareolus) in experimental landscapes. Individuals (n = 19) were subjected for periods of 24 h to two extreme, risk-uniform landscapes (either risky or safe), containing 25 discrete food patches, filled with seeds of four plant species in even amounts. Seeds varied in functional traits: size, nutrients, and shape. We evaluated whether and how risk modifies forager preference for functional traits. We also investigated whether perceived risk and distance from shelter affected giving-up density (GUD), time in patches, and number of patch visits. In safe landscapes, individuals increased time spent in patches, lowered GUD and visited distant patches more often compared to risky landscapes. Individuals preferred bigger seeds independent of risk, but in the safe treatment they preferred fat-rich over carb-rich seeds. Thus, higher densities of resource levels remained in risky landscapes, while in safe landscapes resource density was lower and less diverse due to selective foraging. Our results suggest that the interaction of perceived risk and dietary preference adds an additional layer to the cascading effects of a landscape of fear which affects biodiversity at resource level.

Evolutionary Formation and Distribution of Puumala Virus Genome Variants, Russia.

We analyzed Puumala virus (PUUV) sequences collected from bank voles from different regions of Russia. Phylogenetic analysis revealed PUUV reassortments in areas with the highest hemorrhagic fever with renal syndrome incidence, indicating reassortment might contribute to pathogenic properties of PUUV. Continued surveillance is needed to assess PUUV pathogenicity in Russia.

Significance of Intestinal Helminth Infection and Animal Sex for Mercury Concentrations in Two Rodent Species.

We compared the effects of animal gender, species, and intestinal helminth burden on mercury concentrations in rodents. Total mercury concentrations were determined in the liver and kidney tissues of 80 small rodents (44 yellow-necked mice, Apodemus flavicollis, and 36 bank voles, Myodes glareolus) captured in the Ore Mountains (northwest Bohemia, Czech Republic). Overall, 25/80 (32%) of animals were infected by intestinal helminths. The differences in mercury concentration between rodents infected and not infected with intestinal helminths were not statistically significant. Statistically significant differences in mercury concentrations were found only between voles and mice (that were not infected with intestinal helminths). This suggests the differences may be associated with host genetics. Apodemus flavicollis body tissues had significantly lower (P=0.01) mean Hg concentrations (0.032 mg/kg) than Myodes glareolus (0.279 mg/kg), provided that animals were not infected by intestinal helminths; if the animals were infected by intestinal helminths, the difference between both groups was insignificant. The effect of gender in this study was significant only for voles (without helminth infection); for mice (either with or without helminth infection) the differences between genders were not significant. Myodes glareolus males had significantly lower (P=0.03) Hg concentrations in liver and kidney tissues (0.050 mg/kg) than Myodes glareolus females (0.122 mg/kg). These results reveal the importance of considering species and gender when evaluating mercury concentrations.

МОДЕЛЮВАННЯ ЧИСЕЛЬНОСТІ ГРИЗУНІВ У ЛІСОВИХ БІОТОПАХ ЗАХІДНОГО ПОДІЛЛЯ (НА ПРИКЛАДІ MYODES GLAREOLUS)

