Eimeria-parasites are associated with a lowered mother's and offspring's body condition in island and mainland populations of the bank vole

Parasitology ◽  
2006 ◽  
Vol 134 (1) ◽  
pp. 23-31 ◽  
Author(s):  
H. HAKKARAINEN ◽  
E. HUHTA ◽  
E. KOSKELA ◽  
T. MAPPES ◽  
T. SOVERI ◽  
...  

This study, based on correlative data, tests the hypothesis that infections withEimeriaspp. parasites exert a significant loss of fitness of bank voles (Clethrionomys glareolus) reflected in lower reproductive success and survival, declining host population densities and are associated positively with population size. The study was conducted in 20 mainland and 27 island populations in central Finland during May–September in 1999. Faecal samples showed that 28% of 767 individuals were infected withEimeriaspp. The presence ofEimeriaparasites was higher in dense mainland populations than in sparsely populated islands. Eimerian infections increased during the course of the breeding season, probably as a result of the high infection rate of young individuals. Accordingly, the body masses of bank voles were negatively related to the presence ofEimeriaspp. Reproductive output, as measured by the breeding probability of females and litter size, was not associated with the presence of eimerian infection. Interestingly, the body condition of the infected mothers appeared to be low. Moreover, mother's body condition was the single most important variable studied that showed a positive correlation to pup's body condition at birth. On small islands ([les ]3·2 ha) that were comprehensively trapped, the mean number ofEimeriaspp. in the bank vole population was negatively related to density changes of the bank vole population during the study. Our data are consistent with the idea that infection with coccidian parasites may be one of the factors responsible for declining host populations in small, isolated populations.

1980 ◽  
Vol 58 (8) ◽  
pp. 1458-1461
Author(s):  
Torgny O. Gustafsson ◽  
C. Bertil Andersson

The relative roles of mating and the ovary in the initiating of adrenal growth in pregnant bank voles, Clethrionomys glareolus, were studied. In one experiment females were ovariectomized shortly after mating; 4 days later they had significantly heavier adrenals than unmated, ovariectomized controls. In another experiment females were ovariectomized and brought into oestrus by oestradiol- 17β injections. Half of the females were mated and after 4 days their adrenals were significantly larger than those of unmated controls. We conclude that the increase in adrenal weight during pregnancy in bank voles is triggered directly by mating, without involvement of ovarian hormones. The mechanism is suggested to be a neuroendocrine reflex, acting via the hypothalamus and the pituitary. The mechanism may be the same as that involved in the induced ovulation in this species.


2001 ◽  
Vol 79 (10) ◽  
pp. 1743-1753 ◽  
Author(s):  
Jana A Eccard ◽  
Hannu Ylönen

We studied factors causing variation in the initiation of reproduction after winter in the bank vole (Clethrionomys glareolus), an iteroparous seasonal breeder, by offering different winter food supplements and monitoring local density variation. We used either sunflower seeds or barley to supplement the diet of populations of bank voles in grassland enclosures. In a parallel experiment we used spruce seeds, a natural winter food, to supplement the diet of bank vole populations in unfenced spruce forest. Survival, maturation, and breeding were monitored by livetrapping. Population density decreased during winter in grassland enclosures and remained constant in the forest, with no difference between food treatments. Breeding was initiated earlier in the grassland enclosures than in the forest, probably because of the supplemental food supply in both seed treatments and social and environmental stability in enclosures. Within both experiments, we found no differences in timing of parturition between food treatments. Inter actions of food treatment with density of females influenced the time of initiation of breeding in both experiments. At low densities, breeding started up to 1 month earlier than the population average. At high densities, a proportion of females did not breed during spring. Massive food supplements advanced the initiation of breeding, but among animals with similar food supplies, local population density seemed to have stronger regulatory effects. Local density variations may therefore create asynchronous breeding patterns within populations under similar wintering conditions.


