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BACKGROUND: Understanding movement patterns of rodent pests is essential for planning management strategies. Currently, for many rural village contexts, there is limited information on how rodents move between domestic and peridomestic areas, and the surrounding habitats. We investigated movement of the multimammate rat, Mastomys natalensis and the black rat, Rattus rattus in nine villages in Kilombero District, Tanzania. We used Rhodamine B (RhB) baits placed inside houses (R. rattus preferred habitat) in five villages and placed outside (M. natalensis preferred habitat) in four villages. RESULTS: Whilst both species were rarely captured in their nonpreferred habitat (5% M. natalensis inside houses; 23% R. rattus outside houses), evidence of RhB consumption when bait was in nonpreferred habitat was high for both species (50% M. natalensis; 57% R. rattus), indicating frequent movement to nonpreferred habitats. Whilst R. rattus movement distances were consistent with previous studies (maximum 81 m), within our village context, M. natalensis moved further (maximum 132 m) compared to previous published studies. Although bait consumption rates varied seasonally, we found no evidence that utilization of nonpreferred habitat varied seasonally. M. natalensis females moved into houses more frequently than males, whilst immature R. rattus moved outside houses more than mature individuals. CONCLUSION: These findings highlight the dynamic movement patterns of commensal rodents with implications for control and disease transmission. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The circulation of Leptospira has been linked to various occupational activities globally. This study investigated the seroprevalence of Leptospira spp. in rodents and livestock (cattle and goats) in three settlements/villages involved in agriculture, livestock keeping, and mixed agriculture and livestock in the Kilombero district, Tanzania. Methods: Data were collected during the wet and dry seasons. A total of 179 rodents were live-captured from selected habitats. Livestock samples were collected from 80 cattle in a livestock settlement and 120 goats from both livestock and mixed agricultural–livestock settlements. The microscopic agglutination test was utilized to identify Leptospira serovars. Results: The seroprevalence of Leptospira spp. was 17.3% in rodents (21.7% in Mastomys natalensis and 3.9% in Rattus rattus) and 8.3% in livestock (13.5% in cattle and 12.6% in goats). The prevalence among rodents and livestock differed between settlements (p = 0.01). A higher prevalence was observed among rodents in the agricultural settlement relative to the other settlements. A higher prevalence of antibodies in livestock was observed in the livestock settlement compared with the mixed agricultural–livestock settlement. The Leptospira serovars Sokoine (serogroup Icterohaemorrhagiae) and Hebdomadis (serogroup Hebdomadis) were detected in both rodents and livestock. The serovars Hardjo (serogroup Sejroe) and Gripothyphosa (serogroup Gripothyphosa) were found exclusively in cattle, whereas the serovars Pomona (serogroup Pomona) and Lora (serogroup Australis) were identified in rodents. Leptospira antibodies were found to be elevated during the rainy season compared with the dry season (p = 0.05) in all settlements, with the exception of rodents in the mixed agricultural–livestock settlement. Conclusions: This study demonstrates the presence of anti-Leptospira antibodies in rodents and livestock related to occupational activities in human settlements. It further demonstrates that wild animals (rodents) and livestock are reservoirs of Leptospira and are important in the epidemiology of leptospirosis. Management and control strategies should target both rodents and livestock. [ABSTRACT FROM AUTHOR]

Over the past decades, the number of arthropod-borne virus (arbovirus) outbreaks has increased worldwide. Knowledge regarding the sylvatic cycle (i.e., non-human hosts/environment) of arboviruses is limited, particularly in Africa, and the main hosts for virus maintenance are unknown. Previous studies have shown the presence of antibodies against certain arboviruses (i.e., chikungunya-, dengue-, and zika virus) in African non-human primates and bats. We hypothesize that small mammals, specifically rodents, may function as amplifying hosts in anthropogenic environments. The detection of RNA of most arboviruses is complicated by the viruses' short viremic period within their hosts. An alternative to determine arbovirus hosts is by detecting antibodies, which can persist several months. Therefore, we developed a high-throughput multiplex immunoassay to detect antibodies against 15 medically relevant arboviruses. We used this assay to assess approximately 1,300 blood samples of the multimammate mouse, Mastomys natalensis from Tanzania. In 24% of the samples, we detected antibodies against at least one of the tested arboviruses, with high seroprevalences of antibodies reacting against dengue virus serotype one (7.6%) and two (8.4%), and chikungunya virus (6%). Seroprevalence was higher in females and increased with age, which could be explained by inherent immunity and behavioral differences between sexes, and the increased chance of exposure to an arbovirus with age. We evaluated whether antibodies against multiple arboviruses co-occur more often than randomly and found that this may be true for some members of the Flaviviridae and Togaviridae. In conclusion, the development of an assay against a wide diversity of medically relevant arboviruses enabled the analysis of a large sample collection of one of the most abundant African small mammals. Our findings highlight that Mastomys natalensis is involved in the transmission cycle of multiple arboviruses and provide a solid foundation to better understand the role of this ubiquitous rodent in arbovirus outbreaks. Author summary: One of the main causes of zoonotic related human morbidity and mortality is the transmission of arthropod-borne viruses such as dengue virus, Yellow Fever virus, and chikungunya virus. These viruses cannot only infect humans but also livestock, pets, and wildlife, though our understanding of their non-human hosts remains limited. Rodents are thought to be an important host for these viruses because they can be abundant, often live near humans, and some are already known to be viral hosts. However, research has focused mostly on non-human primates, neglecting other potential wild hosts. To address this gap, we have developed a high-throughput antibody test to screen rodent blood against 15 different arboviruses. Our findings reveal that Mastomys natalensis, a common African rodent species, carries antibodies that (cross-)react against these viruses. We hypothesize that immunologically naïve juveniles may drive transmission, particularly during population outbreaks. These outbreaks coincide with environmental conditions that are favorable for mosquitoes, thus increasing the risk of spillover to humans, livestock, and wildlife. Understanding the role of rodents in arbovirus transmission dynamics is crucial for mitigating zoonotic disease risks. [ABSTRACT FROM AUTHOR]

Species richness, abundance, diversity, and distribution of rodents and shrews along altitudinal gradients in the Simien mountains national park, Ethiopia, were studied using Sherman traps. Rodents and shrews were trapped at four altitudinal ranges (2,800 m a.s.l., 3,200 m a.s.l., 3,600 m a.s.l. and 4,000 m a.sl.). A total of 202 individuals were captured, comprising 184 rodents and 18 shrews. In total, there were eight species of rodents and one shrew species. The relative abundances of Lophuromys simensis and Stenocephalemys albipes were the highest in the early dry season, dry season, and wet season. The relative abundances of Desmomys harringitoni (7.43%), Dendromys lovati (4.46%), and Mus imberbis (1.98%) were the lowest across the study area. The highest species diversity was recorded at an altitude of 2,800 m a.s.l. (H' = 1.82). Species composition of rodents and shrews found at altitudes of 2,800 m a.s.l. and 3,200 m a.s.l. were highly similar (Sij = 0.97363). In contrast, the least similar species composition was between altitudes of 2,800 m a.s.l. and 4,000 m a.s.l. (Sij = 0.15632). The abundance, distribution, and diversity of rodents and shrews were significantly correlated with altitude (p = 0.000). Species abundance, distribution, and diversity in the Simien Mountains National Park were significantly correlated with altitude (0.377) and habitat types (0.306). Species composition of small mammals varied among altitudes, seasons, and habitat types, with six rodents and one shrew species being endemic. Notably, the park is subjected to various environmental disturbances, such as fires, grazing, and agriculture, which can negatively impact these small mammals, particularly the endemic species. [ABSTRACT FROM AUTHOR]

