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Fertility control is often heralded as a humane and effective technique for management of overabundant wildlife, including rodents. The intention is to reduce the use of lethal and inhumane methods, increase farm productivity and food security as well as reduce disease transmission, particularly of zoonoses. We developed a framework to guide researchers and stakeholders planning to assess the effectiveness of a potential contraceptive agent for a particular species. Our guidelines describe the overarching research questions which must be sequentially addressed to ensure adequate data are collected so that a contraceptive can be registered for use in broad‐scale rodent management. The framework indicates that studies should be undertaken iteratively and, at times, in parallel, with initial research being conducted on (1) laboratory‐based captive assessments of contraceptive effects in individuals; (2) simulation of contraceptive delivery using bait markers and/or surgical sterilization of different proportions of a field‐based or enclosure population to determine how population dynamics are affected; (3) development of mathematical models which predict the outcomes of different fertility control scenarios; and (4) implementation of large‐scale, replicated trials to validate contraceptive efficacy under various management‐scale field situations. In some circumstances, fertility control may be most effective when integrated with other methods (e.g. some culling). Assessment of non‐target effects, direct and indirect, and the environmental fate of the contraceptive must also be determined. Developing fertility control for a species is a resource‐intensive commitment but will likely be less costly than the ongoing environmental and economic impacts by rodents and rodenticides in many contexts. [ABSTRACT FROM AUTHOR]

Human Puumala virus (PUUV) infections in Germany fluctuate multi-annually, following fluctuations of the bank vole population size. We applied a transformation to the annual incidence values and established a heuristic method to develop a straightforward robust model for the binary human infection risk at the district level. The classification model was powered by a machine-learning algorithm and achieved 85% sensitivity and 71% precision, despite using only three weather parameters from the previous years as inputs, namely the soil temperature in April of two years before and in September of the previous year, and the sunshine duration in September of two years before. Moreover, we introduced the PUUV Outbreak Index that quantifies the spatial synchrony of local PUUV-outbreaks, and applied it to the seven reported outbreaks in the period 2006–2021. Finally, we used the classification model to estimate the PUUV Outbreak Index, achieving 20% maximum uncertainty. [ABSTRACT FROM AUTHOR]

Management of overabundant rodents at a landscape scale is complex but often required to sustainably reduce rodent abundance below damage thresholds. Current conventional techniques such as poisoning are not species specific, with some approaches becoming increasingly unacceptable to the general public. Fertility control, first proposed for vertebrate pest management over 5 decades ago, has gained public acceptance because it is perceived as a potentially more species‐specific and humane approach compared with many lethal methods. An ideal fertility control agent needs to induce infertility across one or more breeding seasons, be easily delivered to an appropriate proportion of the population, be species specific with minimal side‐effects (behavioral or social structure changes), and be environmentally benign and cost effective. To date, effective fertility control of rodents has not been demonstrated at landscape scales and very few products have achieved registration. Reproductive targets for fertility control include disrupting the hormonal feedback associated with the hypothalamic‐pituitary‐gonadal axis, gonad function, fertilization, and/or early implantation. We review progress on the oral delivery of various agents for which laboratory studies have demonstrated efficacy in females and/or males and synthesize progress with the development and/or use of synthetic steroids, plant extracts, ovarian specific peptides, and immunocontraceptive vaccines. There are promising results for field application of synthetic steroids (levonorgestrel, quinestrol), chemosterilants (4‐vinylcyclohexene diepoxide), and some plant extracts (triptolide). For most fertility control agents, more research is essential to enable their efficient and cost‐effective delivery such that rodent impacts at a population level are mitigated and food security is improved. [ABSTRACT FROM AUTHOR]

AbstractRodent pests pose significant impacts to agricultural systems and public health globally. Effective strategies for sustainable management while minimizing environmental impacts are crucial. To address the multifaceted nature of rodent impacts, well-coordinated initiatives are necessary to support control strategies, raise awareness among authorities, and inform the public. There is increasing global evidence of Working Groups delivering successful management of a range of natural resource management issues. We outline three case study working groups to tackle rodent pests: (1) National Mouse Group in Australia to manage mouse plague impacts, (2) Working Group Common Vole Management in Germany to manage common vole impacts, and (3) FREDON network for vole management in France. Each working group evolved independently, but all have remarkably similar structures, including monitoring, modelling/forecasting, regular stakeholder meetings (including producers, researchers, government agency staff and others), developing advice for management and identifying research priorities. The success of these working groups was related to: (1) broad stakeholder engagement (particularly farmers/producers), (2) dedicated funding to conduct direct research to inform control strategies, (3) maintained momentum through all phases of rodent population cycles, and (4) benefit for all stakeholders. As rodenticides are increasingly restricted, such working groups will become more important in the future, because stakeholder engagement is necessary to develop rodent management “toolboxes”. [ABSTRACT FROM AUTHOR]

Common voles (Microtus arvalis) are widespread in the European agricultural landscape from central Spain to central Russia. During population outbreaks, significant damage to a variety of crops is caused and the risk of pathogen transmission from voles to people increases. In 2019, increasing or unusually high common vole densities have been reported from several European countries. This is highly important in terms of food production and public health. Therefore, authorities, extension services and farmers need to be aware of the rapid and widespread increase in common voles and take appropriate measures as soon as possible. Management options include chemical and non-chemical methods. However, the latter are suitable only for small and valuable crops and it is recommended to increase efforts to predict common voles outbreaks and to develop and field test new and optimized management tools. [ABSTRACT FROM AUTHOR]

The fluctuation of human infections by the Puumala orthohantavirus (PUUV) in Germany has been linked to weather and phenology parameters that drive the population growth of its host species. We quantified the annual PUUV-outbreaks at the district level by binarizing the reported infections in the period 2006–2021. With these labels we trained a model based on a support vector machine classifier for predicting local outbreaks and incidence well in advance. The feature selection for the optimal model was performed by a heuristic method and identified five monthly weather variables from the previous two years plus the beech flowering intensity of the previous year. The predictive power of the optimal model was assessed by a leave-one-out cross-validation in 16 years that led to an 82.8% accuracy for the outbreak and a 0.457 coefficient of determination for the incidence. Prediction risk maps for the entire endemic area in Germany will be annually available on a freely-accessible permanent online platform of the German Environment Agency. The model correctly identified 2022 as a year with low outbreak risk, whereas its prediction for large-scale high outbreak risk in 2023 was not confirmed. [ABSTRACT FROM AUTHOR]

Anticoagulant rodenticides (ARs) are commonly used to control rodent infestations for biocidal and plant protection purposes. This can lead to AR exposure of non-target small mammals and their predators, which is known from several regions of the world. However, drivers of exposure variation are usually not known. To identify environmental drivers of AR exposure in non-targets we analyzed 331 liver samples of red foxes (Vulpes vulpes) for residues of eight ARs and used local parameters (percentage of urban area and livestock density) to test for associations to residue occurrence. 59.8% of samples collected across Germany contained at least one rodenticide, in 20.2% of cases at levels at which biological effects are suspected. Second generation anticoagulants (mainly brodifacoum and bromadiolone) occurred more often than first generation anticoagulants. Local livestock density and the percentage of urban area were good indicators for AR residue occurrence. There was a positive association between pooled ARs and brodifacoum occurrence with livestock density as well as of pooled ARs, brodifacoum and difenacoum occurrence with the percentage of urban area on administrative district level. Pig holding drove associations of livestock density to AR residue occurrence in foxes. Therefore, risk mitigation strategies should focus on areas of high pig density and on highly urbanized areas to minimize non-target risk. [ABSTRACT FROM AUTHOR]