1982 ◽  
Vol 60 (3) ◽  
pp. 387-391 ◽  
Author(s):  
Lilian M. Westlin ◽  
Erik Nyholm

The start of the breeding season of overwintered female bank voles, Clethrionomys glareolus, and also the start of breeding in young of the year, was characterized by a general occurrence of sterile ovulations. Similarly, in laboratory experiments, 23 out of 42 young virgin females failed to become pregnant after the first mating, and often mated several times before becoming pregnant. The experiments indicated that the sterile ovulations were attributed to temporary sterility of the females during maturation either at adolescence or at the beginning of the new breeding season, and not a result of (1) initial ovulations of the season being spontaneous, (2) male sterility, or (3) male-induced pregnancy blockage.


1984 ◽  
Vol 93 (1) ◽  
pp. 139-146 ◽  
Author(s):  
T. Traavik ◽  
Ann-Inger Sommer ◽  
R. Mehl ◽  
B. P. Berdal ◽  
K. Stavem ◽  
...  

SUMMARYNephropathia epidemica (NE) antigen was detected by IFAT (indirect fluorescent antibody technique) in the lungs of 14 of 97 bank voles (Clethrionomys glareolus) collected in three endemic areas. The distribution of antigen positive voles within an endemic location was scattered. Antibodies to Korean hemorrhagic fever (KHF) virus antigens were detected by IFAT in 12 of 14 NE antigen positive bank voles and in 15 of 83 that were antigen negative. NE antigen positive voles exhibited higher antibody titres. Antibodies to KHF were demonstrated in sera from C. rutilus and C. rufocanus collected more than 200 km north of the distribution area for C. glareolus. It appears likely that these vole species can serve as virus vectors for NE cases occurring north of the bank vole area. NE antibodies cross-reacting with KHF virus seem to diminish with time after infection in some NE patients, while for others such cross-reacting antibodies were detected up to 12 years after the disease. Antibodies to KHF were detected in eight of 106 healthy forestry workers with no clinical history of NE. No serological cross-reactions were detected between NE/KHF antigens and representative Bunyaviridae present in Norway. NE/KHF-like viruses appear widespread in Norway, both within and outside of the distribution area of the bank vole.


2002 ◽  
Vol 80 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Pernilla Jonsson ◽  
Jep Agrell ◽  
Esa Koskela ◽  
Tapio Mappes

Reproductive success of territorial female mammals depends partly on their capability to defend their young from conspecific intruders. However, how this is related to the characteristics of females and their litter sizes is largely unknown. The defence activity of 25 female bank voles (Clethrionomys glareolus) in relation to the number of offspring was studied in a behavioural arena by manipulating litter sizes (–2 pups or +2 pups). Infanticidal male bank voles were used as intruders–predators. Moreover, the weaning success (weaned at least one offspring or none) of 15 pairs of neighbouring females was investigated in a large indoor runway system. In each pair of females, the litter size of one female was reduced (–2 pups) and the litter size of the other enlarged (+2 pups). Defence activity of females increased with the number of offspring and the mother's size. However, weaning success of neighbours was related only to their body mass, and litter-size manipulation did not affect weaning success. Present results indicate that, although bank vole females increase their defence intensity with an increase in the number of pups, the weaning success of neighbouring females may be primarily determined by their size and dominance rank.


1998 ◽  
Vol 76 (7) ◽  
pp. 1329-1334 ◽  
Author(s):  
A Fredric Karlsson ◽  
Eugene R Potapov

Minimum distance moved (MDM) and home-range sizes were studied in overwintering bank voles (Clethrionomys glareolus) during March and April in 1985, 1986, and 1996 near Uppsala, Sweden. In 1985 and 1986, the average snow depth was 50 and 35 cm in March and 7 and 18 cm in April, respectively. In 1996 the snow depth was only 16 cm in March and 2 cm in April. Bank voles were found to have winter nests at exactly the same grid coordinates in 1985, 1986, and 1996. Among females there was a high degree of consistency in home-range sizes, both between months and between years. Daily MDM of females was shorter in March 1996 than in 1985 and 1986, while no significant difference occurred during April. Males' home-range sizes, on the other hand, increased significantly from March to April in all 3 years, i.e., at the onset of the mating period. There was no significant difference in males' home-range sizes in March across years, but in April, home ranges were significantly larger 1985 and 1986 than in 1996. Males' average home-range sizes in April showed a positive correlation with snow depth. MDM of males in both March and April was also significantly higher during the snowy years of 1985 and 1986 than in 1996, when there was much less snow. These observations suggest that adequate snow cover is a favourable factor, allowing the males to expand their home ranges, while lack of snow or a thin, patchy snow cover prevents them from travelling longer distances during the mating period and consequently from visiting a large number of potential mates. These differences in the behaviour of male bank voles between snow-rich and snow-poor years may offer a partial explanation of the hypothetical connection between the less severe winter conditions during the past decade and the decline in population density and cyclicity in boreal bank vole populations.