We investigated the breeding activity of three sympatric rodent species: Stenocephalemys albipes, Mastomys awashensis, and Acomys cahirinus, in the semi-arid region of Tigray in northern Ethiopia, using mark-recapture data, to determine the influence of rainfall on their breeding patterns within exclosure (i.e., protected area from livestock grazing). Breeding activities of S. albipes and M. awashensis commenced during the wet season, continued into the early dry season, and ceased during the subsequent dry season. The proportion of breeding females reached its peak during the wet season, gradually declining until the dry season. In contrast, A. cahirinus exhibited a different breeding strategy, with year-round breeding, including during the dry season, a period characterized by limited resources. A significant difference in the proportion of breeding females among the three species was observed across seasons. Furthermore, all species shared a common trend of heightened breeding activity, particularly at the conclusion of the wet season and the onset of the early dry season. These findings enhance our understanding of the interplay between rainfall and seasonal breeding within exclosures, while other variables remain constant. Moreover, the region's future plans for managing rodents and the establishment of exclosures must take this information into account. [ABSTRACT FROM AUTHOR]

Understanding host population dynamics in connection to disease persistence is important for determining the epizootic risks present in plague foci. We used a capture-mark-recapture method to investigate the population dynamics of Mastomys natalensis and Lophuromys makundii in an active plague focus, in Mbulu District, Tanzania. We hypothesized higher abundance in plague-persistent locality and between habits and seasons. We found distinct patterns of abundance in M. natalensis between farm and forest habitats. The abundance was significantly higher in farms in plague persistent than non-plague persistent areas. The dry season showed a significant increase of abundance compared to the long rain season and the short rain season. A significant increase in breeding females was observed in farms in plague persistent than non-plague persistent localities while farms showed a significant decrease compared to forests. Dry season was associated with an increase in breeding females compared to the long rain season and the short rain season. Furthermore, the abundance of L. makundii showed a significant increase in forest in plague persistent than non-plague persistent localities. The abundance increased significantly during the dry season and long rain season compared to the short rain season. The proportion of breeding females was significantly higher in forests in plague persistent than non-plague persistent localities. The breeding females significantly increased during the dry and the short rain season than the long rain season. These findings contribute to our understanding of the ecological factors shaping the population dynamics of these species and their potential roles in plague persistence. [ABSTRACT FROM AUTHOR]

Despite its biogeographical uniqueness, where two vast savanna regions are separated by the Afromontane mosaic vegetation, there is a significant lack of small mammal sampling in the Tigray region of Ethiopia. Leveraging all our available data on rodents and shrews in the region, we tested the hypothesis that the Afromontane mosaic vegetation in the highlands acts as a barrier to gene flow between taxa found in the Somali-Masai and Sudanian savanna in the southeast and western lowland parts of the region, respectively. Morphological and DNA sequence analysis confirmed the presence of 23 species of small rodents and shrews in the region. We recorded 18 of these species in the Afromontane mosaic vegetation, seven species in the Sudanian savanna, and four species in the Somali-Masai savanna. Notably, the fauna of the Sudanian savanna was strikingly different from that of the Somali-Masai savanna at both intraspecific and interspecific levels, suggesting the northern Ethiopian highlands as a very strong biogeographic barrier for taxa adapted to arid lowlands. However, the reported species diversity remains provisional, and additional sampling from unexplored areas is needed. Furthermore, some of the reported taxa, in this study, such as Mus cf. tenellus, Crocidura cf. fuscomurina, Dendromus sp. indet. 2, and Otomys cf. cheesmani, require detailed taxonomic investigation and may represent new species. A robust understanding of the taxonomic diversity and distribution of the small mammals in the region is crucial for effective conservation planning as well as for addressing practical questions related to rodents, such as in public health and pest management. [ABSTRACT FROM AUTHOR]

This article provides an overview of the impact of rodents on agriculture, health, and biodiversity, with a particular focus on Africa. It acknowledges that while rodents make up a significant portion of mammalian species, only a small percentage of them have negative effects. The article highlights the 7th International Conference on Rodent Biology and Management, which concentrated on rodent biology and biodiversity in African highlands and mountains. It discusses the shift in focus from previous conferences, including increased research on fertility control of rodents and a greater emphasis on the One Health approach to rodent-borne diseases. The article covers various topics related to rodent biology and management, such as reducing flea and rodent populations simultaneously to prevent disease transmission and efforts in New Zealand to eradicate invasive rodents for the conservation of endemic wildlife. It also explores adaptations of rodent sensory systems, developments in rodent taxonomy, strategies for dealing with dietary toxins, and the use of African giant pouched rats for tasks like landmine detection and disease detection. The article underscores the importance of long-term population studies in understanding rodent populations and their impact on agriculture and human health. It concludes by acknowledging the contributions of researchers in the field and announcing the next International Conference on Rodent Biology and Management in 2025. [Extracted from the article]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Yersinia pestis is a historically important vector-borne pathogen causing plague in humans and other mammals. Contemporary zoonotic infections with Y. pestis still occur in sub-Saharan Africa, including Tanzania and Madagascar, but receive relatively little attention. Thus, the role of wildlife reservoirs in maintaining sylvatic plague and spillover risks to humans is largely unknown. The multimammate rodent Mastomys natalensis is the most abundant and widespread rodent in peri-domestic areas in Tanzania, where it plays a major role as a Y. pestis reservoir in endemic foci. Yet, how M. natalensis' immunogenetics contributes to the maintenance of plague has not been investigated to date. Here, we surveyed wild M. natalensis for Y. pestis vectors, i.e., fleas, and tested for the presence of antibodies against Y. pestis using enzyme-linked immunosorbent assays (ELISA) in areas known to be endemic or without previous records of Y. pestis in Tanzania. We characterized the allelic and functional (i.e., supertype) diversity of the major histocompatibility complex (MHC class II) of M. natalensis and investigated links to Y. pestis vectors and infections. We detected antibodies against Y. pestis in rodents inhabiting both endemic areas and areas considered non-endemic. Of the 111 nucleotide MHC alleles, only DRB*016 was associated with an increased infestation with the flea Xenopsylla. Surprisingly, we found no link between MHC alleles or supertypes and antibodies of Y. pestis. Our findings hint, however, at local adaptations towards Y. pestis vectors, an observation that more exhaustive sampling could unwind in the future. [ABSTRACT FROM AUTHOR]

The multimammate mice (Mastomys natalensis) is the most-studied rodent species in sub-Saharan Africa, where it is an important pest species in agriculture and carrier of zoonotic diseases (e.g. Lassa virus). Here, we provide a unique dataset that consists of twenty-nine years of continuous monthly capture-mark-recapture entries on one 3 ha mosaic field (MOSA) in Morogoro, Tanzania. It is one of the most accurate and long-running capture-recapture time series on a small mammal species worldwide and unique to Africa. The database can be used by ecologists to test hypotheses on the population dynamics of small mammals (e.g. to test the effect of climate change), or to validate new algorithms on real long-term field data (e.g. new survival analyses techniques). It is also useful for both scientists and decision-makers who want to optimize rodent control strategies and predict outbreaks of multimammate mice. [ABSTRACT FROM AUTHOR]