Some small mammal populations require human interference to conserve rare or threatened species or to minimize adverse effects in plant production. Without a thorough understanding about how small rodents behave in their environment and consideration of how they react to management efforts, management will not be optimal. Social behavior, spatial and temporal activity patterns, predator avoidance and other behavioral responses can affect pest rodent management. Some of these behavioral patterns and their causes have been well studied. However, their impact on pest rodent management, especially for novel management approaches, is not always clear. Habitat manipulation occurs necessarily through land use and intentionally to reduce shelter and food availability and to increase predation pressure on rodents. Rodents often respond to decreased vegetation height with reduced movements and increased risk sensitivity in their feeding behavior. This seems to result mainly from an elevated perceived predation risk. Behavioral responses may lessen the efficacy of the management because the desired effects of predators might be mediated. It remains largely unknown to what extent such responses can compensate at the population level for the expected consequences of habitat manipulation and how population size and crop damage are affected. It is advantageous to understand how target and non-target species react to habitat manipulation to maximize the management effects by appropriate techniques, timing and spatial scale without causing unwanted effects at the system level. [ABSTRACT FROM AUTHOR]

This article reports that rapid recolonization can be a major problem for the management of overabundant populations if the removal techniques are short term. Continuous removal of individuals minimize rapid recolonization, but it could profoundly alter the population's composition and may in fact separate individuals of high quality from individuals of low quality. If residents were removed and immigration occurred quickly, immigrants would be present in the population and create a bias towards individuals of low quality, assuming that immigrants are of low quality. Trap barrier systems (TBS) were introduced to some Southeast Asian countries for rodent management. If a TBS removed mainly dispersers of low quality and left the resident population intact, the quality of residents near a TBS would be similar to rats in areas without a TBS. Researchers selected 6 experimental plots in irrigated rice monoculture. Each plot was adjacent to a main irrigation channel of 6-m width. The fumigation of burrows was thought to yield residents. Rats were fumigated and dug out of their burrows in the centre of 1 quadrant of the semicircle per trapping session in treatment plots and control plots.

Fertility control is used for the management of overabundant species. If sterilized individuals abandon their territories, fertile immigrants may invade and compromise fertility control. In southeast Asia, ricefield rats (Rattus argentiventer) can cause significant pre-harvest damage to lowland irrigated rice fields and may be a prime target for the use of fertility control. However, little is known about the behavioral response of ricefield rats to sterilization. We tested the effects of surgical and hormonal sterilization on movement patterns of female ricefield rats in rice fields in West Java, Indonesia. We found that surgically sterilized rats had the largest home ranges (1.8 &plumn; 0.1 ha), about twice the size of home ranges of hormonally sterilized rats and fertile rats. Hormonally sterilized rats tended to lose their territories--indicated by a high rate of burrow relocation--although hormonally sterilized, surgically sterilized, and fertile rats did not leave the ricefield system. We found no difference in survival rate and preference for refuge habitats between sterilized and fertile rats. Although changes in movement patterns after sterilization occurred, these changes are unlikely to affect the success of fertility control in ricefield rats negatively because sterilized rats remained in the ricefield system throughout the breeding period. [ABSTRACT FROM AUTHOR]

For the sustainable management of small mammals, fertility control may be used in the future. Little is known about what proportions of females need to be sterilized to achieve an impact on population size and what compensatory processes may act on the population level. We tested the impact of surgical sterilization of zero, 25, 50, and 75% of females on the population dynamics and demography of enclosed populations of ricefield rats (Rattus argentiventer) and damage to rice crop. Sterilizing 50% of female founders (6 of 12) decreased population size at the end of the breeding season by about 50%. We used a simulation model, based on the breeding biology of the ricefield rat in the field and in the control enclosures, to generate the expected dynamics of the enclosure populations. The results suggested that compensation occurred in the enclosures where 75% of female founders (9 of 12) had been sterilized. We detected a slight tendency for 50% higher numbers of recent uterine scars in fertile founder females in the 50% and 75% treatments versus 25% treatments and controls (P = 0.198). The primary demographic mechanism for compensation was higher survival of young rats in enclosures where 75% of females were sterilized. However, compensation only partially offset the decrease in population size. We found no conclusive evidence that the reproductive output of F[sub1] generation females was higher when large proportions of female founders were sterilized. Early in the breeding season, the per capita damage to rice plants in populations without sterilized ricefield rats was increased. Our results suggest that the sterilization of >50% of females in ricefield rat populations can reduce rat population growth and rat damage to rice crops. [ABSTRACT FROM AUTHOR]

Management decreases rodent numbers through reduction of vegetation height and cover along fence lines and other refuge habitats. Most farming practices remove vegetation and the short-term impact of mowing, mulching, harvesting and ploughing was studied on common voles (Microtus arvalis). Population dynamics and demographic parameters were estimated by live trapping before, and after farming practices were carried out. A gradient of disturbance according to the reduction of vegetation height, vegetation cover and nest sites is proposed. Estimates of vegetation height and vegetation cover before, and after farming practices fitted the model as well as the population response. It is concluded that only ploughing can suppress common vole populations the other farming practices being inappropriate to control pest rodents. [Copyright &y& Elsevier]

This study aimed to reveal changes in spatial behaviour of common voles (Microtus arvalis) after alteration of their habitat by farming practices. Radio-collared common voles were tracked before and after mulching, mowing, harvesting wheat, and ploughing in the flood plain of the river Unstrut in central Germany. Voles undisturbed by agricultural practices were tracked on a mulchland, an abandoned pasture, and a cattle pasture. There was a large decrease in home-range size after harvesting wheat (96%, P<0.001). Changes after mowing (–74%, P=0.06) were almost significant whereas changes after mulching were not (+14%, P=0.60). On the cattle pasture we found a decrease in home-range size (42%, P=0.03) possibly due to increased spatial activity of cattle in autumn. There was a positive correlation of home-range size and vegetation height for plots with and without farming activity but no correlation with vegetation cover, population density, and breeding. Radio-collared common voles did not show evasive movements and farming practices did not cause a shift of centres of activity. Common voles clearly reacted to sudden changes in vegetation height, which may indicate an immediate response to predation risk. [ABSTRACT FROM AUTHOR]

