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Rapid chromosomal evolution in the mesic four-striped grass rat rhabdomys dilectus (rodentia, muridae) revealed by mtDNA phylogeographic analysis
(Blackwell Verlag GmbH, 2011-04-27) Castiglia, Riccardo; Solano, Emanuela; Makundi, Rhodes H.; Hulselmans, Jan; Verheyen, Erik; Colangelo, Paolo
The mesic four-striped grass rat Rhabdomys dilectus De Winton, 1897 is distributed in mesic regions of southern and eastern Africa. We carried out a molecular and chromosomal study of the northernmost populations of the species to provide insight into the subspecific boundaries identified within the species and to describe its genetic structure in Eastern Africa. Maximum likelihood, maximum parsimony and neighbour- joining methods were used to construct phylogenetic relationships among all the haplotypes belonging to the large part of the species range. Times of divergences were estimated assuming a relaxed molecular clock with two calibration points. We identified three well-supported clades within R. dilectus. One basal clade corresponding to Rhabdomys d. chakae (2n = 48) is found in South Africa. Two additional sister clades corresponding to R. d. dilectus (2n = 48 and 2n = 46) are allopatrically distributed in southern and northern parts of the species range. Genetic divergence among the three clades is relatively high (ranges 4.2–5.7%). A very divergent new karyotype 2n = 38, FNa = 60 was found in two high-altitude populations on Mt. Meru and Mt. Kilimanjaro. The karyotype differences consist in three Robertsonian fusions and one whole-arm reciprocal translocation. Interestingly, the mtDNA phylogeny does not match with the diploid numbers. In fact, the 2n = 38 specimens form a monophyletic group within a clade that includes specimens with the 2n = 46 karyotype that appears as paraphyletic. We estimated the new karyotype originated in peripatric condition during the last phases of the Pleistocene. This study confirms the importance of chromosomal analysis in detecting taxonomic units and cryptic diversity in rodents.
Influence of vegetation structure, seasonality, and soil properties on rodent diversi community assemblages in west Mount Kilimanjaro, Tanzania
(John Wiley & Sons Ltd., 2022-07-22) Thomas, Suzana M.; Soka, Geofrey E.; Mulungu, Loth S.
Rodent diversity and community assemblages are affected by several biotic and abiotic factors such as vegetation structure and seasonality. Vegetation structure particularly ground cover influences rodent diversity and community assemblages through provision of food resources and protection from predators. Such informa- tion is important for understanding species–habitat relationships for management and conservation. This study was conducted to determine the influence of vegetation structure, seasonality, and soil properties on species richness, abundance, commu- nity assemblages, and habitat association of rodents in west Mt Kilimanjaro. Rodent trapping was conducted using removal and capture–mark–recapture (CMR) methods with medium-sized Sherman's live traps, snap, and Havarhart traps. Rodents were trapped during wet and dry seasons for three consecutive nights at 4 weeks intervals from April 2020 to March 2021. Environmental variables including vegetation struc- ture, soil physical properties, and disturbance levels were recorded for each habitat type. Fourteen species of rodents were trapped in 25,956 trap nights. Rhabdomys pumilio, Praomys delectorum, and Lophuromys verhageni were the most dominant spe- cies across all habitats and seasons. L.verhageni occurred in all habitats while R.pumilio was restricted from occurring in montane forests. Moreover, species richness and abundance were influenced by habitat types, seasonality, soil type, and ground cover. Generally, both species richness and abundance were higher in fallows and montane forests and significantly lower in plantation forest and agricultural fields. In addition, rodent diversity was highest in fallows, followed by montane forests, and lowest in agricultural fields. Furthermore, rodents were associated with habitat types and veg- etation structure forming two major community assemblages that significantly dif- fered between habitats. Our study conclude that, community assemblages of rodents on Mt. Kilimanjaro were affected by functional spatial heterogeneity of the habitats occupied. Therefore, use of different habitats by rodents may be indicative of the landscape integrity and ecosystem changes based on species assemblages
Density dependence and persistence of Morogoro arenavirus transmission in a fluctuating population of its reservoir host
(British Ecological Society, 2019-07-21) Mariën, Joachim; Borremans, Benny; Verhaeren, Christophe; Kirkpatrick, Lucinda; Gryseels, Sophie; Bellocq, Joëlle Goüy de; Günther, Stephan; Sabuni, Christopher A.; Massawe, Apia W.; Reijniers, Jonas; Leirs, Herwig
A key aim in wildlife disease ecology is to understand how host and parasite characteristics influence parasite transmission and persistence. Variation in host population density can have strong impacts on transmission and outbreaks, and theory predicts particular transmission–density patterns depending on how para- sites are transmitted between individuals. Here, we present the results of a study on the dynamics of Morogoro arenavirus in a population of multimammate mice (Mastomys natalensis). This widespread African rodent, which is also the reservoir host of Lassa arenavirus in West Africa, is known for its strong seasonal density fluctuations driven by food availability. We investigated to what degree virus transmission changes with host population density and how the virus might be able to persist during periods of low host density.A seven‐year capture–mark–recapture study was conducted in Tanzania where rodents were trapped monthly and screened for the presence of antibodies against Morogoro virus. Observed seasonal seroprevalence patterns were com- pared with those generated by mathematical transmission models to test different hypotheses regarding the degree of density dependence and the role of chroni- cally infected individuals. We observed that Morogoro virus seroprevalence correlates positively with host density with a lag of 1–4 months. Model results suggest that the observed sea- sonal seroprevalence dynamics can be best explained by a combination of verti- cal and horizontal transmission and that a small number of animals need to be infected chronically to ensure viral persistence. Transmission dynamics and viral persistence were best explained by the existence of both acutely and chronically infected individuals and by seasonally changing transmission rates. Due to the presence of chronically infected rodents, rodent control is unlikely to be a feasible approach for eliminating arenaviruses such as Lassa virus from Mastomys populations.