Rodent-borne diseases such as bubonic plague remain a significant threat to public health in tropical countries. In plague-endemic areas, little information exists on the factors triggering periodic bursts, thus rendering preparedness strategies for preventing the negative impacts of the deadly zoonosis difficult. In this study, we assessed how species richness, diversity, and community structure of rodents are associated with plague persistence in Mbulu District, Tanzania. Rodent data were collected using the removal trapping technique. We captured 610 rodents belonging to 12 species, with Mastomys natalensis recording highest abundance. There was significantly higher abundance and species richness in persistent than non-persistent plague locality. Also, house premises recorded significantly lower species richness than farm and forest habitats. Additionally, we found three broad rodent community structures that varied significantly between studied habitat types suggesting high rodent populations interaction at fine-scale resource abundance. The high abundance and diversity of plague-susceptible rodent reservoirs suggestively contribute to the plague persistence in the foci. These results may be useful to developing preparedness strategies in these areas to control plague outbreaks. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Evolutionary information on the greater cane rat (Thryonomys swinderianus) in the Eastern and Southern African regions is scarce, making population management and conservation of the species challenging. We studied T. swinderianus populations from two spatially isolated Eastern Arc Mountains in Tanzania to link molecular and geometric–morphological evidence to characterize these populations' diversity. Fecal samples (n = 50) and skulls (n = 99) of T. swinderianus were collected from Udzungwa (north and south) and Uluguru mountains (urban and rural sites) and analyzed using molecular and geomorphometry techniques. Molecular analysis grouped the population into three distinct clades based on the location where the samples were collected, while the morphometric method was not able to distinctively separate the populations. Both methods revealed that the population obeyed the isolation by distance model with higher genetic distance between the Udzungwa and Uluguru populations and lower distance between Uluguru urban and rural populations. Both Mahalanobis and Procrustes distances in skull landmarks between the Udzungwa and Uluguru populations were significantly higher across the dorsal, ventral, and lateral views of the skulls, suggesting strongly that molecular and morphometric methods applied together can be useful in characterizing the population traits of the least known species. Our study suggests genetic and morphometric methods could complement each other in understanding the evolutionary biology and within-species diversity of vertebrate species that do not exhibit strong intra-species differentiation. [ABSTRACT FROM AUTHOR]

Simple Summary: The interaction of small mammals in the ecosystem is not limited to humans and other wildlife; it also includes organisms that inhibit their bodies, so-called "parasites". Arthropod ectoparasites are a diverse and well-adapted group of invertebrates that live on the body surfaces of their hosts, typically vertebrates but rarely other invertebrates. Ectoparasites such as fleas and some mite species are of veterinary and medical importance because they are associated with the transmission of zoonotic diseases. The study determined factors influencing ectoparasite infestation on two rodent species on Mount Meru, one of Tanzania's most popular research and ecotourism sites. Host sex, species, and environmental temperature predicted ectoparasite infestation patterns in the two rodent species. We expected host density to predict parasite prevalences and abundances, because hosts in higher densities should have more parasites due to increased contact between individuals. However, temperature, not host density, affected ectoparasite distribution. Since temperatures decrease with elevation, parasite prevalences and abundances were lower at higher elevations, highlighting that cold conditions at higher elevations limit reproduction and development—this shows that higher elevation zones are ideal for conservation. Climate change causes organisms, including species that act as parasite reservoirs and vectors, to shift their distribution to higher altitudes, affecting wildlife infestation patterns. We studied how ectoparasite distributions varied with altitude using two rodent species, Montemys delectorum and Rhabdomys dilectus, at different elevations (1500–3500 m). The ectoparasites infesting the two rodent species were influenced by the host sex, species, and temperature. We expected host density to predict parasite infestation patterns, because hosts in higher densities should have more parasites due to increased contact between individuals. However, temperature, not host density, affected ectoparasite distribution. Since temperatures decrease with elevation, parasite prevalences and abundances were lower at higher elevations, highlighting that the cold conditions at higher elevations limit reproduction and development—this shows that higher elevation zones are ideal for conservation. The rodents and ectoparasite species described in this study have been reported as vectors of diseases of medical and veterinary importance, necessitating precautions. Moreover, Mount Meru is a refuge for a number of endemic and threatened species on the IUCN Red List. Thus, the parasitic infection can also be an additional risk to these critical species as well as biodiversity in general. Therefore, our study lays the groundwork for future wildlife disease surveillance and biodiversity conservation management actions. The study found a previously uncharacterized mite species in the Mesostigmata group that was previously known to be a parasite of honeybees. Further investigations may shed light into the role of this mite species on Mount Meru. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The black rat is considered one of the world's top pests. With increased restrictions on rodenticides, new alternatives to manage rats are urgently needed. Research on the use of contraceptive hormones, levonorgestrel (LE), and quinestrol (QU), have been evaluated against some rodent species, and this research is the first study to assess these on black rats. Hormones were incorporated into rodent bait at 10 and 50 ppm concentrations singly and in combination (EP‐1). Groups of 10 animals of each sex were fed the baits over 7 days. Lower bait consumption was observed with slight body mass reductions. On dissection, it was observed that the uterus was in a state of edema and male reproductive organs weighed less with reduced sperm counts/motility. The 2 most promising baits, 50 ppm QU and EP‐1, were used to assess impact on pregnancy and litter size. Pregnancy was reduced from 70% success when both males and females consumed untreated bait, down to 30% when males had consumed contraceptive bait but females had not, and down to 0% when females had consumed contraceptive bait, regardless of whether they had paired with a treated or untreated male. Litter size in the untreated pairs was 8 pups, but only 4 pups in those cases where the male only had consumed the contraceptive. Further studies should investigate how long the effect lasts and its reversibility. Field studies at the population level may also shed light on the practicality of using contraceptive baits for black rats in different habitats. [ABSTRACT FROM AUTHOR]

Understanding species distribution across elevational gradients is crucial for developing conservation strategies for montane biotic systems. A survey of small mammals was conducted on Mount Meru at six elevations, ranging between 1500 m and 3650 m. A total of 803 small mammal individuals, including 2 shrew species and 13 rodent species, were documented. Of these, Crocidura newmarki and Lophuromys verhageni were endemic on Mount Meru. Species richness was highest at mid–elevations, which is in line with the global pattern for small mammals. Prior to our study, the most complete data on small mammals on Mount Meru was collected in 2009. Our study provides an opportunity to show how small mammal elevational distribution has changed, over the last decade. We found six species (Arvicanthis niloticus, Mastomys natalensis, Lemniscomys striatus, Dasymys incomtus, Cricetomys ansorgei, and Montemys delectorum), which were not documented in 2009, but did not find Otomys tropicalis. Interestingly, the community composition at higher elevations in 2021 resembles that at lower elevations in 2009, suggesting that small mammal species have moved their range upward over time. Climate change could be a factor associated with the distributional shift found. [ABSTRACT FROM AUTHOR]

Threats to ecosystems are ever increasing from different drivers mostly being linked to anthropogenic activities. This has brought about various measures to restore/protect the wildlife in these areas. Considering the background of most protected areas in East Africa, small mammals have been given least attention, compared with large mammals, although they play a fundamental role in maintaining ecosystem health. It is therefore necessary to understand how small mammals are distributed in any given ecosystem as a baseline information to enable holistic and informed management. We investigated the diversity and distribution of small mammals in the Selous ecosystem, Tanzania. Two methods were used; Capture Mark Recapture (CMR) using grids of 70 m x 70 m and random placement of havahart traps in the selected habitats. Between July 2018 and June 2020, a total of 887 individuals belonging to 20 species were captured in 28 224 trap nights with 3% trap success. The small mammal species captured consisted of rodents (91.8%), Macroscelidea (3.9%), Carnivores (2.4%) Eulipotyphla (1.6%), and Primates (0.3%). Acomys ngurni (36%) and Aethomys chrysophilus (17%) were the most captured species, whereas Atilax paludinosus (0.23%), Helogale pervula (0.23%), Rattus rattus (0.23%) and Galerella sanguinea (0.11%) were the least contributing species. Acomys ngurui and Lemniscomys rosalia were the most distributed species occurring in all four habitats, whereas Cricetomys ansorgei, Rattus rattus, Mungos mungo and Genetta genetta had low occurrence. Grammomys selousi is reported for the first time in the northern part of the Rufiji River. Acomys ngurni abundance differed significantly (χ2 = 12, df = 3, p = 0.007) between the four habitats being higher in the seasonal riverine forest and across seasons (χ2 = 6, df = 2, p = 0.049), with more individuals occurring in the wet season. The Sable Forest habitat had the highest species diversity (H' = 2.065) and the lowest diversity (H' = 1.506) was recorded in perennial riverine forest/thickets. The highest species diversity (H' = 1.65) was recorded in the dry season and the lowest diversity in the wet season (H' = 1.445). Most small mammals were associated with seasonal riverine forest than other habitats. Overall, the results from this study show that, the park is rich in small mammal fauna. Therefore, considerations in updating the General Management Plan (GMP) and other plans to include the small mammals in the park management actions is recommended. [ABSTRACT FROM AUTHOR]

