Trap Barrier System (TBS) as a New Tool for Rodent Pest Management in Irrigated Rice in Africa

Rodent infestation poses a serious threat to smallholder farmers in both developed and developing countries where a large proportion of potential crop yield is lost. In Tanzania, the average annual yield loss of rice is estimated to be around 5–12%. Management of rodent pests in Africa relies mostly on the use of rodenticides which, however, are often applied only when damage has already occurred rather than routinely. Rodenticides used in this way are rarely economically and ecologically sustainable for managing rodents in irrigated rice. A “community-based Trap-Barrier-System (cTBS)” provides an alternative novel rodent control approach for controlling rodents in rice fields. This is basically a system where rodents are trapped in a rice field that is planted a short period earlier than the surrounding fields and therefore attracting rodents from a much wider area than the field itself. The system has proved very successful in irrigated rice fields in Tanzania, increasing rice yields in the intervention fields by 40.91%. A single cTBS can confer protection in up to 16 ha of irrigated rice field. Therefore, if scaled up and used widely, TBS has a great potential for managing rodent pests and improving yield in irrigated rice fields

A Decade-Long Change in the Elevational Distribution of Non-Volant Small Mammals on Mount Meru, Tanzania

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

Ecological Biogeography of West Usambara Mountains: A Study on the Influence of Abiotic Factors to Spatial Distribution of Plant and Animal Species

West Usambara Mountains, Tanzania are famous for rich biodiversity and endemic species of plants and animals. Although there have been extensive studies on plant and animals species, little attention has been given on abiotic factors influencing their spatial distribution. Given rampant degradation of vegetation and associated consequence on biodiversity, knowledge on abiotic factors influencing distribution of species along the landscape become pertinent for conservation. A study was carried out to explore abiotic factors impacting plant and animals species distribution. Soil, landform and land use/cover were studied using grids of 20 m × 20 m using FAO Guidelines for Soil Profile and Habitat Descriptions. Soils were described, sampled for laboratory analysis. Spatial distribution of plant species were determined in the grids, and along the transects, every time estimating the percent cover and describing the habitat. Distribution of animal species was studied using both small mammals and rodent burrows as proxies. Trapping was done using different traps sizes, checking daily for animal caught, counting and re-trapping. Rodent burrows were estimated in same grids by examining a width of 0.5 m from end to end of grid and total number of burrows recorded. Determination of species distribution was done using GLM regression. Results show that species are influenced by elevation, which was common to both plants and animals. Topsoil soil depth was positive to plant species whereas hillshade, surface stones, cultivation and atmospheric temperature were negatively influencing plant species. Rock outcrops, surface stones and cultivation were positively influencing small mammals distribution. It is concluded that factors influencing distribution of small mammals are elevation, surface stones, rock outcrop and cultivation. Factors influencing plant species are elevation soil depth whereas cultivation, hillshade, surface stone and rock out crops negatively impact distribution. For conservation, it is recommended that the best steps are to stop human activities leading to depletion of plant species and accelerating soil erosion and allow for self-regeneration. Control of soil erosion strongly recommended as way of plant species re-establishment

Spatio-temporal patterns in the distribution of the multi-mammate mouse, Mastomys natalensis, in rice crop and fallow land habitats in Tanzania

An understanding of the dispersion patterns of a pest is an important pre-requisite for developing an effective management programme for the pest. In this study, rodents were trapped in two rice fields and two fallow fields for three consecutive nights each month from June 2010 to May 2012. Mastomys natalensis was the most abundant rodent pest species in the study area, accounting for > 95% of the trapped rodent community. Rattus rattus, Dasymys incomtus, Acomys spinosissimus and Grammomys dolichurus comprised relatively small proportions of the trapped population. Morisita’s index of dispersion was used to measure the relative dispersal pattern aggregate, random, uniform) of individuals across each trapping grid as a means of comparing rodent distribution in rice and fallow fields over time. This analysis revealed that the rodents in rice fields generally exhibited an aggregated spatio-temporal distribution. However, the rodents in fallow fields were generally less aggregated, approaching a random distribution in some habitats and seasons. Heat maps of trapping grids visually confirmed these dispersal patterns, indicating the clumped or random nature of captured rodents. ANOVA showed that the parameters of habitat (rice, fallow), crop stage (transplanting, vegetative, booting, maturity) and cropping season (wet, dry) all significantly impacted the number of rodents captured, with the vegetative, dry season, fallow habitat having the highest number of rodents; and the transplanting, wet season, rice habitat with the least number of rodents. Therefore, such spatio-temporal patterns can serve as a tool for developing stratified biodiversity sampling plans for small mammals and decision making for rodent pest management strategies

Leptospira Serovars for Diagnosis of Leptospirosis in Humans and Animals in Africa: Common Leptospira Isolates and Reservoir Hosts