Monitoring and predicting the dynamics of abundance of species living in natural habitats is an important component stability analysis of ecosystem as well as dynamics and direction of change of biotic communities under global climate change and pressure of the alien species. The aim of the work was to build a matrix model and study the state of stabilisation of the dynamics of the bank vole population within the Leslie model. The object of the study was the population dynamics of Myodes glareolus Schreber, 1780 = Clethrionomys glareolus auct. The study is based on materials obtained during 2017–2019. This period covered one phase of the long-term population dynamics of the bank vole, named “population growth”. The research was carried out according to generally accepted methods. A total of 6400 trap-days were processed, and 358 forest fistulas were collected and studied. The intensity of harmful activity of rodents is due to the variability of the number of animals in the population. The quantitative population changes are the result of three factors: births, deaths, and migrations. The main condition for the existence of the species is the stability of the population, which is determined by the action of thecompensatory mechanisms. The growth phase of the bank vole lasted all three years of the research, the quantitative indicators were respectively: 2017 – 1.8 individuals per 100 trap-days; 2018 – 2.0 individuals per 100 trap-days; 2019 – 2.7 individuals per 100 trap-days. Low levels of the abundance in the spring of each year of the study, namely at the beginning of the breeding season (3.7 – 2.6 – 8.9 individuals per 100 trap-days). Favourable for the abundance growth was the sex ratio of the population (approximately 1:1), with some rise in the share of females, which decreases on the period of spring 2018 to autumn 2019). Some decrease in the share of immature individuals (4.5 – 3.9 – 3.1 %) is an indirect confirmation of the stability of puberty of animals with subsequent replenishment of the "stock", which led to accelerated reproduction and, consequently, provided prerequisites for further population growth. The causal mechanisms of population control established by us, without a doubt, can serve as a basis for further prognosis, of the number of pests in natural habitats. To predict population changes, the Leslie model, which is widely used in mathematical analyses of the abundance of both plant and animal groups, was chosen. The algorithm for building a matrix model, detailed in the article, has five following steps. The exponential nature of the actual and projected growth of the bank vole population during the five-year cycle (2017–2019 with a prognosis until 2023) revealed in the analysis can be explained not so much by the power of the species' reproductive potential as by the lack of the significant changes in habitat, caused by constant weather conditions, low individual mortality from predators and non-communicable diseases or other accidents. The application of the matrix model allowed to confirm the key role of the main compensatory mechanisms of population dynamics, as they contribute to the stabilisation of the population and, as a consequence, are an important condition for the existence of the species.

Features of craniological signs of <i>Myodes glareolus</i> Schreber in the Kostroma Region

As part of the comprehensive monitoring of the state of the ecosystems of the Reserve Kologrivsky Les, studies of the Myodes glareolus Schreber population organization were conducted for eleven years (20122022). To compare the values of craniological signs of the control population, similar measurements were considered in rodents living on the territory of Minskoe forestry in the Kostroma Region (20212022). The paper provides data on the size and proportions of the skull of this species. Osteological indices characterizing the nutrition ecology of the studied populations and their craniometric appearance were calculated. The variability and correlation of 17 craniometric signs of Myodes glareolus was analyzed in order to diagnose the degree of optimality of conditions for the existence of this species populations, as well as to assess the state of the environment in complex biological monitoring programs. Data were obtained on the patterns of variability of metric and nonmetric features of the skull in a number of years, and the influence of the sex structure of the population, the dynamics of its population, weather and climatic factors on the determinism of craniological measurements was studied. Sexual dimorphism according to these parameters was expressed slightly. There was a positive correlation of signs in rodents living on the territory of the biosphere reserve as the most optimal habitat in comparison with the territory of Minskoe forestry in the Kostroma Region, where a negative correlation was predominantly revealed. A strong correlation was established between some craniometric features characterizing the specifics of nutrition, population density, average precipitation and average air temperature. In addition, weak correlations between the body weight of individuals and the dimensions of the skull were revealed. When studying the fluctuating asymmetry of non-metric features of the left and right sides of the upper and lower jaw, a low level of the FAnm coefficient was found in the studied populations. Dynamic changes in the level of fluctuating asymmetry of rodents were insignificant. A weak negative correlation of the fluctuating asymmetry and the values of the average precipitation during the study periods were established. No significant correlation was established for the other factors. The results of the presented comprehensive study of the craniometric features of Myodes glareolus on the territory of the Kostroma Region indicate a stable state of populations in the considered environmental conditions.