We assessed the habitat association of the diversity and abundance of small mammals in the Ukaguru Mountains within the Eastern Arc Mountains, Tanzania. An estimation of the vegetation parameters and live-trapping of small mammals for three consecutive nights per month for 21 months were carried out in farmland, disturbed and intact forests. A total of 1196 individual small mammals comprising 13 species were captured. Species diversity and evenness in intact forest were much higher compared to disturbed forest. Principal component analysis (PCA) explained 87.7% of the variance with two factors. The study suggests vegetation and habitat disturbances are factors responsible for the observed diversity of small mammals in the Ukaguru Mountains. Mastomys natalensis, Mus triton and Praomys delectorum accounted for 90.0% of total captures. M. triton and M. natalensis were the most abundant in farmland with 46.8 and 42.8% of total captures respectively and associated with the herbaceous vegetation. P. delectorum correlated with litter depth and trees and accounted for 90.0 and 80.0% total captures in disturbed and intact forests respectively but the mean abundances in both habitats were not significantly different (p = 0.72). [ABSTRACT FROM AUTHOR]

Multimammate mice (Mastomys natalensis) are a key rodent pest species to cereal crop production in Sub-Saharan Africa. This study aimed at generating information on the population fluctuation and breeding patterns of M. natalensis in a maize dominated agro-ecosystem in the Mayuge district, Eastern Uganda. The area is characterised by a bimodal rainfall pattern with rains in the periods March to May and August to November. A Capture–Mark–Recapture study was established in cultivated and fallow field habitats with, in each habitat, two plots of 60 m by 60 m with 49 evenly spaced trapping points. Trapping was conducted monthly for three consecutive nights, and the study extended from January 2016 to June 2018. A Generalised Linear Mixed Model analysis showed significantly higher population density estimates (β = 0.69, p < 0.0001) in fallow land compared to cultivated fields, and also significantly higher density estimates(β = 0.75, p = 0.006) in the first wet season and lowest in the first dry season. The percentage breeding females differed significantly across months (χ2 = 27.05, df = 11, p = 0.003) and seasons (χ2 = 17.64, p = 0.0003). Breeding females occurred throughout all the months of trapping, but with significantly higher percentages in the months of March to July (i.e. first wet season extending to second dry season) and generally lowest in the first dry months (i.e. January and February in 2017, and February 2018). The results of this study have important consequences for the timing of control efforts, and recommends that control should be initiated during the dry seasons prior to wet seasons to counteract potential damaging population build up in later wet seasons when crop planting is expected. [ABSTRACT FROM AUTHOR]

Praomys delectorum occurs abundantly in both disturbed and intact forests in the Ukaguru Mountains within the Eastern Arc Mountains (EAM), Morogoro, Tanzania. While previous studies have reported that anthropogenic disturbances such as grazing, wood cutting, and harvesting have a positive effect on the population density of P. delectorum, the impact of habitat disturbance on its demographic traits is still unknown. We performed a capture–mark–recapture study in both disturbed and intact forests from June 2018 to February 2020 in order to investigate the effects of habitat disturbance on abundance and two demographic traits: survival and maturation of P. delectorum in the Ukaguru Mountains. We found no variation in abundance or maturation between intact and disturbed forests, but habitat type did affect survival. However, this effect was sex‐dependent since female survival was higher in disturbed forests, while male survival remained similar across the two forest types potentially due to differences in predation pressure or food availability between the two habitats. Continuous demographic monitoring of P. delectorum in EAM is necessary given that the increasing human population surrounding the landscape is leading to higher deforestation rates and expansion of the pine plantation in the forest reserve. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV; genus Hepacivirus) represents a major public health problem, infecting about three per cent of the human population. Because no animal reservoir carrying closely related hepaciviruses has been identified, the zoonotic origins of HCV still remain unresolved. Motivated by recent findings of divergent hepaciviruses in rodents and a plausible African origin of HCV genotypes, we have screened a large collection of small mammals samples from seven sub-Saharan African countries. Out of 4,303 samples screened, eighty were found positive for the presence of hepaciviruses in twenty-nine different host species. We, here, report fifty-six novel genomes that considerably increase the diversity of three divergent rodent hepacivirus lineages. Furthermore, we provide strong evidence for hepacivirus co-infections in rodents, which were exclusively found in four sampled species of brush-furred mice. We also detect evidence of recombination within specific host lineages. Our study expands the available hepacivirus genomic data and contributes insights into the relatively deep evolutionary history of these pathogens in rodents. Overall, our results emphasize the importance of rodents as a potential hepacivirus reservoir and as models for investigating HCV infection dynamics. [ABSTRACT FROM AUTHOR]

Rodents generate negative consequences for smallholder farmers in Africa that directly impact household and livestock damage, food security, and public health. Ecologically Based Rodent Management (EBRM) seeks sustainable solutions for the mitigation of rodent damage through assessments of rodent population dynamics, agro‐ecosystems, and socio‐cultural contexts. We adopt a comparative approach across 3 rural Afro‐Malagasy smallholder farming regions in South Africa, Tanzania, and Madagascar to assess the household impacts of rodent pests and current perceptions and preferences associated with several rodent control measures. We conducted focus group questionnaires and interviews in different study site locations. Rodents assert multiple impacts on Afro‐Malagasy farmers demonstrating recurrent and emerging agricultural and household costs, and public health impacts. We identify a significant knowledge gap in educating communities about the application of different EBRM approaches in favor of acute poisons that are perceived to be more effective. Cultural issues and taboos also have a significant impact on the social acceptance of rodent hunting as well as biological control using indigenous predators. We advocate for an enhanced investigation of the socio‐cultural beliefs associated with different rodent practices to understand the factors underlying social acceptance. A collaborative approach that integrates the perspectives of target communities to inform the design of EBRM initiatives according to the specific agro‐ecosystem and socio‐cultural context is necessary to ensure programmatic success. [ABSTRACT FROM AUTHOR]

Investigation of home ranges, sex ratio and recruitment of the multimammate rat (Mastomys natalensis) in semi-arid areas of Tanzania was conducted in maize and fallow fields using the capture-mark-release (CMR) technique. The aim of this study was to generate useful data for the management of M. natalensis. The relative home range size of M. natalensis was significantly higher during the wet [544 m2 ± 25 standard error (SE)] than during the dry (447 m2 ± 18 SE) season, in males (521 m2 ± 23 SE) than in females (450 m2 ± 17 SE) and in adults (576 m2 ± 34 SE) than in juveniles (459 m2 ± 16 SE). However, there were no significant differences between habitats. Sex ratio was not significantly different (p = 0.44) between habitats. Recruitment was significantly higher (p = 0.000) in maize fields (mean = 0.43) than in fallow land (mean = 0.32) and differed significantly over time (p < 0.0001) with the highest recruitment recorded from April to July and the lowest from October to December. Management strategies should focus on managing rodents inhabiting maize fields using methods that affect their recruitment in order to reduce the population increase of M. natalensis. [ABSTRACT FROM AUTHOR]