The burden of leptospirosis in humans and animals in Africa is higher than that reported from other parts of the world. However, the disease is not routinely diagnosed in the continent. One of major factors limiting diagnosis is the poor availability of live isolates of locally circulating Leptospira serovars for inclusion in the antigen panel of the gold standard microscopic agglutination test (MAT) for detecting antibodies against leptospirosis. To gain insight in Leptospira serovars and their natural hosts occurring in Tanzania, concomitantly enabling the improvement of the MAT by inclusion of fresh local isolates, a total of 52 Leptospira isolates were obtained from fresh urine and kidney homogenates, collected between 1996 and 2006 from small mammals, cattle and pigs. Isolates were identified by serogrouping, cross agglutination absorption test (CAAT), and molecular typing. Common Leptospira serovars with their respective animal hosts were: Sokoine (cattle and rodents); Kenya (rodents and shrews); Mwogolo (rodents); Lora (rodents); Qunjian (rodent); serogroup Grippotyphosa (cattle); and an unknown serogroup from pigs. Inclusion of local serovars particularly serovar Sokoine in MAT revealed a 10-fold increase in leptospirosis prevalence in Tanzania from 1.9 % to 16.9 % in rodents and 0.26% to 10.75 % in humans. This indicates that local serovars are useful for diagnosis of human and animal leptospirosis in Tanzania and neighbouring countries

Land use determinants of small mammals abundance and distribution in a plague endemic area of Lushoto District, Tanzania

Small mammals are considered to be involved in the transmission cycle of bubonic plague, still occurring in different parts of the world, including the Lushoto district in Tanzania. The objective of this study was to determine the relationship between land use types and practices and small mammal abundance and distribution. A field survey was used to collect data in three landscapes differing in plague incidences. Data collection was done both in the wet season (April-June 2012) and dry season (August-October 2012). Analysis of variance and Boosted Regression Trees (BRT) modelling technique were used to establish the relationship between land use and small mammal abundance and distribution. Significant variations (p ≤ 0.05) of small mammal abundance among land use types were identified. Plantation forest with farming, natural forest and fallow had higher populations of small mammals than the other aggregated land use types. The influence of individual land use types on small mammal abundance level showed that, in both dry and wet seasons, miraba and fallow tended to favour small mammals’ habitation whereas land tillage practices had the opposite effect. In addition, during the wet season crop types such as potato and maize appeared to positively influence the distribution and abundance of small mammals which was attributed to both shelter and food availability. Based on the findings from this study it is recommended that future efforts to predict and map spatial and temporal human plague infection risk at fine scale should consider the role played by land use and associated human activities on small mammal abundance and distribution

Survival and recruitment of the multimammate mouse, Mastomys natalensis (Smith 1834), in a rice agro-ecosystem

We investigated the recruitment and survival of the multimammate mouse, Mastomys natalensis, within irrigated rice and fallow field habitats at different time periods related to rice crop growth stages. Capture-Mark-Recapture data were collected for M . natalensis each month from June 2010 to May 2012, and both recruitment and survival were estimated in relation to land use (irrigated rice or fallow field) within the agro-ecosystem. Higher recruitment and survival were observed in rice fields than in fallow fields suggesting the relationship was compensatory when there was a higher quality food resource. In terms of management, farmers in the study area should implement management strategies in rice fields at both transplanting and maturity stages of crop growth in order to maintain recruitment and survival at low levels

Survival and recruitment of the multimammate mouse, Mastomys natalensis (Smith 1834), in a rice agro-ecosystem

We investigated the recruitment and survival of the multimammate mouse, Mastomys natalensis, within irrigated rice and fallow field habitats at different time periods related to rice crop growth stages. Capture-Mark-Recapture data were collected for M. natalensis each month from June 2010 to May 2012, and both recruitment and survival were estimated in relation to land use (irrigated rice or fallow field) within the agro-ecosystem. Higher recruitment and survival were observed in rice fields than in fallow fields suggesting the relationship was compensatory when there was a higher abundance of food resources. In terms of management, farmers in the study area should implement management strategies in rice fields at both transplanting and maturity stages of crop growth in order to maintain recruitment and survival at low levels.The Zonal Agricultural Research and Development Funds (ZARDEF) through Eastern Zone.http://www.degruyter.com/view/j/mamm2017-03-30am2016Mammal Research InstituteZoology and Entomolog

Relationships between seasonal changes in diet of multimammate rat (Mastomys natalensis) and its breeding patterns in semi-arid areas in Tanzania

The diet and breeding patterns of Mastomys natalensis in semi-arid areas of Isimani division, Iringa region, Tanzania were investigated in maize fields and fallow land. The aim was to investigate the influence of diet on breeding patterns of M. natalensis. Removal trapping was used to capture rodents and analyse diet categories while Capture-mark-release trapping was used to investigate breeding patterns of female M. natalensis. Mastomys natalensis comprised 94%of the total capture, and the remaining 6% comprised of six other species. Statistical analysis of food preferences indicated that both vegetative materials and seeds were significantly higher in the overall diet of M. natalensis compared with other food materials. Significant differences in the proportions of vegetativematerials and seeds were found between seasons (dry, wet), but not between habitats (fallow, maize). There was a clear seasonal pattern in the proportion of reproductively active females with peaks in April and troughs in October. The proportion of vegetative materialswas highest during thewet season and correlated positively with reproductive activity, suggesting that vegetative materials contain certain compounds (e.g. 6-MBOA) that trigger reproductive activity in M. natalensis. The breeding activity of M. natalensis in semi-arid areas might, thus, be reduced by limiting access to fresh vegetative food (e.g. young sprouting grass)

Home ranges, sex ratio and recruitment of the multimammate rat (Mastomys natalensis) in semi-arid areas in Tanzania

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. natalensi