We studied habitat selection and foraging behaviour of the house mouse (Mus domesticus) related to increasing mouse densities and depleting food resources over the breeding season. The study was conducted during the increase phase of an incipient outbreak of mice in a grain-growing area of southeastern Australia. A 3-year rotation created a mosaic of large paddocks of grain crop, pasture, and fallow. The narrow fence lines between paddocks provide an important stable habitat for the mice. We monitored population densities with live-trapping and habitat preference by measuring giving-up densities (GUD) using artificial food patches. Food patches were established in crop fields, fence lines, and pasture. Avian predation risk was assessed by daily counts of raptors. Before harvest most mice were found in the crop fields. Fewer mice were found along the fence lines and no mice were found in the pasture. After harvest, the number of mice increased along the fence line and in the pasture. Mice started to exploit pasture but only a few trays were visited. As the population densities of mice increased, they inhabited all habitats. Feeding activity in the pasture remained low due to high predation risk. Along fence lines feeding activity increased and mice exploited open and covered patches similarly. We conclude that during high densities mice experience a strong trade-off between food and safety. Vegetation along fence lines offered cover but little food. However, soon after harvest this habitat was favoured by mice. Pasture offered little food and was an extremely risky habitat because of the lack of cover. We suggest that during high densities of mice, habitat use became more opportunistic. Mice took greater risks in all habitats and within each habitat at the microhabitat level. The "Stalingrad effect" is a good descriptor of foraging decisions of mice during the progression of an incipient plague in the cereal-growing regions of southeastern Australia. [ABSTRACT FROM AUTHOR]

We used depletable food patches to determine the effect of microhabitat (mowed versus unmowed adjacent grasslands) and time (day versus night) on the foraging behavior of common voles (Microtus arvalis ). The food remaining after 12-h periods (giving-up density, GUD) measured the vole's habitat selection under predation risk. In accord with several other rodent species and the effects of avian predators, voles had significantly lower GUDs in the unmowed than mowed portion of the grassland. GUDs in patches along the border between adjacent habitats were more similar to the risky mowed grassland than the safe unmowed grass. Time interacted strongly with microhabitat. In the mowed grass, voles had significantly higher GUDs at night than day. Whereas in the unmowed grass, GUDs were significantly higher during the day than night. Vole GUDs did not vary with time along the boundary. This suggests that predators are more abundant or effective in the mowed grass at night (owls?), and in the unmowed grass during the day (weasels?). In terms of predation risk, the voles perceived the mowed grass at night as the riskiest and the unmowed grass at night as the safest. Voles may have difficulties assessing resources under high predation risk: GUDs among patches were well equalized in the unmowed microhabitat whereas in the mowed grass only day GUDs did not vary significantly among patches. We linked these results to the vole's day-night-activity and life span. For the 533 voles live-trapped at the study area, the ratio of day versus night captures for each individual served as an activity index and the span between first and last capture measured minimum life span. In accord with higher GUDs at night, very few individuals behaved selectively towards the night, but individual life expectancy increased with temporal opportunism. Microhabitat differences in GUDs reflect short-term strategies of predator avoidance and the trapping data reflect long-term patterns of anti-predator behavior. [ABSTRACT FROM AUTHOR]

Simple Summary: Bait-based fertility control could contribute to rodent pest management. Bait containing 4-vinylcyclohexene diepoxide (VCD) and triptolide (TP), registered as ContraPest®, was delivered to male common voles to assess the effects on reproductive structures and residues in the liver and testes. There were no effects or inconclusive effects for most reproductive parameters considered. However, there was an increase in sperm defects in voles treated for 14/28 days and fewer normal sperm cells in voles treated for 28 days. There were no TP residues in the testes, few and low TP residues and no VCD residues in the liver tissue. Treatments with VCD + TP seemed to have minor effects on male reproductive organs. Some rodent species cause significant damage to agriculture and forestry, and some can transmit pathogens to humans and livestock. The common vole (Microtus arvalis) is widespread in Europe, and its population outbreaks have resulted in massive crop loss. Bait-based fertility control could contribute to rodent pest management. Bait containing 4-vinylcyclohexene diepoxide (VCD) and triptolide (TP), registered as ContraPest®, was delivered to male common voles for 14 or 28 consecutive days. The effects on reproductive structures and residues in the liver and testes were assessed. There was no effect on testis weight, sperm viability, sperm motility and oxidative stress in sperm cells. Results regarding the mitochondrial membrane potential of sperm, DNA fragmentation and progressively motile sperm cells were inconclusive. However, there was an increase in morphological sperm defects in voles treated for 14/28 days and fewer normal sperm cells in voles treated for 28 days. There were no TP residues in the testes, few and low TP residues and no VCD residues in liver tissues, making considerable secondary exposure to non-target species unlikely. Treatments with VCD + TP seemed to have minor effects on the reproductive organs of males. Further studies should evaluate the effect of VCD + TP on females and on the reproductive success of common voles and other pest rodent species. [ABSTRACT FROM AUTHOR]

Simple Summary: Hair tubes provide a non-invasive method for determining the presence and activity of small mammals by evaluating hair left in hair tubes. Data can be converted into activity indices. In this study, a specially adapted program was developed to semi-automatically determine hair density as a proxy of activity. Adhesive tape with hair from a field experiment was processed, scanned, and analyzed by the program to obtain a quantitative measure of hair density. The validation of hair tubes with wildlife cameras in the field showed a moderate-to-strong positive correlation between hair tube data and recorded rodents. The program is simple but effective and does not require a large amount of deep learning data. Due to its reduced complexity, it facilitates error detection and fine-tuning. The use of hair tubes in combination with this program should provide an easy-to-use, non-invasive method to determine small mammal activity. Activity indices are used to determine the presence and activity of small mammals, such as the hair index derived from the use of hair tubes. In contrast to trapping animals, hair tubes are non-invasive and less labor-intensive, and appear to be a suitable alternative in appropriate settings. We developed a method to calculate hair density semi-automatically. In addition, hair tube data were validated with field data using wildlife cameras for the small mammal community in grassland, wheat crops, and hedges to assess how well data from hair tubes match data from wildlife cameras. Adhesive tape with hair from hair tubes was processed and scanned. The resulting images were analyzed using a newly developed computer program that enables background and adhesive tape to be automatically distinguished from hair, providing a quantitative measure of hair density. Based on validation with wildlife cameras, hair tubes seem to be a suitable tool to estimate small mammal activity at the community level in several habitats. There was a moderate-to-strong positive correlation of the hair tube index with the sum of voles and Apodemus individuals (activity index) recorded in grasslands (Spearman's correlation coefficient 0.43), hedges (0.79), and wheat (0.44). The newly developed computer program allows the automatic calculation of hair density, making it easier to assess the activity of small mammals. [ABSTRACT FROM AUTHOR]

Balancing foraging gain and predation risk is a fundamental trade-off in the life of animals. Individual strategies to acquire, process, store and use information to solve cognitive tasks are likely to affect speed and flexibility of learning, and ecologically relevant decisions regarding foraging and predation risk. Theory suggests a functional link between individual variation in cognitive style and behaviour (animal personality) via speed-accuracy and risk-reward trade-offs. We tested whether cognitive style and personality affect risk-reward trade-off decisions posed by foraging and predation risk. We exposed 21 bank voles (Myodes glareolus) that were bold, fast learning and inflexible and 18 voles that were shy, slow learning and flexible to outdoor enclosures with different risk levels at two food patches. We quantified individual food patch exploitation, foraging and vigilance behaviour. Although both types responded to risk, fast animals increasingly exploited both food patches, gaining access to more food and spending less time searching and exercising vigilance. Slow animals progressively avoided high-risk areas, concentrating foraging effort in the low-risk one, and devoting >50% of visit to vigilance. These patterns indicate that individual differences in cognitive style/personality are reflected in foraging and anti-predator decisions that underlie the individual risk-reward bias. [ABSTRACT FROM AUTHOR]