The abundance and microhabitat use of rodents were investigated in four different habitats: two rain-fed crop fields with differing stone bund density, an irrigated field and bushland. A total of 444 individual small mammals belonging to six rodent and one shrew species were recorded in trapping grids and line transects. Of these, 230 individuals (52%) belonged to three pest rodent species of crop fields in northern Ethiopia: Stenocephalemys albipes (65%), Mastomys awashensis (25%) and Arvicanthis niloticus (10%). Population abundance of the three species was higher in the early dry season compared to the rainy season. While the bushland was significantly (p < 0.05) favoured by S. albipes and M. awashensis in both seasons, the irrigated field was preferred by Arvicanthis niloticus in the early dry season. In the early dry season, the microhabitat use of A. niloticus was strongly associated with the type of ground cover (herb) (R²adj = 0.152, P < 0.01). While M. awashensis was associated with vegetation density (R²adj = 0.13, P < 0.01), S. albipes was associated with vegetation cover (R²adj = 0.102, P < 0.001). The findings indicate that co-occurring pest rodent species prefer different microhabitats. Understanding their co-occurrence particularly in crop fields is vital for crop protection as they are known serious agricultural pests in northern Ethiopia. [ABSTRACT FROM AUTHOR]

A study was conducted in Mabira Central Forest Reserve in Uganda to determine rodent species composition, relative abundance, and habitat association. A total of 1,030 rodents belonging to 14 species were captured on 10,584 trap nights. Rodent species recorded include: Lophuromys stanleyi, Hylomyscus stella, Praomys jacksoni, Mastomys natalensis, Lophuromys ansorgei, Lemniscomys striatus, Aethomys hindei, Mus triton, Mus minutoides, Deomys ferrugineus, Gerbilliscus kempi, Rattus rattus, Grammomys kuru, and Hybomys univittatus. Overall, L. stanleyi (23.7%) was the most dominant species followed by H. stella, P. jacksoni, and M. natalensis. Species richness and evenness was highest in the regenerating forest habitat and least in the intact forest habitat. Rodent abundance was significantly affected by habitat type. The regenerating forest habitat had the highest number of animals, while the lowest numbers were observed in the depleted forest habitat. Species diversity was higher in regenerating forest habitat and lowest in the intact forest. The three habitats appeared distinct in terms of rodent species composition and there was a strong association between the two trapping grids in the same habitat type. All ordination plots showed that different rodent species consistently associated with distinct habitats. Habitat type and seasonal changes influenced rodent composition, relative abundance and habitat association. Composition of rodent community reflected the level of habitat degradation and can be used as a proxy for evaluating the biodiversity of lowland tropical forests. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the potential use of normalized difference vegetation index (NDVI) from satellite-derived remote sensing data for monitoring rodent abundance in semi-arid areas of Tanzania. We hypothesized that NDVI could potentially complement rainfall in predicting rodent abundance spatially and temporally. NDVI were determined across habitats with different vegetation types in Isimani landscape, Iringa Region, in the southern highlands of Tanzania. Normalized differences in reflectance between the red (R) (0.636–0.673 mm) and near-infrared (NIR) (0.851–0.879 mm) channels of the electromagnetic spectrum from the Landsat 8 [Operational Land Imager (OLI)] sensor were obtained. Rodents were trapped in a total of 144 randomly selected grids each measuring 100 × 100 m2, for which the corresponding values of NDVI were recorded during the corresponding rodent trapping period. Raster analysis was performed by transformation to establish NDVI in study grids over the entire study area. The relationship between NDVI, rodent distribution and abundance both spatially and temporally during the start, mid and end of the dry and wet seasons was established. Linear regression model was used to evaluate the relationships between NDVI and rodent abundance across seasons. The Pearson correlation coefficient (r) at p ≤ 0.05 was carried out to describe the degree of association between actual and NDVI-predicted rodent abundances. The results demonstrated a strong linear relationship between NDVI and actual rodent abundance within grids (R2 = 0.71). NDVI-predicted rodent abundance showed a strong positive correlation (r = 0.99) with estimated rodent abundance. These results support the hypothesis that NDVI has the potential for predicting rodent population abundance under smallholder farming agro-ecosystems. Hence, NDVI could be used to forecast rodent abundance within a reasonable short period of time when compared with sparse and not widely available rainfall data. [ABSTRACT FROM AUTHOR]

Pest rodents remain key biotic constraints to cereal crops production in the East African region where they occur, especially in seasons of outbreaks. Despite that, Uganda has scant information on rodents as crop pests to guide effective management strategies.A capture–mark–recapture (CMR) technique was employed to study the ecology of small rodents, specifically to establish the species composition and community structure in a maize‐based agro ecosystem. Trapping of small rodents was conducted in permanent fallow land and cultivated fields, with each category replicated twice making four study grids. At each field, a 60 × 60 m grid was measured and marked with permanent trapping points spaced at 10 × 10 m, making a total of 49 trapping points/grids. Trapping was conducted monthly at 4‐week interval for three consecutive days for two and half years using Sherman live traps.Eleven identified small rodent species and one insectivorous small mammal were recorded with Mastomys natalensis being the most dominant species (over 60.7%). Other species were Mus triton (16.1%), Aethomys hendei (6.7%), Lemniscomys zebra (5.2%), Lophuromys sikapusi (4.8%), Arvicanthis niloticus (0.9%), Gerbilliscus kempi (0.1%), Graphiurus murinus (0.1%), Steatomys parvus (0.1%), Dasymys incomtus (0.1%), and Grammomys dolichurus (0.1%). Spatially, species richness differed significantly (p = 0.0001) between the studied field habitats with significantly higher richness in fallow land compared with cultivated fields.Temporally, total species richness and abundance showed a significant interaction effect over the months, years, and fields of trapping with significantly (p = 0.001) higher abundances during months of wet seasons and in the first and third year of trapping. In terms of community structure, higher species diversity associated more with fallow field habitats but also with certain rare species found only in cultivated fields.Synthesis and applications. Based on these findings, management strategies can be designed to target the key pest species and the most vulnerable habitats thus reducing the impact they can inflict on field crops. [ABSTRACT FROM AUTHOR]

Exploration and activity are often described as trade-offs between the fitness benefits of gathering information and resources, and the potential costs of increasing exposure to predators and parasites. More exploratory individuals are predicted to have higher rates of parasitism, but this relationship has rarely been examined for virus infections in wild populations. Here, we used the multimammate mouse Mastomys natalensis to investigate the relationship between exploration, activity, and infection with Morogoro virus (MORV). We characterized individual exploratory behavior (open field and novel object tests) and activity (trap diversity), and quantified the relationship between these traits and infection status using linear regression. We found that M. natalensis expresses consistent individual differences, or personality types, in exploratory behavior (repeatability of 0.30, 95% CI: 0.21–0.36). In addition, we found a significant contrasting effect of age on exploration and activity where juveniles display higher exploration levels than adults, but lower field-activity. There was however no statistical evidence for a behavioral syndrome between these 2 traits. Contrary to our expectations, we found no correlation between MORV infection status and exploratory behavior or activity, which suggests that these behaviors may not increase exposure probability to MORV infection. This would further imply that variation in viral infection between individuals is not affected by between-individual variation in exploration and activity. [ABSTRACT FROM AUTHOR]

Rodent pest management traditionally relies on some form of lethal control. Developing effective fertility control for pest rodent species could be a major breakthrough particularly in the context of managing rodent population outbreaks. This laboratory-based study is the first to report on the effects of using fertility compounds on an outbreaking rodent pest species found throughout sub-Saharan Africa. Mastomys natalensis were fed bait containing the synthetic steroid hormones quinestrol and levonorgestrel, both singly and in combination, at three concentrations (10, 50, 100 ppm) for 7 days. Consumption of the bait and animal body mass was mostly the same between treatments when analysed by sex, day and treatment. However, a repeated measures ANOVA indicated that quinestrol and quinestrol + levonorgestrel treatments reduced consumption by up to 45%, particularly at the higher concentrations of 50 and 100 ppm. Although there was no clear concentration effect on animal body mass, quinestrol and quinestrol + levonorgestrel lowered body mass by up to 20% compared to the untreated and levonorgestrel treatments. Quinestrol and quinestrol + levonorgestrel reduced the weight of male rat testes, epididymis and seminal vesicles by 60-80%, and sperm concentration and motility were reduced by more than 95%. No weight changes were observed to uterine and ovarian tissue; however, high uterine oedema was observed among all female rats consuming treated bait at 8 and 40 days from trial start. Trials with mate pairing showed there were significant differences in the pregnancy rate with all treatments when compared to the untreated control group of rodents. [ABSTRACT FROM AUTHOR]

