Biological activity of soils in the settlements of southern (Microtus rossiaemeridionalis) and bank (Clethrionomys glareolus) voles

The effect of southern (Microtus rossiaemeridionalis) and bank (Clethrionomys glareolus) voles on the biological activity of soddy-podzolic soil and agrozem has been studied. To estimate this effect, the activity of nitrogen and carbon transformation in the soil taken from the paths and different chambers of the holes of these rodents, as well as from the control plots where there were no voles, has been determined. The contents of organic carbon and nitrogen in the soil have been found. The parameters of functional diversity of the microbial community of soil have been studied. It has been noted that the effect of voles on the biological activity of the above soils manifested itself in increased intensity of aerobic and anaerobic destruction of organic matter and changes in the parameters of functional diversity of the microbial community of soils.     

Androgen-dependent proteins in the urine of bank voles (Clethrionomys glareolus)

The concentration of proteins in the urine of adult bank vole males was higher than that in urine of immature males and females. After separation of the urine by polyacrylamide gel electrophoresis in the presence of SDS, the principal urinary protein had a slightly lower mobility than cytochrome C. Urine from females or castrated males contained only trace amounts of this protein. Injection of testosterone into castrated males increased this protein band. We suggest that bank vole males, like those of rats and mice, synthesize and release in their urine an androgen-dependent protein fraction.     

Tooth wear patterns in voles (Microtus agrestis and Clethrionomys glareolus) and efficiency of dentition in preparing food for digestion

Voles (Microtinae) are among the smallest of mammals which feed extensively on plant leaf material. They achieve higher digestive efficiencies than large ungulates, and this study considers the role that dentition may play in grinding food into small particles, so assisting efficient digestion. Bank ( Clethrionomys glareolus) and field voles ( Microtus agrestis) were found to chew their food into far smaller particles than ungulates, field voles producing smaller particle sizes than bank voles. Scanning electron micrographs showed differences in tooth wear patterns between species, and in bank voles a change in diet led to changes in tooth wear and to changes in the efficiency with which food was processed. Field voles have a pore structure on the occlusal surface of the molar teeth which could play an important role because when the teeth act antagonistically these pores could grate fragments of plant leaves into very small particles and hence enable the animals to achieve high digestive efficiencies.     

Seasonal effects on sexual maturation of male bank voles (Clethrionomys glareolus)

The weights of the testes and accessory glands, and the degree of morphological and functional development of the seminiferous tubules, were used as indicators of sexual maturation in male bank voles. Males reared under constant laboratory conditions showed a significant relationship between the seasons and sexual maturation. Young males reached maturity most rapidly in the reproduction season (mid-April to mid-October), while adult males matured earlier, in the spring season (mid-January to mid-April). The influence of season on animals reared in outdoor cages was much more pronounced. One of the important factors was the photoperiod: animals reared from 3 to 12 weeks of age in a short photoperiod (8L:16D) matured less rapidly than did those reared in 16L:8D.     

Spatial memory in bank voles (Clethrionomys glareolus Schreb) assessed in the cue-controlled open field with the place of refuge

The capacity of bank voles (Clethrionomys glareolus Schreb) for rapid spatial learning was assessed in cue-controlled open field using their species-specific habits (high fear). Animals were tested in open field after 3 days of pretraining. During testing, novel stimuli (black-and-white geometric figures arranged in symmetric or asymmetric modes for different vole groups) were attached to a curtain surrounding the open field, and a shelter (a familiar box from the home cage) was introduced into the field. Testing consisted of four 10-min trials, the last (probe) trial was performed without the shelter. Time spent in different fielld areas was recorded. The voles remembered previous location of the shelter and preferred to visit this area. It was possible only in the condition with asymmetric arrangement of visual stimuli when animals could use them for navigation. The findings conclude that bank vole have a good capacity for rapid spatial learning.     

Indication of a genetic basis of stereotypies in laboratory-bred bank voles (Clethrionomys glareolus)

The development of stereotypies was studied in two successive laboratory-bred generations of bank voles representing F1 (n=248) and F2 (n=270) of an originally wild caught stock. It was shown that the propensity to develop stereotypies under barren housing conditions strongly relates to the same propensity of the parents. Stereotypies were approximately seven times more frequent in the offspring of stereotyping parents than in the offspring of permanent non-stereotypers. This held true even when only one of the parents was stereotyper. The paternal and maternal contributions to stereotypies in the offspring appeared to be equal. Males showing stereotypies but prevented from any physical contact with the offspring were as potent as stereotyping females in producing stereotyping offspring. Moreover, the specific type of stereotypy appearing in the offspring after isolation was very much related to the type of stereotypy developed in the mothers. We found no support for the possible importance of social facilitation from littermates, in that the development of stereotypies was independent of the length of time the voles were kept socially with littermates before isolation. We suggest that the possible genetic basis of individual differences in the propensity to develop stereotypies in captivity may result from differences in genetic predispositions and their interactions with discrete frustrating stimuli early in life and/or to genetically different predispositions to cope with frustrating experiences later in life.     