Rodents are important reservoirs for zoonotic pathogens that cause diseases in humans. Biodiversity is hypothesized to be closely related to pathogen prevalence through multiple direct and indirect pathways. For example, the presence of non‐host species can reduce contact rates of the main reservoir host and thus reduce the risk of transmission ("dilution effect"). In addition, an overlap in ecological niches between two species could lead to increased interspecific competition, potentially limiting host densities and reducing density‐dependent pathogen transmission processes. In this study, we investigated the relative impact of population‐level regulation of direct and indirect drivers of the prevalence of Puumala orthohantavirus (PUUV) in bank voles (Clethrionomys glareolus) during years with high abundance. We compiled data on small mammal community composition from four regions in Germany between 2010 and 2013. Structural equation modeling revealed a strong seasonality in PUUV control mechanisms in bank voles. The abundance of shrews tended to have a negative relationship with host abundance, and host abundance positively influenced PUUV seroprevalence, while at the same time increasing the abundance of competing non‐hosts like the wood mouse (Apodemus sylvaticus) and the yellow‐necked field mouse (Apodemus flavicollis) were associated with reduced PUUV seroprevalence in the host. These results indicate that for PUUV in bank voles, dilution is associated with increased interspecific competition. Anthropogenic pressures leading to the decline of Apodemus spp. in a specific habitat could lead to the amplification of mechanisms promoting PUUV transmission within the host populations. [ABSTRACT FROM AUTHOR]

Common voles (Microtus arvalis) can cause severe crop damage in European agriculture and are usually managed with rodenticides. Population dynamics and behavioral studies question rodenticide effectiveness, and an ecologically based management is needed. A useful addition to such a toolbox could be repelling odor barriers along field margins minimizing migration of voles to crops. We screened 17 plant products and mammalian scents in T-maze trials to test their repelling effects. The most repelling compounds (carrot seed oil (CS), black pepper oil (BP), spruce needle oil (SN), benzaldehyde (BA), BA and BP in double concentration (dc), combinations of BP + BA and BP + CS) were tested further in enclosures. We measured in four populations how often voles crossed enclosure compartments through channels treated with a compound or without a compound. In addition, the amount of rolled oats eaten by voles near treated and untreated channels was compared. In enclosures, voles avoided significantly channels treated with BP (79% more crossings through the control channel) and BP (dc) (42%). Voles consumed significantly more rolled oats near control channels than in the presence of BP + CS (72% more feeding at control), CS (51%), BA (dc) (36%), BP (32%) and BA + BP (28%). This demonstrated for the first time that natural compounds can reduce uptake of a highly attractive food source in common voles under semi-natural conditions. BP + CS was the most successful feeding deterrent and has the potential to be included in an ecologically based management approach. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue, including one by Gerry Wolff on the basic elements of rodent social behavior and another by Avenant on how the species composition of rodents in a South African nature reserve correlates to disturbance and succession.

The article discusses various reports published within the issue, including one about life-history traits, food supply and population dynamics of the white-footed mouse, and another on rodent management.

Second-generation anticoagulant rodenticides potentially build persistent residues in animals and accordingly pose a risk of secondary poisoning. We examined the effect of a low concentration of cholecalciferol in brodifacoum bait on bait consumption by Norway rats (Rattus norvegicus Berkenhout 1769) and on the control success in a laboratory study and in field trials. Additionally, the efficacy of both baits was determined against resistant Y139C rats. Cholecalciferol caused a strong stop-feed effect after two days in the laboratory study. On two field study sites each, bait containing either 25 mg kg−1 brodifacoum or 25 mg kg−1 brodifacoum and 100 mg kg−1 cholecalciferol was applied to treat infestations of Norway rats. Infestations were assessed pre- and post-treatment. Rats were radio-tagged, and carcasses were searched for during the treatment period. DNA of each rat was genotyped to determine the resistance status conferred by the VKORC1 gene. On all farms, control success exceeded 90%. On farms treated with brodifacoum only, the ratio of total bait consumption to pre-treatment census was significantly higher (6.6 and 4.8 times) than on farms treated with the combination (2.7 and 2.9 times). 78.8% of 183 rats were confirmed Y139C resistant. Bait ingestion was reduced by almost fifty per-cent when cholecalciferol was added to the bait with no impact on control success. All treatments resulted in control levels exceeding 90%, despite a high proportion of anticoagulant-resistant rats. When the use of highly toxic compounds is required in resistance management, addition of cholecalciferol to these baits may reduce the transfer of residues to the environment. [ABSTRACT FROM AUTHOR]

Background: Understanding the ecological processes that are involved in the transmission of zoonotic pathogens by small mammals may aid adequate and effective management measures. Few attempts have been made to analyze the ecological aspects that influence pathogen infection in small mammals in livestock production systems. We describe the infection of small mammals with Leptospira spp., Brucella spp., Trichinella spp. and Cysticercus fasciolaris and assess the related intrinsic and extrinsic factors in livestock production systems in central Argentina at the small mammal community, population and individual levels. Methodology/Principal findings: Ten pig farms and eight dairy farms were studied by removal trapping of small mammals from 2008 to 2011. Each farm was sampled seasonally over the course of one year with cage and Sherman live traps. The 505 small mammals captured (14,359 trap-nights) included three introduced murine rodents, four native rodents and two opossums. Leptospira spp., anti-Brucella spp. antibodies and Trichinella spp. were found in the three murine rodents and both opossums. Rattus norvegicus was also infected with C. fasciolaris; Akodon azarae and Oligoryzomys flavescens with Leptospira spp.; anti-Brucella spp. antibodies were found in A. azarae. Two or more pathogens occurred simultaneously on 89% of the farms, and each pathogen was found on at least 50% of the farms. Pathogen infections increased with host abundance. Infection by Leptospira spp. also increased with precipitation and during warm seasons. The occurrence of anti-Brucella spp. antibodies was higher on dairy farms and during the winter and summer. The host abundances limit values, from which farms are expected to be free of the studied pathogens, are reported. Conclusions/Significance: Murine rodents maintain pathogens within farms, whereas other native species are likely dispersing pathogens among farms. Hence, we recommend preventing and controlling murines in farm dwellings and isolating farms from their surroundings to avoid contact with other wild mammals. [ABSTRACT FROM AUTHOR]

Rodents are among the most damaging pests in agriculture worldwide. High-density populations of rodent pests can kill plants or diminish their growth, and reduce both fruit size and the number of seeds. Therefore, rodent pests can lead to considerable crop loss and require management actions to minimize damage. Optimal management of pest rodents is usually based on the combination of methods to reduce damage. Although rodenticides are usually the most commonly deployed approach, they have undesirable side effects. Consequently, more environmentally benign approaches such as repellents or attractants to lure rodents away from fields are gaining traction. The dispersal of a large number of juvenile males at certain times of year has prompted us to focus on male rodents for our experiments. We used laboratory feeding experiments to measure how the odor of plant secondary metabolites (PSMs) affects two pest rodents: common voles ( Microtus arvalis, Pallas) and house mice ( Mus musculus, L.). We tested eighteen different PSMs or combinations thereof with voles. Four PSMs reduced feeding and seven PSMs increased feeding of male common voles. Five of six tested odors were effective as repellents against house mice. However, we assume a species-specific response to volatile PSMs repellents. This study demonstrated that four repellents reduced feeding in both rodent species. Our results contribute to the development of non-lethal management tools for rodent pest species that are potentially more suitable than traps and rodenticides. This approach could be applicable to a variety of crops if effective at field conditions. [ABSTRACT FROM AUTHOR]