Infectious diseases of wildlife are typically studied using data on antibody and pathogen levels. In order to interpret these data, it is necessary to know the course of antibodies and pathogen levels after infection. Such data are typically collected using experimental infection studies in which host individuals are inoculated in the laboratory and sampled over an extended period, but because laboratory conditions are controlled and much less variable than natural conditions, the immune response and pathogen dynamics may differ. Here, we compared Morogoro arenavirus infection patterns between naturally and experimentally infected multimammate mice ( Mastomys natalensis). Longitudinal samples were collected during three months of bi-weekly trapping in Morogoro, Tanzania, and antibody titer and viral RNA presence were determined. The time of infection was estimated from these data using a recently developed Bayesian approach, which allowed us to assess whether the natural temporal patterns match the previously observed patterns in the laboratory. A good match was found for 52% of naturally infected individuals, while most of the mismatches can be explained by the presence of chronically infected individuals (35%), maternal antibodies (10%), and an antibody detection limit (25%). These results suggest that while laboratory data are useful for interpreting field samples, there can still be differences due to conditions that were not tested in the laboratory. [ABSTRACT FROM AUTHOR]

Density-dependent shifts in population processes like territoriality, reproduction, dispersal, and parasite transmission are driven by changes in contacts between individuals. Despite this, surprisingly little is known about how contacts change with density, and thus the mechanisms driving density-dependent processes. A simple linear contact-density function is often assumed, but this is not based on a sound basis of empirical data. We addressed this question using a replicated, semi-natural experiment in which we measured contacts at feeding stations between multimammate mice, Mastomys natalensis, across ten distinct, linearly increasing densities between 10 and 272 animals/ha. Unexpectedly, unique contacts increased not linearly but sigmoidally with density, which we attribute to the species' scramble competition mating system, small-scale dominance/avoidance and absence of territoriality. These results provide new insights into how species' characteristics can relate to density-dependent changes in contacts, and the unexpected shape of the contact-density function warrants that density-dependence in ecological models, such as parasite transmission models, must be parameterized with care. [ABSTRACT FROM AUTHOR]

Rodent pests are especially problematic in terms of agriculture and public health since they can inflict considerable economic damage associated with their abundance, diversity, generalist feeding habits and high reproductive rates. To quantify rodent pest impacts and identify trends in rodent pest research impacting on small-holder agriculture in the Afro-Malagasy region we did a systematic review of research outputs from 1910 to 2015, by developing an a priori defined set of criteria to allow for replication of the review process. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We reviewed 162 publications, and while rodent pest research was spatially distributed across Africa (32 countries, including Madagascar), there was a disparity in number of studies per country with research biased towards four countries (Tanzania [25%], Nigeria [9%], Ethiopia [9%], Kenya [8%]) accounting for 51% of all rodent pest research in the Afro-Malagasy region. There was a disparity in the research themes addressed by Tanzanian publications compared to publications from the rest of the Afro-Malagasy region where research in Tanzania had a much more applied focus (50%) compared to a more basic research approach (92%) in the rest of the Afro-Malagasy region. We found that pest rodents have a significant negative effect on the Afro-Malagasy small-holder farming communities. Crop losses varied between cropping stages, storage and crops and the highest losses occurred during early cropping stages (46% median loss during seedling stage) and the mature stage (15% median loss). There was a scarcity of studies investigating the effectiveness of various management actions on rodent pest damage and population abundance. Our analysis highlights that there are inadequate empirical studies focused on developing sustainable control methods for rodent pests and rodent pests in the Africa-Malagasy context is generally ignored as a research topic. [ABSTRACT FROM AUTHOR]

Many emerging infections are RNA virus spillovers from animal reservoirs. Reservoir identification is necessary for predicting the geographic extent of infection risk, but rarely are taxonomic levels below the animal species considered as reservoir, and only key circumstances in nature and methodology allow intrinsic virus-host associations to be distinguished from simple geographic (co-)isolation. We sampled and genetically characterized in detail a contact zone of two subtaxa of the rodent Mastomys natalensis in Tanzania. We find two distinct arenaviruses, Gairo and Morogoro virus, each spatially confined to a single M. natalensis subtaxon, only co-occurring at the contact zone’s centre. Inter-subtaxon hybridization at this centre and a continuum of quality habitat for M. natalensis show that both viruses have the ecological opportunity to spread into the other substaxon’s range, but do not, strongly suggesting host-intrinsic barriers. Such barriers could explain why human cases of another M. natalensis-borne arenavirus, Lassa virus, are limited to West Africa. [ABSTRACT FROM AUTHOR]

The lesser pouched rat, Beamys hindei, is a small rodent that is patchily distributed in the Eastern Arc Mountains and coastal forests in East Africa. The ecology of this species and its current distribution in coastal forests is not well known. Therefore, we conducted a study in selected coastal forests to assess the current distribution of the species and to investigate the population ecology in terms of abundance fluctuations and demographic patterns. Assessments of the species distribution were conducted in 5 forests through trapping with Sherman live traps. Data on ecology were obtained from monthly capture-mark-recapture studies conducted for 5 consecutive nights per month in two 1 ha grids set in Zaraninge Forest over a 2-year period. The results indicate the presence of B. hindei in 3 forests where it was not previously recorded. The population abundance estimates ranged from 1 to 40 animals per month, with high numbers recorded during rainy seasons. Reproduction patterns and sex ratios did not differ between months. Survival estimates were not influenced by season, and recruitment was low, with growth rate estimates of 1 animal per month. These estimates suggest a stable population of B. hindei in Zaraninge Forest. Further studies are recommended to establish the home range, diet and burrowing behavior of the species in coastal forests in East Africa. [ABSTRACT FROM AUTHOR]

Resistance of rodents to anticoagulant rodenticides has emerged in several areas across the world. Single nucleotide mutations in the vkorc1 gene have been shown to elicit various levels of anticoagulant resistance, and these mutations are prevalent in several Rattus and Mus musculus populations. In sub-Saharan Africa, the Natal multimammate mouse, Mastomys natalensis, is one of the most damaging pests to crops, and anticoagulant poisons such as bromadiolone are frequently used to control these rodents in agricultural fields. Here, we investigate if vkorc1 shows any polymorphism in natural populations of M. natalensis. We sequenced the third exon of vkorc1 of 162 M. natalensis captured from 14 different agricultural sites in Morogoro Region, Tanzania. In addition to 6 SNPs in the noncoding flanking region, we detected 3 nonsynonymous SNPs in this exon: 10 animals (6.2%) carried a Leu108Val variant, 2 animals (1.2%) an Ala140Thr variant, and 1 animal (0.6 %) an Arg100His variant, all 3 in heterozygous form. Ala140Thr is just one residue from a mutation known to be involved in anticoagulant resistance in Rattus and Mus. While in vitro or in vivo experiments are needed to link vkorc1 genetic polymorphisms to level of VKOR activity and anticoagulant susceptibility, our results suggest that M. natalensis individuals may vary in their response to anticoagulant rodenticides. This is the first vkorc1 sequence data from a species outside the Rattus or Mus genera, and for the first time from a rodent species endemic to Africa. [ABSTRACT FROM AUTHOR]