Protozoan Parasites of Sarcocystis spp. in Rodents from Commercial Orchards

Small mammals are an important group of wildlife that can transmit pathogens to humans and animals. There is a lack of comprehensive studies on the protozoan parasites of the genus Sarcocystis in agricultural areas. The aim of the current research was to evaluate the prevalence of Sarcocystis spp., and to identify the parasite species found in the skeletal muscles of rodents and insectivores from commercial orchards. A total of 679 muscle samples from small mammals, mainly rodents (n = 674), belonging to eight species were examined. Muscle samples were pooled into groups, then digested, and the presence of the Sarcocystis species was confirmed by molecular methods. The examined parasites were determined in five rodent species, Apodemus agrarius, A. flavicollis, Clethrionomys glareolus, Microtus arvalis, and M. oeconomus. The prevalence of Sarcocystis spp. was low: 2.23% in voles and 0.79% in mice. Based on a sequence comparison of cox1 and 28S rDNA, four species were identified: S. myodes, Sarcocystis cf. strixi, Sarcocystis sp. Rod1, and Sarcocystis sp. Rod2. This is the first report of S. myodes in A. agrarius, A. flavicollis, and M. arvalis. The identified species were most closely related to Sarcocystis spp., and were transmitted by predatory mammals and birds. Future studies are needed to describe the species morphologically, as well as to define the host spectrum and to evaluate their possible pathogenicity.

Factors that affect long-distance movements of small rodents and shrews in the Ural taiga: disentangling dispersal from excursion movements

Abstract Long-distance movements (LDMs) of small mammals (SMs) are complex phenomena that cover both dispersals and excursions occurring outside the home ranges of individuals. Owing to methodological difficulties, there are a lack of data on LDMs for SMs. In this study, we aimed to determine the factors that influence the LDMs of different mouse-sized rodents and shrews in the Ural taiga (Sverdlovsk region, Russia). We conducted a field experiment in a boreal forest using individual- (capture–marking–recapture [CMR]) and group- (biomarkers: tetracycline and rhodamine B) marking methods, in conjunction with additional feeding. The species, sex, maturity, plot ID, additional food supply, species abundance indices, individuals/100 trap-nights indices in the capture plot, and body weight of each animal were analyzed as predictors of LDMs. We identified 89 individuals from six species that moved at distances of 250, 350, and 500 m. LDMs varied with the particular species and its population abundance. Most of the observed movements were excursions and not dispersal events. Applying mathematical simulations to the obtained empirical data facilitated estimation of the intensity of the excursion activity for different species. We present the 1st excursion data on Sylvaemus uralensis (Pallas, 1811), Microtus arvalis (Pallas, 1778), and Sorex caecutiens (Laxmann, 1788). The detected excursion distance (250 m) for Myodes glareolus (Schreber, 1780) is the maximum excursion distance known for this species. We demonstrate that with comparable labor and time costs, the use of biomarkers makes it possible to detect many more LDMs than CMR allows.

Balancing selection on the complement system of a wild rodent

BackgroundSelection pressure exerted by pathogens can influence patterns of genetic diversity in the host. In the immune system especially, numerous genes encode proteins involved in antagonistic interactions with pathogens, paving the way for coevolution that results in increased genetic diversity as a consequence of balancing selection. The complement system is a key component of innate immunity. Many complement proteins interact directly with pathogens, either by recognising pathogen molecules for complement activation, or by serving as targets of pathogen immune evasion mechanisms. Complement genes can therefore be expected to be important targets of pathogen-mediated balancing selection, but analyses of such selection on this part of the immune system have been limited.ResultsUsing a population sample of whole-genome resequencing data from wild bank voles (n = 31), we estimated the extent of genetic diversity and tested for signatures of balancing selection in multiple complement genes (n = 44). Complement genes showed higher values of standardised β (a statistic expected to be high under balancing selection) than the genome-wide average of protein coding genes. One complement gene, FCNA, a pattern recognition molecule that interacts directly with pathogens, was found to have a signature of balancing selection, as indicated by the Hudson-Kreitman-Aguadé test (HKA) test. Scans for localised signatures of balancing selection in this gene indicated that the target of balancing selection was found in exonic regions involved in ligand binding.ConclusionThe present study adds to the growing evidence that balancing selection may be an important evolutionary force on components of the innate immune system. The identified target in the complement system typifies the expectation that balancing selection acts on genes encoding proteins involved in direct interactions with pathogens.