Simple Summary: Trapping particular small mammal species is frequently used for scientific purposes but unnecessary bycatch can occur. Live trapping conducted over the last decade in Germany using Ugglan multiple capture traps in grassland, forest and margin habitats revealed about 30% bycatch when target species were common voles (Microtus arvalis) in grassland and common voles and bank voles (Clethrionomys glareolus) in margins and forests. This was more pronounced in spring and along margins. Species mentioned on the early warning list according to the Red List Germany were higher in numbers and proportion in spring and in grassland. The results of the study will help to avoid periods with enhanced presence of bycatch including endangered species (if the purpose of the study allows) or to pay particular attention in certain seasons and habitats when the occurrence of bycatch is most likely. Trapping small mammals is frequently used to study the dynamics, demography, behavior and presence of pathogens. When only particular small mammal species are in the focus of interest, all other species are unnecessary bycatch. We analyzed data from extensive live trapping campaigns conducted over the last decade in Germany, following a consistent standard trapping protocol that resulted in about 18,500 captures of small mammals. Animals were trapped with Ugglan multiple capture traps in grassland, forest and margin habitat. Trap success and the proportion of bycatch were about 30% when target species were common voles (Microtus arvalis) in grassland and common voles and bank voles (Clethrionomys glareolus) in margins and forests. This was more pronounced in spring and along margins. Species mentioned in the early warning list according to the Red List Germany were higher in numbers and proportion in spring and in grassland. The results will help to avoid periods with enhanced presence of bycatch, including endangered species (if the purpose of the study allows) or to pay particular attention in certain seasons and habitats when the occurrence of bycatch is most likely. [ABSTRACT FROM AUTHOR]

Bait markers are indispensable for ecological research but in small mammals, most markers are invasive, expensive and do not enable quantitative analyses of consumption. Ethyl‐iophenoxic acid (Et‐IPA) is a non‐toxic, quantitative bait marker, which has been used for studying bait uptake in several carnivores and ungulates. We developed a bait with Et‐IPA, assessed its palatability to common voles (Microtus arvalis), and determined the dose‐residue‐relation for this important agricultural pest rodent species. Et‐IPA concentrations of 40 to 1280 μg Et‐IPA per g bait were applied to wheat using sunflower oil or polyethylene glycol 300 as potential carriers. In a laboratory study, common voles were offered the bait and blood samples were collected 1, 7, and 14 days after consumption. The samples were analyzed with LC‐ESI‐MS/MS for blood residues of Et‐IPA. Sunflower‐oil was the most suitable bait carrier. Et‐IPA seemed to be palatable to common voles at all test concentrations. Dose‐dependent residues could be detected in blood samples in a dose‐dependent manner and up to 14 days after uptake enabling generation of a calibration curve of the dose‐residue relationship. Et‐IPA was present in common vole blood for at least 14 days, but there was dissipation by 33–37% depending on dose. Et‐IPA meets many criteria for an "ideal" quantitative bait marker for use in future field studies on common voles and possibly other small mammal species. [ABSTRACT FROM AUTHOR]

Presents a correction to the article "Effects of Farming Practices on Spatial Behavior of Common Voles," by Jens Jacob and Nadine Hempel, published in the 2002 issue of the "Journal of Ethology."

Leptospirosis is a neglected zoonotic disease and one of the leading causes of zoonotic morbidity and mortality, particularly in resource-poor settings. Sri Lanka has one of the highest disease burdens worldwide, with occasional endemic leptospirosis outbreaks (2008, 2011). Rodents are considered the main wildlife reservoir, but due to a scarcity of studies it is unclear which particular species contributes to bacterial transmission and reservoir maintenance in this multi-host multi-parasite system. Several rodent species act as agricultural pests both in rice fields and in food storage facilities. To unravel the interactions among the small mammal communities, pathogenic Leptospira spp. and human transmission pathways, we collected animals from smallholder food storage facilities, where contact between humans and small mammals is most likely, and screened kidney tissue samples for Leptospira spp. using PCR. Samples were collected in three climatic zones along a rainfall gradient. Pathogenic Leptospira spp. were detected in small mammal communities in 37 (74%) out of 50 sampled farms and 61 (12%) out of 500 collected individuals were infected. The small mammal community was comprised of Rattus rattus (87.6%), Suncus shrews (8.8%), Bandicota spp. (2.8%) and Mus booduga (0.8%). Three pathogenic Leptospira spp. were identified, L. borgpetersenii (n = 34), L. interrogans (n = 15), and L. kirschneri (n = 1). Suncus shrews were commonly infected (32%), followed by B. indica (23%) and R. rattus (10%). L. borgpetersenii strains similar to strains previously extracted from human clinal samples in Sri Lanka were detected in R. rattus and Suncus shrews. L. interrogans was observed in R. rattus only. A single L. kirschneri infection was found in M. booduga. The presence of human pathogenic Leptospira species in an agricultural pest rodent (R. rattus) and in commensal shrews (Suncus) calls for management of these species in commensal settings. Further investigation of the interplay between pathogen and reservoir population dynamics, overlap in geographic range and the extent of spill-over to humans in and around rural settlements is required to identify optimal management approaches. Author summary: Leptospirosis is a bacterial disease which affects livestock and humans, causing symptoms ranging from asymptomatic to severe morbidity and even mortality in Sri Lanka. The bacterium is known to survive well outside the hosts under favourable conditions such as in a rice-ecosystem. In low-income situations the wellbeing of families can suffer significantly if the principal breadwinner is affected or their livestock turns out sick. In this study rodent host species were sampled in and around smallholder rice storage structures in Sri Lanka with the aim of building knowledge on the wildlife reservoir and potential spill-over events. Leptospira were commonly detected in the black rat and in commensal shrew species. Genetic analysis demonstrated that Leptospira isolates found in these small mammal species were similar to those already isolated from human clinical cases from Sri Lanka. In a biodiversity hotspot such as Sri Lanka, this information can be used to design and implement management strategies which focus on particular host species. [ABSTRACT FROM AUTHOR]

Puumala orthohantavirus (PUUV) is the most important hantavirus species in Europe, causing the majority of human hantavirus disease cases. In central and western Europe, the occurrence of human infections is mainly driven by bank vole population dynamics influenced by beech mast. In Germany, hantavirus epidemic years are observed in 2‐ to 5‐year intervals. Many of the human infections are recorded in summer and early autumn, coinciding with peaks in bank vole populations. Here, we describe a molecular epidemiological investigation in a small company with eight employees of whom five contracted hantavirus infections in late 2017. Standardized interviews with employees were conducted to assess the circumstances under which the disease cluster occurred, how the employees were exposed and which counteractive measures were taken. Initially, two employees were admitted to hospital and serologically diagnosed with hantavirus infection. Subsequently, further investigations were conducted. By means of a self‐administered questionnaire, three additional symptomatic cases could be identified. The hospital patients' sera were investigated and revealed in one patient a partial PUUV L segment sequence, which was identical to PUUV sequences from several bank voles collected in close proximity to company buildings. This investigation highlights the importance of a One Health approach that combines efforts from human and veterinary medicine, ecology and public health to reveal the origin of hantavirus disease clusters. [ABSTRACT FROM AUTHOR]