Context. Plague is a serious health problem in northern Tanzania, with outbreaks since 2008 in two districts located in Rift Valley. There is dearth of knowledge on diversity of small mammal and flea fauna occurring in this plague focus. Knowledge on interactions between fleas and rodent species that harbour the plague bacterium, Yersinia pestis, is important for developing strategies for control and prevention of plague. Aims. This study aims to show how rodents and fleas are associated with each other in the plague focus. Methods. Animals were trapped bimonthly from 2009 to 2012 in different habitats. The fur of animals was brushed to collect fleas, which were identified and quantified. Network analysis methods, randomisation and rarefaction curves were used to show how hosts and fleas are associated. Key results. Thirteen speciesofrodents were associated with26species of fleasofwhichDinopsyllus lypusus, Xenopsylla brasiliensis and X. cheopis are confirmed efficient vectors of Y. pestis. Randomisation and rarefaction curves established that Lophuromys flavopunctatus had significantly higher flea species richness (n= 9) than did all other hosts, whereas Xenopsylla cheopis and Dinopsyllus spp. showed greater host species richness than did other species of fleas. There was no significant correlation between host sex and flea abundance (X[sup 2] = 0.8, d.f.= 6,P= 0.371), but significant differences between reproductive states (adults had more fleas than did subadults) were observed, which probably reflected typical positive correlation between size and flea abundance (X[sup 2] = 4.1955, d.f.=1, P= 0.040). Conclusions. The plague outbreak focus in northern Tanzania has a diverse fauna of rodents and fleas with multiple patterns of association and connectivity. Implications. Existence of diverse populations of rodents associated with a large number of flea species, some of which are efficient plague vectors, increases the potential for persistence and transmission of plague to humans in northern Tanzania. [ABSTRACT FROM AUTHOR]

Context Reproduction and survival are two of the most important demographic factors that play a major role in changing population abundances of pest species over time and space, solid understanding of which is a useful input to forecast future population changes for proactive management. Aims. We investigated the effects of rainfall, crop-development stage and density of stone bunds on reproductive patterns, and the effects of stone-bund density and sex on survival probabilities of two widespread rodent species (Mastomys awashensis and Arvicanthis dembeensis) in Ethiopian highlands. Methods. Rodent population dynamics were monitored from April 2007 to February 2011, using capture-mark-recapture (CMR) technique in four 60 x 60 m permanent square grids for four consecutive cropping seasons. Two of the grids represented fields with low stone-bund density (LSBD, ~15 m apart) and the other two represented fields with high stone-bund density (HSBD, ~10 m apart). Key results. Reproduction was seasonal, commencing during the wet season following the rain and continuing through the early dry season. We found an increase in the abundance of reproductively active female individuals of both species towards the milky and fruiting crop stages and around harvest period. We found no strong difference in survival probability between the two rodent species with variation in stone-bund density and sex. Conclusion. Stone bunds play a minor role in the reproduction and survival of the rodent species at the observed abundances. Implications. In terms of pest management, the high local survival rates estimated for both rodent species matter more than survival differences owing to variations in stone-bund density and sex. [ABSTRACT FROM AUTHOR]

Context. Toe clipping is a widely used method for permanent marking of small mammals, but its effects are not well known, despite the ethical and scientific implications. Most studies do not find any clear effects, but there is some indication that toe clipping can affect survival in specific cases. Although effects on survival are arguably the most important, more subtle effects are also plausible, yet very few studies have included body condition and none has investigated effects on mobility. Aims. We analysed the effects of toe clipping on free-living Mastomys natalensis, a common, morphologically and behaviourally intermediate small rodent. Methods. Using a 17-year capture-mark-recapture dataset, we compared movement, body weight and survival between newly and previously clipped animals, and tested whether any of these parameters correlated with the number of clipped toes. Key results. No evidence for a correlation between total number of clips and any of the variables was found. Newly clipped animals had a slightly smaller weight change and larger travel distance than did those that were already clipped, and we show that this is most likely due to stress caused by being captured, clipped and handled for the first time rather than to the actual clipping. Conclusions. The combination of trapping, handling and marking has a detectable effect on multimammate mice; however, there is no evidence for a clear effect of toe clipping. Implications. Our study suggests a re-evaluation of ethical guidelines on small-mammal experiments, so as to reach a rational, fact-based decision on which marking method to use. [ABSTRACT FROM AUTHOR]

The availability of resources, their effect on population density and territoriality, and the ways in which these factors are interwoven with mating systems are important determinants of small mammal space use. It is often difficult to study these patterns in an integrated way, however, especially because long-term data are needed but not readily available. In this paper, we investigate effects of population density, season and breeding status on home range patterns of the promiscuous rodent Mastomys natalensis using monthly capture-mark-recapture data collected over 17 years in a 3-ha grid. Home ranges were estimated using minimum convex polygons bounded by trap locations, and home range overlap and visitation rates were calculated as a measure of territoriality. As higher population densities coincide with increased resource availability, we predicted that home range sizes would correlate negatively with density. Furthermore, as M. natalensis is promiscuous and population densities are generally high, we predicted that territoriality would be low, and home range overlap would therefore be high. Contrary to expectations the home ranges of female adults increased with population density, although those of male adults and subadults followed the expected decrease. Home range overlap and visitation rates were generally high, and increased significantly with population density. More importantly, they were never lower than those of simulated datasets consisting of randomly moved home ranges. These results therefore suggest that M. natalensis displays a complete lack of territoriality that is rarely seen in small mammals but still meets predictions based on knowledge of density and mating system. [ABSTRACT FROM AUTHOR]

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The breeding dynamics of three species of rodents, Mastomys natalensis, Aethomys chrysophilus and Gerbilliscus vicina were investigated in a seasonal environment (wet versus dry) in Berega in the eastern parts of central Tanzania. Berega has a distinct unimodal rainfall pattern, with most rainfall from November to April/May. We hypothesized that breeding of rodents in central Tanzania would be confined to the wet season, when unlimited resources would be available for reproduction. We provide evidence of breeding discontinuity in the three species, showing that breeding was seasonally restricted to the wet season and early in the dry season. The observed discontinuity could largely be ascribed to variation in primary productivity between the wet and dry seasons. Reproductively active females were found in the population as early as November, a month into the rainy season, but when early rains occurred, some individuals were already breeding in October. Breeding was more intensive in the latter part of the wet season (March-May) and completely ceased during the dry season. For M. natalensis, survival was highest in the wet period and low in the dry season. The study provides knowledge on the breeding dynamics of rodents in central Tanzania, which can help farmers to take proactive rodent management decisions to prevent high rodent densities and reduce crop damage in the fields. Application of control measures by the community early in the season when populations of reproductive females is lowest will be most rewarding. [ABSTRACT FROM AUTHOR]

The prevalence of haemoparasites, leptospirosis and Yersinia pestis was investigated in rodents and shrews from Tanzania, Namibia and Swaziland. Blood smears originating from rodents and shrews from the three countries indicated the presence of Trypanosoma lewisi (72.7%; n =950), Bacillus spp. (25.6%; n =950), Borrelia sp. (0.01%; n =950) and bipolar coccobacilli (0.01%; n = 950). The blood smears from Namibia (n =26) had no haemoparasites while only 1.33% (n =75) of those from Swaziland showed presence of T. lewisi. Leptospira interrogans was found in rodent blood sera from Tanzania in the following serogroup proportions (n =350): Icterohaemorrhagiae (10.29%), Pomona (2.86%), Hardjo (1.14%), Bullum (0.86%), Grippotyphosa (1.43%) and Canicola (1.14%). Serodiagnosis of antibodies against the F 1 antigen of Y. pestis using the enzyme linked iInmunosorbent assay (ELISA) was negative for all the serum samples from central Tanzania, while two samples of serum from two species of rodents, Rhabdomyspumilio and Gerbilliscus leucogaster, collected in the Kavango Region of Namibia were positive. These results suggest an enzootic plague activity in this region in Namibia. It is concluded that zoonotic agents, that are infectious to humans, are prevalent in rodents and shrews in the three countries, and that local communities should apply rodent control measures to reduce the risk of human infections. [ABSTRACT FROM AUTHOR]