The use of boreal relict shrub habitats of willow-leaf meadow sweet (Spiraea salicifolia) and shrubby cinquefoil (Potentilla fruticosa) in Western Rhodope Mts. by mammal species

Plant communities of two peat-shrub species – Spiraea salicifolia and Potentilla fruticosa were studied in the Rhodope Mts., with emphasis on their use as a resource for the mammals associated with them. These shrubs are boreal relicts among the dominant coniferous forests. The field surveys were conducted in the spring-autumn period of 2021–2022. In both study areas, the species composition of the mammals was studied by camera traps for medium and large mammals, and by Sherman live traps for small mammals. The species registered were roe deer (Capreolus capreolus), red fox (Vulpes vulpes), wild boar (Sus scrofa), pine marten (Martes martes), European hare (Lepus europaeus), red squirrel (Sciurus vulgaris), bank vole (Myodes glareolus) and yellow-necked mouse (Apodemus flavicollis). Having in mind that small mammals are vital prey base for avian and mammalian predators, it is not surprising that M. glareolus and A. flavicollis individuals were captured in the habitats that they probably use as shelters. The pine marten inhabits the forests by which the community of P. fruticosa is surrounded, but probably feeds on the rodents in the shrub. In this way, it probably provides it with an alternative to the forest food base and hunting ground. From the presented results, it seems that the L. europaeus uses P. fruticosa shrubs as food. Therefore, the plant communities of the two relict peat-shrub species studied probably provide shelter and food for the mammals. Their importance is established for at least one species of mammal with conservation significance at national and European level – M. martes. Therefore, it is necessary to continue and expand the future monitoring on mammal diversity of these relict communities.

First description of nymphal stages of Hoplopleura edentula (Anoplura: Hoplopleuridae) and a global checklist of the Hoplopleura associated with Clethrionomys

Abstract We present the first record of the characteristics of the three nymphal stages of Hoplopleura edentula, one of the common Eurasian species of the genus Hoplopleura. Lastly, a list of all species of Hoplopleura parasitizing the host genus Clethrionomys is provided. The descriptions of sucking louse species usually lack the features of the nymphal stages. In addition, it is impossible to determine whether the host is the main one or an accidental when there is a co-occurance of two or more lice species, unless we observe nymphs of the same species. As a result, data on the host cycle, the range of host specificity and other aspects of parasite-host system functioning, the possibility of transfer between hosts, and the possibility of transmission of pathogens, are incomplete. This study examines 114 specimens of the bank vole Clethrionomys glareolus, in which 38 Hoplopleura edentula were found.

Abundance and Condition of Populations of Small Mammals as Carriers of Natural Focal Human Diseases in the Karelia North-East Ladoga

Summing up the results of the long-term studies of population ecology and dynamics of small mammals for more than half a century (1966–2018). Small mammals are involved in the formation and functioning of natural-focil of human vector-borne diseases common in the North-Eastern Ladoga region. Encephalitis and tularemia circulate intensively in the Ladoga region under conditions of intensive anthropogenic transformation of taiga ecosystems. Local landscapes belong to the subzone of the middle taiga forests. Most of the studied species of small mammals are located in the northern periphery of this area. Here representatives of the native taiga fauna of Micromammalia constantly experience powerful anthropogenic pressure, which leads to a decrease in their abundance and correlation of the species. Of the total amount of 22 species of small mammals collected here, Sorex araneus and Myodes glareolus dominate. Next, the species prevalent (according to the degree of predominant species) in the counts are Microtus agrestis, Sorex minutus and Sorex caecutiens. Other species are relatively rare and appear in smaller numbers. Myodes glareolus has main role in the feeding of ticks and, accordingly, in the circulation of infections in nature, the differentiated contribution of individual intrapopulation groups in maintaining the number of vectors and the activity of pathogens. Shrews are important for the development of the larval stages of the tick. In the research area, were recorded total index of trap catch of abundance of small animals with trap lines from 0.34 to 18.5 individuals per 100 snap traps-nights (average of 7.8 ind.) and with pitfall traps recorded from 2.7 to 25.4 individuals per 10 ditch-nights (average of 14 ind.). This indicates that the studied area has smaller amount of mammals compared to other regions in Southern Europe. Nevertheless, the studies determine a rather tense epidemic situation in the studied area. Population of small mammals of boreal ecosystem steadily affect the mass feeding of carriers of natural focal infections.