DNA‐based approaches have greatly improved the applicability of dietary studies aimed at investigating ecological processes. These studies have provided direct insights into, otherwise difficult to measure, interactions between species and trophic levels, food web structure and ecosystem functioning. However, despite these advances, DNA‐based methods have struggled to accurately quantify the whole breadth of diet constituents because of methodological biases, such as amplification bias and digestive processes. The present study is, to our knowledge, the first diet study to use droplet digital PCR to quantify diet constituents. We manipulated the diet of wild‐caught wood mice (Apodemus sylvaticus) by feeding them with a known amount of small vegetable seeds (onion and carrot) and quantified the DNA traces of these diet constituents in faecal samples. The sensitivity of the technique combined with the control on the experimental design allowed mitigation of methodological bias. We were able to accurately determine DNA concentrations of small vegetable seeds in the diet of wood mice. Quantification of target DNA demonstrated significant differences in DNA content when one vs. five seeds were consumed. These differences remained significant when the age, sex and other diet constituents of the mice were altered. Different DNA markers, targeting different parts of the chloroplast, influenced onion DNA detectability. However, all onion and carrot markers showed higher DNA content for higher seed numbers. Overall, the sensitive DNA‐based approach developed in this study allows for minimally invasive quantification of small diet constituents in faeces, which would otherwise be undetectable with traditional methods. [ABSTRACT FROM AUTHOR]

Background: Ixodid ticks are important vectors for zoonotic pathogens, with Ixodes ricinus being the most important in Europe. Rodents are hosts of immature life stages of I. ricinus ticks and are considered main reservoirs for tick-borne pathogens, e.g. Borrelia burgdorferi. The aim of this study was to analyse the prevalence as well as genospecies and sequence type (ST) diversity of Borrelia burgdorferi sensu lato in ticks and small mammals from central Germany and to elaborate on the influence of environmental and/or individual host and vector factors on Borrelia prevalence. Methods: After species identification, 1167 small mammal skin samples and 1094 ticks from vegetation were screened by B. burgdorferi sensu lato real-time polymerase chain reaction, and positive samples were characterized by multilocus sequence typing. Generalized linear (mixed) models were used to estimate how seasonality, small mammal species/tick life stage and habitat affect individual infection status. Results: In total, 10 small mammal species and three tick species, Ixodes ricinus, Ixodes inopinatus (both considered members of the I. ricinus complex) and Dermacentor reticulatus, were investigated. Borrelia DNA was detected in eight host species, i.e. the striped field mouse (Apodemus agrarius), the yellow-necked field mouse (Apodemus flavicollis), the wood mouse (Apodemus sylvaticus), the water vole (Arvicola amphibius), the bank vole (Clethrionomys glareolus), the field vole (Microtus agrestis), the common vole (Microtus arvalis), and the common shrew (Sorex araneus). Two species were Borrelia negative, the greater white-toothed shrew (Crocidura russula) and the pygmy shrew (Sorex minutus). The average prevalence was 6.2%, with two genospecies detected, Borrelia afzelii and Borrelia garinii, and at least three STs that had not been previously reported in small mammals. Borrelia prevalence in small mammals did not differ between seasons. Six genospecies of Borrelia—Borrelia afzelii, Borrelia valaisiana, Borrelia garinii, Borrelia lusitaniae, Borrelia spielmanii, and Borrelia burgdorferi sensu stricto—and 25 STs of Borrelia, of which 12 have not been previously described at all and five have not been previously reported in Germany, were detected in 13% of I. ricinus complex ticks. Prevalence was highest in adult females (25.3%) and lowest in nymphs (11.4%). Prevalence was significantly higher in ticks from grassland (16.8%) compared to forests (11.4%). Conclusions: The high level of small mammal diversity in this region of Germany seems to be reflected in a wide variety of genospecies and STs of B. burgdorferi. [ABSTRACT FROM AUTHOR]

In this study, the ecological effects of culling programs are considered in the context of rodent pest management. Despite the escalation of rodent problems globally, over the past quarter of a century there have not been many new developments in culling programs directed at managing these populations. There is a strong reliance on broad scale use of chemical rodenticides or other lethal methods of control. The ecological consequences of culling programs based on chemical rodenticides and bounty systems are considered. Although rodents cause tremendous economic hardship to people on a continental scale, usually less than 10% of species cause substantial impacts. Indeed, many species of rodent provide important “ecological services” and, given that culling programs rarely distinguish between rodent species, often the non-pest rodents are at grave risk. Rodent control is conducted with little appreciation of what proportion of the population would need to be culled for a significant reduction in economic damage. In Indonesian rice fields, once rodent densities are high then a reduction in yield loss from 30% to 15% would require more than 75% of the population to be culled; a reduction to less than 5% yield loss would require more than a 95% cull. The negative ecological consequences of culling can be better managed if the method is specifically tailored to the species that need to be managed. A greater emphasis on ecologically-based rodent management would assist markedly in reducing the unwanted and unintended effects of culling. [ABSTRACT FROM AUTHOR]

Well-known examples of high-amplitude, large-scale fluctuations of small-mammal populations include vole cycles in the boreal zone of Eurasia, lemming cycles in the high-arctic tundra of Eurasia and North America, snowshoe hare cycles in the boreal zone of North America, and outbreaks of house mice in southeastern Australia. We synthesize the recent knowledge of three key aspects of these animals' population cycles: (1) periodicity, amplitude, and asphaltite synchrony; (2) reproduction and survival; and (3) underlying mechanisms. Survival rather than reproductive rate appears to drive rates of population increase during these fluctuations. Food limitation may stop increases of cyclic vole; lemming, and hare populations, whereas the decline from peak numbers is caused by predation mortality. In house mice, without coevolved predators, outbreaks may he driven by rainfall, food supply, and disease. [ABSTRACT FROM AUTHOR]

Most small rodent populations in the world have fascinating population dynamics. In the northern hemisphere, voles and lemmings tend to show population cycles with regular fluctuations in numbers. In the southern hemisphere, small rodents tend to have large amplitude outbreaks with less regular intervals. In the light of vast research and debate over almost a century, we here discuss the driving forces of these different rodent population dynamics. We highlight ten questions directly related to the various characteristics of relevant populations and ecosystems that still need to be answered. This overview is not intended as a complete list of questions but rather focuses on the most important issues that are essential for understanding the generality of small rodent population dynamics. [ABSTRACT FROM AUTHOR]