Context Rodent pests severely affect crop production, particularly in monocultures where one or two rodent pest species dominate. We predict higher species richness of native small mammal species in more heterogeneous mosaic (crop-fallow-bush) subsistence agro-ecosystems in Africa. Conservation and agro-ecological imperatives require that such diverse natural communities should be maintained and may benefit crop protection through limiting domination of pest species. Ecologically based rodent-management alternatives to rodenticides are urgently required and one such method (community trapping) is herein advocated. Aims To provide baseline information on rodent and shrew communities in agro-ecosystems in three African countries and to demonstrate efficacy of ecologically based rodent management (EBRM) in Africa (e.g. community household trapping). Methods Removal-trapping in a variety of agro-ecological habitats provided accurate small-mammal species lists. Intensive kill-trapping by rural agricultural communities was carried out experimentally where the efforts of communities were scientifically monitored by kill-trapping to measure impact on rodent numbers and the levels of post-harvest damage to stored grains. Key results Our study revealed a high diversity of endemic species in agricultural habitats in Tanzania and Namibia (but not Swaziland) and the existence of undescribed and possibly rare species, some of which may be at risk of extinction from unchecked habitat transformation for agriculture. Treatment-control studies showed that communities in three African countries could effectively reduce pest rodent populations and rodent damage by intensive trapping on a daily basis in and around the community. Conclusions Community trapping reduced pest rodent populations and damage to stored grains. Unlike the use of indiscriminate rodenticide, this practice is expected to have a negligible effect on beneficial non-target rodent and shrew species. Implications Ecologically based rodent management approaches such as community trapping will conserve beneficial non-pest rodent communities and ultimately improve crop protection. [ABSTRACT FROM AUTHOR]

Context: The multimammate mouse, Mastomys natalensis (Smith, 1834), is an important agricultural pest in southern and eastern Africa where it can cause significant crop losses. Mastomys natalensis is known to consume a variety of food in response to the availability of food items. However, it is currently unknown whether maize crop growth stages affect the spatio-temporal diet of this species. Aims: We examined the foods consumed by M. natalensis in different habitats and seasons in central Tanzania and Swaziland. Methods: Diet was investigated in Tanzania in four different habitats (woodland, vegetable gardens, maize fields and fallow land) during different maize crop growth stages between March 2008 and February 2009. In Swaziland, this was conducted in three habitats (fallow land, cultivated fields and pristine land) during three crop growth stages (pre-planting, vegetative stage and post-harvest) between March 2008 and April 2009. Micro-histological examination of undigested fragments from the stomachs of trapped animals was made whereby the preserved stomach content was placed in a Petri dish and sorted using a 25× or 50× magnification binocular stereoscope. Stomach contents were identified as: grain and/or seeds (both grasses and maize), plant material (roots, stems and leaves), invertebrates, pods of seeds, fruits (vegetable fruit such as tomato), animal hairs and unidentified matter. If necessary, a lugol solution was used to determine the presence of starch for maize and grass seeds or grains. Key results: In both countries, grain predominated in the diet of M. natalensis. Statistical analyses showed that there were no differences due to seasons or habitats. Therefore, the percentage volume and relative importance were the same across habitats and seasons in both countries. Conclusions: Our findings highlight clearly that M. natalensis is a generalist species feeding on available resources depending on the season and the habitat. Its preference for grain may account for its abundance in maize plantations and confirms it as one of the major pests in crop plantations, especially grain. Implications: This information offers a useful tool for determining the pest status in different habitats and/or seasons. The findings of this study have implications for agriculture and conservation. [ABSTRACT FROM AUTHOR]

Context: Rodent pests can have severe impacts on crop production in sub-Saharan Africa. In particular, the multimammate mouse Mastomys natalensis severely damages agricultural crops in southern and eastern Africa, leading to significant losses. Both its population ecology and breeding biology have been studied in agricultural and natural habitats. Population numbers erupt depending on the timing and amount of rainfall and may reach plague proportions, especially in agricultural settings, where it may become a serious pest. However, the ecology of this species, in particular its interactions with other species within the context of human settlement, is poorly understood. It may occasionally enter houses, but the degree to which it does so and the factors influencing this movement are not known. Aims: We investigated the relationship between Rattus spp. and M. natalensis entering buildings in an agro-ecological setting. We predicted that M. natalensis would enter houses more readily when food availability was lowest in the surrounding fields, and when the larger Rattus spp. were absent. Methods: We followed 40 individuals of M. natalensis in Swaziland and Namibia by radio-telemetry. Mice were captured in maize fields within 50 m of a homestead and fitted with radio-transmitters at three different times corresponding to different stages of crop development: pre-harvest, post-harvest and pre-planting. To corroborate the findings of the telemetry study, a non-toxic marker, rhodamine B, was mixed with standard bait and left at bait stations inside houses in 10 homesteads in Swaziland and Tanzania. Key results: Mice remained in the fields during the entire period of study in Swaziland, but entered buildings in Namibia during the post-harvest stage, which may represent a period of food shortage for these mice in the field. Rodents captured after baiting with rhodamine B demonstrated that Rattus spp. predominated within the houses. A small number of rhodamine B-marked M. natalensis were captured outside the houses, the proportion declining with distance away from the houses. Conclusions: These results suggest that in a typical rural African setting dominated by subsistence agriculture, Rattus spp. (when present) competitively exclude the smaller M. natalensis from entering houses. Implications: Interactions between rodent pest species may be important in determining which rodent species enter houses in rural African landscapes. Consideration of such interactions may play an important role when developing pest management strategies. [ABSTRACT FROM AUTHOR]

Rodent management in agriculture remains a major challenge in developing countries where resource-poor farmers are ill equipped to deal with pest species. It is compounded by unpredictable outbreaks, late control actions, lack of/or inadequate expert interventions, expensive rodenticides and other factors. Ecologically based rodent management (EBRM) is recommended as the way forward for rodent management in Africa. EBRM relies on understanding the ecology of pest species and formulating this knowledge into management programs. The present paper evaluates the potential for establishing EBRM in Africa and the challenges that have to be overcome to implement it. The major constraints for establishing EBRM in Africa include the absence of key studies on the taxonomy and ecology of rodents, inadequate research on EBRM, lack of knowledge by farmers on available technologies and agricultural policies that are unfavourable. The development of EBRM and its success in Asia is a strong encouragement to African scientists to develop similar management strategies for the most important pest species such as the multimammate rats, Mastomys natalensis. EBRM initiatives such as the Development of Ecologically Based Rodent Management for the Southern Africa Region (ECORAT) project undertook studies on e.g. rodent ecology, taxonomy, knowledge, attitude and practices and rodent-human interactions in rural agricultural communities. Through this project, EBRM interventions were introduced in Tanzania, Swaziland and Namibia to provide solutions to local rodent-pest problems. Intervention actions including community-based intensive trapping of rodents, habitat manipulation and sanitary measures demonstrated that the impacts of rodents on communities could be drastically reduced. EBRM programs in Africa must address how to change attitudes of target communities, building scientific capacity, implanting rodent-management skills by translating the developed technologies and strategies into simple understandable and easy-to-implement actions and influencing policy makers to accept the concepts and practices to be introduced. Further, we need to demonstrate that EBRM is economically feasible and sustainable and that through community participation, EBRM will become deeply rooted in those communities. [ABSTRACT FROM AUTHOR]