2008 ◽  
Vol 275 (1638) ◽  
pp. 1095-1100 ◽  
Author(s):  
Ines Klemme ◽  
Hannu Ylönen ◽  
Jana Anja Eccard

Polyandry, i.e. mating with multiple males within one reproductive event, is a common female mating strategy but its adaptive function is often unclear. We tested whether polyandrous females gain genetic benefits by comparing fitness traits of monandrous (mated twice with a single male) and polyandrous (mated twice with two different males) female bank voles Clethrionomys glareolus . We raised the offspring in the laboratory until adulthood and measured their body size, before releasing them to outdoor enclosures to overwinter. At the onset of the breeding season in the following spring, we found that offspring of polyandrous females performed significantly better at reproduction than those of monandrous females. This was mainly due to sons of polyandrous females producing significantly more offspring than those of monandrous females. No significant differences were found for offspring body mass or winter survival between the two treatments. Our results appear to provide evidence that bank vole females gain long-term benefits from polyandry.


Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 856
Author(s):  
Linas Balčiauskas ◽  
Laima Balčiauskienė

Scarcely investigated in terms of small mammals, kitchen gardens and homesteads form a subset of environments. Using results of snap trapping, we present the first data on small mammal species diversity, gender and age structure, relative abundance, body fitness, and reproduction parameters in these commensal habitats (kitchen gardens, homestead gardens, houses, and outbuildings). We expected that (i) house mice should be the dominant species in buildings, while striped field mice should be dominant in gardens, (ii) body condition should be the highest in buildings, (iii) body condition should increase in the autumn, irrespective of the habitat, and (iv) breeding failures in the form of disrupted pregnancies should be observed. Not all of the predictions were confirmed. From the seven recorded species, gardens and outbuildings were dominated by yellow-necked mice, while bank voles dominated in buildings where food was available. The number of recorded species and diversity index increased during the autumn months. The body condition was highest in rodents that were trapped in gardens. It decreased towards winter, with the exception of the striped field mouse. Breeding disturbances were recorded in all of the most numerous species, comprising 16.7–100% of all observed pregnancies.


Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1258
Author(s):  
Julia Schneider ◽  
Bernd Hoffmann ◽  
Cristina Fevola ◽  
Marie Luisa Schmidt ◽  
Christian Imholt ◽  
...  

The development of new diagnostic methods resulted in the discovery of novel hepaciviruses in wild populations of the bank vole (Myodes glareolus, syn. Clethrionomys glareolus). The naturally infected voles demonstrate signs of hepatitis similar to those induced by hepatitis C virus (HCV) in humans. The aim of the present research was to investigate the geographical distribution of bank vole-associated hepaciviruses (BvHVs) and their genetic diversity in Europe. Real-time reverse transcription polymerase chain reaction (RT-qPCR) screening revealed BvHV RNA in 442 out of 1838 (24.0%) bank voles from nine European countries and in one of seven northern red-backed voles (Myodes rutilus, syn. Clethrionomys rutilus). BvHV RNA was not found in any other small mammal species (n = 23) tested here. Phylogenetic and isolation-by-distance analyses confirmed the occurrence of both BvHV species (Hepacivirus F and Hepacivirus J) and their sympatric occurrence at several trapping sites in two countries. The broad geographical distribution of BvHVs across Europe was associated with their presence in bank voles of different evolutionary lineages. The extensive geographical distribution and high levels of genetic diversity of BvHVs, as well as the high population fluctuations of bank voles and occasional commensalism in some parts of Europe warrant future studies on the zoonotic potential of BvHVs.


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