Cowpox virus (CPXV), genus Orthopoxvirus, family Poxviridae, is a zoonotic pathogen in Eurasian wild rodents. High seroprevalences have been reported previously for vole and murine species in Europe. In contrast, viral DNA was only rarely detected, and very few reservoir-derived CPXV isolates exist. In this study, CPXV DNA and CPXV-reactive antibodies were monitored in wild small mammals for 5 years in four German federal states. Screening of liver tissues of 3966 animals by CPXV real-time PCR (qPCR) revealed five voles of two species positive for CPXV DNA. Two positive bank voles (Myodes glareolus) and two positive common voles (Microtus arvalis) originated from two plots in Baden-Wuerttemberg. One positive bank vole originated from Mecklenburg-Western Pomerania. None of the small mammals from Thuringia and North Rhine-Westphalia was positive in the qPCR. CPXV antigen-based indirect immunofluorescence assays of 654 highly diluted chest cavity fluid samples detected two bank voles and two common voles from the same sites in Baden-Wuerttemberg to be highly seroreactive. Five animals were CPXV DNA positive, and four other animals were orthopoxvirus seropositive. Our study indicates both a very low prevalence and a patchy occurrence of CPXV in common and bank voles and absence in other rodent and shrew species in Germany. The multiple detection of infected voles at one site in Baden-Wuerttemberg and continued detection in a region of Mecklenburg-Western Pomerania classify these regions as potential endemic foci. [ABSTRACT FROM AUTHOR]

Puumala orthohantavirus (PUUV) causes most human hantavirus disease cases in Europe. PUUV disease outbreaks are usually synchronized Germany‐wide driven by beech mast‐induced irruptions of its host (bank vole, Myodes glareolus). Recent data indicate high vole abundance, high PUUV prevalence and high human incidence in summer 2019 for some regions, but elsewhere values were low to moderate. This significant lack of synchrony among regions in Germany is in contrast to previous studies. Health institutions need to be informed about the heterogeneous distribution of human PUUV infection risk to initiate appropriate actions. [ABSTRACT FROM AUTHOR]

Francisella tularensis is a zoonotic, gram‐negative bacterium that causes tularemia in humans. Depending on its subspecies and the route of transmission, mild to lethal courses have been reported. F. tularensis subsp. holarctica is the only subspecies found in Europe and affects a plenitude of vertebrates including lagomorphs and rodents. Population outbreaks of certain rodent species are likely to be involved in the transmission of this pathogen. This molecular survey aims to evaluate the presence of F. tularensis in small mammals from three Central European countries. Using a real‐time polymerase chain reaction, F. tularensis DNA was detected in common voles (Microtus arvalis) from Switzerland and in field voles (Microtus agrestis) and a bank vole (Myodes glareolus) from Germany, but not in any other small mammal species. All common voles from the Czech Republic were negative for F. tularensis DNA. The prevalence in the three vole species varied between 1.3% and 3.0%. In conclusion, Francisella tularensis DNA was detected in three vole species in two of three countries investigated. The observed low prevalence raises questions on the role of voles for the transmission of Francisella tularensis in Central Europe. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Bisabolol, eugenol and maltol attract common voles in T-maze trials. • Maltol improves trapping success in common voles in enclosed populations. • Maltol could be used to improve the tool box for ecologically-based rodent management after testing under field conditions. Abstract Common voles are serious pests in European agriculture, damaging cereals, rapeseed and other crops and causing substantial losses per outbreak. Not only might the usual approach of applying rodenticides for population management have disadvantages for non-target species, these rodenticides also cannot be used in organic farming. An alternative solution could be an approach related to the concept of ecologically-based rodent management combining environmentally sustainable methods based on knowledge about the target species. Such a method inhibits the dispersal of common voles from field margins to crop habitats via a trap-barrier system. However, little is known about attractants, which could increase the trapping success of common voles. We screened 22 natural substances in T-maze trials. The three most successful substances were further tested during enclosure trials under semi-natural conditions. Bisabolol, eugenol and maltol attracted six of eight voles during the T-maze trials and were mixed into grain pellet bait. Bait containing maltol caught significantly more common voles in enclosures than plain control bait or bait containing bisabolol or eugenol. Of all individuals, 21% chose exclusively baits with maltol. Generalized Linear Mixed Model (GLMM) indicated that every individual would be trapped once in 6 h with this bait type and GLMM predicted that 63% of females and 56% of males would choose this bait over plain control bait. Maltol bait could help either by more efficiently trapping common voles in a trap-barrier system or improving bait acceptance when rodenticides are applied. [ABSTRACT FROM AUTHOR]

Leptospirosis is a worldwide emerging infectious disease caused by zoonotic bacteria of the genus Leptospira. Numerous mammals, including domestic and companion animals, can be infected by Leptospira spp., but rodents and other small mammals are considered the main reservoir. The annual number of recorded human leptospirosis cases in Germany (2001–2016) was 25–166. Field fever outbreaks in strawberry pickers, due to infection with Leptospira kirschneri serovar Grippotyphosa, were reported in 2007 and 2014. To identify the most commonly occurring Leptospira genomospecies, sequence types (STs), and their small mammal host specificity, a monitoring study was performed during 2010–2014 in four federal states of Germany. Initial screening of kidney tissues of 3,950 animals by PCR targeting the lipl32 gene revealed 435 rodents of 6 species and 89 shrews of three species positive for leptospiral DNA. PCR-based analyses resulted in the identification of the genomospecies L. kirschneri (62.7%), Leptospira interrogans (28.3%), and Leptospira borgpetersenii (9.0%), which are represented by four, one, and two STs, respectively. The average Leptospira prevalence was highest (∼30%) in common voles (Microtus arvalis) and field voles (Microtus agrestis). Both species were exclusively infected with L. kirschneri. In contrast, in bank voles (Myodes glareolus) and yellow-necked mice (Apodemus flavicollis), DNA of all three genomospecies was detected, and in common shrews (Sorex araneus) DNA of L. kirschneri and L. borgpetersenii was identified. The association between individual infection status and demographic factors varied between species; infection status was always positively correlated to body weight. In conclusion, the study confirmed a broad geographical distribution of Leptospira in small mammals and suggested an important public health relevance of common and field voles as reservoirs of L. kirschneri. Furthermore, the investigations identified seasonal, habitat-related, as well as individual influences on Leptospira prevalence in small mammals that might impact public health. [ABSTRACT FROM AUTHOR]

Survey techniques available to sample mammals have multiplied during the last decades. They offer new opportunities for sampling and monitoring populations, but before widespread use they need to be validated and calibrated to more traditional approaches. We conducted a quantitative assessment of hair tubes designed to monitor common small mammals by comparing results to live-trapping data. Hair tubes are inexpensive, easy to use, and noninvasive, which offers benefits regarding animal ethics. We considered the shape of the tube, application in field conditions, and validated hair-tube results in 3 different habitats based on experimental and field sampling in 2 countries. Tube size selected species entering into the tubes, with shrews detected in small tubes only and rodents in larger tubes. The number of tubes visited (with hair sample) was proportional to the number of individuals captured in live traps. Overall, tubes performed better than traps, detecting individuals where traps did not, making this technique promising for inventory of rare species. The sampling pattern was robust across wood, grassland, and cultivated field habitats and across seasons, which suggests that the proportion of hair tubes visited is a robust indicator of relative abundance of small mammals. In the context of population studies, hair tubes cannot replace trapping because the identification of species or individuals from hair collected in tubes is difficult and costly. We recommend combining hair tubes with livetrapping for increased efficiency and before species identification based on DNA sampling is applied to large-scale population studies. [ABSTRACT FROM AUTHOR]