A Comparison of Small Rodent Assemblages after a 20 Year Interval in the Alps.

Human-induced environmental alterations in the Alps may importantly affect small mammal species, but evidence in this sense is limited. We live-trapped small rodents in the Central-Eastern Italian Alps in three close-by habitat types (rocky scree, alpine grassland, and heath) at 2100 m a.s.l. during summer-fall, in 1997 and 2016. We compared small rodent assemblages through a Redundancy Detrended Analysis (RDA). In both surveys, we detected two specialist species, i.e., the common vole (Microtus arvalis) and the snow vole (Chionomys nivalis), and, unexpectedly, the forest generalist bank vole (Myodes glareolus). In 1997, grassland was mainly occupied by the common vole, while the bank vole and the snow vole were sympatric in the other habitats. In 2016, the snow vole was detected only in the scree, while other species did not show distribution changes. We discuss a series of hypotheses that might have driven the differences observed across decades, among which is a species-specific response to abiotic and biotic environmental alterations, with the alpine habitat specialist moving out of sub-optimal habitats. We encourage further research on this topic, e.g., via long-term longitudinal studies.

The impact of wildlife and environmental factors on hantavirus infection in the host and its translation into human risk.

Identifying factors that drive infection dynamics in reservoir host populations is essential in understanding human risk from wildlife-originated zoonoses. We studied zoonotic Puumala orthohantavirus (PUUV) in the host, the bank vole (Myodes glareolus), populations in relation to the host population, rodent and predator community and environment-related factors and whether these processes are translated into human infection incidence. We used 5-year rodent trapping and bank vole PUUV serology data collected from 30 sites located in 24 municipalities in Finland. We found that PUUV seroprevalence in the host was negatively associated with the abundance of red foxes, but this process did not translate into human disease incidence, which showed no association with PUUV seroprevalence. The abundance of weasels, the proportion of juvenile bank voles in the host populations and rodent species diversity were negatively associated with the abundance index of PUUV positive bank voles, which, in turn, showed a positive association with human disease incidence. Our results suggest certain predators, a high proportion of young bank vole individuals, and a diverse rodent community, may reduce PUUV risk for humans through their negative impacts on the abundance of infected bank voles.

Co-infections mask pathogen-specific associations with the gut microbiota in wild voles.

Research Highlight: Brila, I., Lavirinienko, A., Tukalenko, E., Kallio, E. R., Mappes, T. & Watts, P. C. (2022). Idiosyncratic effects of coinfection on the association between systemic pathogens and the gut microbiota of a wild rodent, the bank vole (Myodes glareolus). Journal of Animal Ecology, https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.13869. Interactions between pathogens and host-associated microbial communities can influence host fitness, disease progression and pathogen emergence. The vast majority of studies characterize interactions between single pathogens and bacterial commensals, yet co-infections with multiple pathogens are the norm in nature. In their paper on pathogen-microbiome interactions, Brila et al. (2022) examine how co-infections with four systemic pathogens associate with the gut microbiota in wild bank voles. Building on a series of tests, the authors show that excluding co-infection information from statistical models masks pathogen-specific patterns and confounds interpretations. This paper advances on previous studies by generating surveillance data on a phylogenetically diverse suite of vole pathogens to address the question as to whether pathogens exhibit unique or universal associations with gut commensals. They report that even bacterial pathogens with similar transmission ecology have divergent associations with gut microbes, and highlight that a mechanistic understanding of host-pathogen interactions is necessary for decoding the diverse consequences for gut microbial communities.