Maturity, castration and behaviour of male Bank voles, Clethrionomys glareolus (Mammalia)

This paper discusses the relationship between aggressive behaviour and sexual maturity, prepubertal castration and wounding in male Bank voles, Clethrionomys glareolus. In neutral arena tests in the laboratory, sexually mature males exhibited more aggressive components of behaviour than immature males or than adult males that had been castrated prepubertally. Mature males also exhibited fewer amicable components than the immature or castrated males. During several months residence in large outdoor enclosures, mature males consistently had more fresh skin wounds (inflicted by other voles) than did either immature or castrated males. The relevance of these results to the population ecology of Bank voles is discussed.     

Hantavirus antibody occurrence in bank voles (Clethrionomys glareolus) during a vole population cycle

Puumala virus, genus Hantavirus, is the etiologic agent of nephropathia epidemica, a mild form of hemorrhagic fever with renal syndrome. The bank vole (Clethrionomys glareolus) is the natural reservoir species of this hantavirus. We initiated sampling of bank voles at sites of recently identified human nephropathia epidemica cases and paired control sites in the fall of 1995 in coastal areas of northern Sweden. Sites were trapped annually in spring and fall until 1999. Prevalence of antibody to Puumala virus was similar among local bank vole populations in the two types of sites over time. During peak years, however, the absolute number of bank voles was higher in case sites than control sites. Consequently, the likelihood of Puumala virus exposure was increased at case sites during population highs. This would imply that the risk of Puumala virus exposure to conspecifics and humans is habitat and site dependent with a temporal component.     

Detection of the larva of Taenia multilocularis in 2 voles (Microtus arvalis and Clethrionomys glareolus) in a focus of alveolar echinococcosis in the Massif Central (France)

Small wild rodents were collected and examined during 1983-1984 to investigate parasite-host relationships of Echinococcus multilocularis in one habitat suitable for red foxes of Auvergne (France). The natural infestation of the liver of two different voles, Microtus arvalis and Clethrionomys glareolus, by the larval stage of the cestode is recorded for the first time. In the both cases, the larvae were fully developed and numerous protoscolices were present with some calcareous corpuscules; the expansion of the larvae involved several hepatic lobes in Microtus and was restricted to a single lobe in Clethrionomys. Epidemiological consequences of the receptivity of the two hosts are not yet investigated in the field. However several species of voles inhabiting the same endemic area and which are receptive to the larval stage of alveolar echinococcosis should be a favourable factor of durability for the cestodiasis of the foxes; so the parasite is able of surviving the cyclic and considerable but not simultaneous fluctuations of the three populations of voles which are locally implicated in the zoonosis: M. arvalis, C. glareolus and Arvicola terrestris, by changing from one species to the others.     

Breeding of captive bank voles (Clethrionomys glareolus) related to dynamics of source populations

Proportionately fewer female bank voles from cyclic or dense populations bred than did females from sparse or non-cyclic populations when brought into a laboratory and kept as monogamous pairs for at least 1 year. Similarly, fewer litters were produced by females from cyclic or dense populations. Breeding frequency and litter production did not differ in the second laboratory generation. Large variance in litter numbers indicated further changes in reproduction in response to the laboratory environment. Certain differences between origins still persisted after long-term laboratory breeding. The regional variations between field-born animals are most parsimoniously explained by differences in sensitivity to density.     

Influence of age and artificial vaginal stimulation on fertility in female bank voles (Clethrionomys glareolus)

Female bank voles mated when 30-50 days old showed only 20-25% fertility at the first mating, but fertility increased to about 80% in animals greater than 100 days of age at the first mating. Young females subjected to artificial cervical stimulation after the completion of a normal mating showed a much higher fertility than normally mated controls (76 compared with 29%). The reason for the low fertility therefore appears to be that young females require more stimulation to activate the corpora lutea than is normally received at a mating.