Background: Giardiasis is an important gastrointestinal parasitic disease in humans and other mammals caused by the protozoan Giardia duodenalis. This species complex is represented by genetically distinct groups (assemblages A-H) with varying zoonotic potential and host preferences. Wild rodents can harbor potentially zoonotic assemblages A and B, and the rodent-specific assemblage G. Other Giardia spp. found in these animals are Giardia muris and Giardia microti. For the latter, only limited information on genetic typing is available. It has been speculated that wild rodents might represent an important reservoir for parasites causing human giardiasis. The aim of this study was to investigate the occurrence and distribution of Giardia spp. and assemblage types in wild rodents from different study sites in Germany. Results: Screening of 577 wild rodents of the genera Apodemus, Microtus and Myodes, sampled at eleven study sites in Germany, revealed a high overall Giardia prevalence. Giardia species determination at the SSU rDNA gene locus revealed that Apodemus mice, depending on species, were predominantly infected with one of two distinct G. muris sequence types. Giardia microti was the predominant parasite species found in voles of the genera Microtus and Myodes. Only a few animals were positive for potentially zoonotic G. duodenalis. Subtyping at the betagiardin (bg) and glutamine dehydrogenase (gdh) genes strongly supported the existence of different phylogenetic subgroups of G. microti that are preferentially harbored by distinct host species. Conclusions: The present study highlights the preference of G. muris for Apodemus, and G. microti for Microtus and Myodes hosts and argues for a very low prevalence of zoonotic G. duodenalis assemblages in wild rodents in Germany. It also provides evidence that G. muris and G. microti subdivide into several phylogenetically distinguishable subgroups, each of which appears to be preferentially harbored by species of a particular rodent host genus. Finally, the study expands the database of sequences relevant for sequence typing of G. muris and G. microti isolates which will greatly help future analyses of these parasites’ population structure. [ABSTRACT FROM AUTHOR]

Patterns of individual differences in cognition have been studied empirically and systematically in the last decade, but causes and consequences of this variation are still largely unclear. A recent hypothesis suggests that one predictor of individual variation in cognition is personality, and specifically that personality types are linked to cognitive styles through a speed–accuracy trade-off. We tested specific predictions of this hypothesis, measuring individual differences in associative learning speed and flexibility, quantified via reversal learning, of 86 bank voles, Myodes glareolus , along with their activity and boldness. We found that bolder and more active individuals were fast, inflexible and persistent in the associative learning tasks, whereas shyer and less active individuals were slow and flexible. We also found evidence for a speed–accuracy trade-off: correct choices in the cognitive tasks required more time for all individuals compared to incorrect choices, but bolder, more active voles always made their decisions faster than reactive ones. The difference between the time required for a correct and an incorrect choice was most pronounced in initial learning for shyer and less active individuals, but for bolder, more active individuals it was most pronounced in the reversal learning task. We also found differences related to sex and age: females were faster than males to update information or correct incorrect choices and older animals took longer to initiate the test. Our results confirm the hypothesis that individual differences in behaviour are reflected in different ‘cognitive styles’, differentially trading off speed for flexibility and accuracy in cognitive tasks. Moreover, we provide the first evidence for the mechanisms of such a trade-off in a small mammal. [ABSTRACT FROM AUTHOR]

Rodents, including common voles ( Microtus arvalis) and house mice ( Mus musculus) cause immense pre-harvest and post-harvest losses. Therefore, developing methods that mitigate these losses while maintaining their role in ecosystems is a priority. Several plant secondary metabolites (PSM) which significantly reduce food intake of both species under laboratory conditions have been identified. However, before these can be used in rodent pest management, they must be tested under more natural conditions where other food sources are available. In this study, the odors of 4 PSMs were evaluated for their repellent effects in experiments conducted in semi-natural enclosures. Soil treated with PSMs or untreated soil (experimental control) was placed in an underground box containing food (rolled oats). We quantified the number of visits to each box and could demonstrate that all 4 PSMs reduced the number of visits to treatment boxes in both rodent species. For common voles the combination of methyl nonyl ketone + black pepper oil was the most repellent PSM. House mice made fewer visits to all PSM boxes; boxes with the anthraquinone were visited least. Furthermore, house mice consumed less food from boxes containing soil treated with all 4 PSMs. Our results suggest that PSMs are repellent in murid and microtine rodents under semi-field conditions. In addition, the future use of PSM odors for repelling both pest species, especially house mice, seems promising. Further investigations with other PSMs, different concentrations as well as alternative application methods are needed to repel common voles from attractive crops. [ABSTRACT FROM AUTHOR]

Introduction: Leptospirosis is caused by Leptospira spp. and is considered the most widespread zoonotic disease worldwide. It mimics nephropathia epidemica in humans, a disease mainly caused by Puumala hantavirus (PUUV). Small mammals are reservoirs for Leptospira spp. and PUUV. Seewis virus (SWSV) is a shrew-borne hantavirus with unknown pathogenicity. The objective of this study was to estimate the prevalence for Leptospira spp. and the frequency of Leptospira-hantavirus co-infections in small mammals collected at locations with high and low incidences in humans. Materials and Methods: In 2012 and 2013, 736 small mammals belonging to seven species ( Apodemus flavicollis, Microtus agrestis, Microtus arvalis, Myodes glareolus, Sorex araneus, S. coronatus, and S. minutus) were collected at four high incidence sites (H1-H4) and four low (L1-L4) incidence sites for PUUV infection in humans. Kidney-derived DNA samples were tested for Leptospira spp. by real-time PCR targeting the lipl 32 gene and further analyzed by duplex PCR targeting the flaB and the secY genes. For the detection of Seewis virus, lung-derived DNA was tested via RT-PCR targeting the nucleocapsid gene. Results: Altogether, 42 of the 736 small mammals including 27 of 660 bank voles and 11 of 66 shrews, were positive for Leptospira spp., while Sorex spp. (14.7%) showed significantly higher prevalences compared to bank voles (4.1%). Detected Leptospira spp. were pathogenic species other than L. kirschneri. Significantly more Leptospira-positive bank voles were found at H sites than at L sites. Altogether 22.2% of positive bank voles were infected with PUUV. Double infection of PUUV and Leptospira spp. occurrence in bank voles is 1.86 times (OR = 1.86; 95% CI: 0.72-4.73) more likely than infections with each pathogen separately. Discussion: Leptospira- positive bank voles are focally positively associated with PUUV infection in bank voles and with human hantavirus cases. It should be considered that shrews may serve as Leptospira spp. reservoirs. [ABSTRACT FROM AUTHOR]

The vast number of plant secondary metabolites (PSMs) produced by higher plants has generated many efforts to exploit their potential for pest control. We performed a systematic literature search to retrieve relevant publications, and we evaluated these according to PSM groups to derive information about the potential for developing plant-derived rodent repellents. We screened a total of 54 publications where different compounds or plants were tested regarding rodent behavior/metabolism. In the search for widely applicable products, we recommend multi-species systematic screening of PSMs, especially from the essential oil and terpenoid group, as laboratory experiments have uniformly shown the strongest effects across species. Other groups of compounds might be more suitable for the management of species-specific or sex-specific issues, as the effects of some compounds on particular rodent target species or sex might not be present in non-target species or in both sexes. Although plant metabolites have potential as a tool for ecologically-based rodent management, this review demonstrates inconsistent success across laboratory, enclosure, and field studies, which ultimately has lead to a small number of currently registered PSM-based rodent repellents. [ABSTRACT FROM AUTHOR]