Leptospira seropositivity in humans, livestock and wild animals in a semi-arid area of Tanzania
(MDPI, 2021-06-03) Mgode, Georgies F.; Mhamphi, Ginethon G.; Massawe, Apia W.; Machang’u, Robert S.
Background: Leptospirosis is among the major neglected zoonoses in developing countries. The prevalence of leptospirosis remains underestimated in many African countries because of limited diagnostic facilities. We studied Leptospira seropositivity prevalence in humans, sheep, goats and rodents in a semi-arid region of central Tanzania and compared findings with reports from humid tropical areas. The aims were to establish the disease burden in different settings; understand circulat- ing Leptospira serovars and potential major reservoirs for establishing appropriate control measures. Methods: Humans, sheep, goats, rodents and shrews (insectivores) were sampled from Bahi district, a semi-arid area in central Tanzania. Samples were tested for leptospiral antibodies using microscopic agglutination test (MAT) consisting of Leptospira serovars mainly reported in Tanzania and reference strains. Findings were compared with previous data to determine the disease epidemiological pat- terns. Results and conclusion: Semi-arid area showed high Leptospira seropositivity prevalence in humans and domestic animals due to intensive human–animal interactions at scarce water points and by flash flooding which occur in the area. Rodent population in the semi-arid areas was relatively low due to flooding. Leptospira seropositivity in rodents was also slightly lower, and the rodents appeared to be prolific breeders, probably as a means to compensate for the lost population during extreme drought as well as during short spells of floods. Intensive human–animal interaction in the semi-arid areas especially, in water sources in valleys where human and animals often meet, likely increased the risk of leptospirosis transmission to rice farmers in the area. Goats and sheep which are kept around homesteads had higher leptospiral antibodies prevalence (62%), nearly double of the 38% reported in same species in humid tropical regions of Tanzania. Livestock, especially goats and sheep, could be the major source of leptospirosis transmission to humans. Vaccination of livestock with vaccines against local Leptospira strains should be encouraged, and rodent control emphasized, as part of a management strategy against leptospirosis. Public awareness of leptospirosis must also be raised and supported by availability of rapid test kits in clinics for preliminary testing of leptospirosis in people with fevers of unknown origin.
ProxLogs: Miniaturised proximity loggers for monitoring association behaviour in small mammals
(Hystrix, the Italian Journal of Mammalogy, 2021) Kirkpatrick, Lucinda; Olivares, Ivan Hererra; Massawe, Apia; Sabuni, Christopher; Leirs, Herwig; Berkvens, Rafael; Weyn, Maarten
The ability to monitor associations between wild animals is essential for understanding the processes governing gene transfer, information transfer, competition, predation and disease transmission. Until recently, such insights have been confined to large, visible or captive animals. However, the rapid development of miniature sensors for consumer electronics is allowing ecologists to monitor the natural world in ways previously considered impossible. Here we describe miniature (<1g) proximity loggers we have developed that use Bluetooth Low Energy transmission to register contacts between individuals. Our loggers are open source, low cost, rechargeable, able to store up to 2000 contacts, can be programmed in situ and can download data remotely or through a mobile phone application, increasing their utility in remote areas or with species which are challenging to recapture. We successfully trialled our loggers in a range of field realistic conditions, demonstrating that Bluetooth Low Energy is capable of logging associations in structurally complex habitats, and that changes in received signal strength can be equated to short range changes in distance between loggers. Furthermore, we tested the system on starlings (Sturnidae vulgaris).
A comparative assessment on rodent impacts and cultural perceptions of ecologically based rodent management in three Afro-Malagasy farming regions
(International Society of Zoological Sciences, 2020) Constant, Natasha Louise; Swanepoel, Lourens; Williams, Samual T.; Soarimalala, Voahangy; Goodman, Steven M.; Massawe,Apia T.; Mulungu, Loth S.; Makundi, Rhodes H.; Mdangi, Mashaka E.; Taylor, Peter John; Belmain, Steven R.
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 three 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 groups 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 favour 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
Ecologically based rodent management in Africa: potential and challenges
(CSIRO, 2011) Makundi, Rhodes H.; Massawe, Apia W.
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.
Relationship between population density and viral infection: a role for personality?
(Wiley, 2019) Broecke, Bram Vanden; Mariën, Joachim; Sabuni, Christopher Andrew; Mnyone, Ladslaus; Massawe, Apia W.; Matthysen, Erik; Leirs, Herwig
Conspecific density and animal personality (consistent among‐individual differences in behavior) may both play an important role in disease ecology. Nevertheless, both factors have rarely been studied together but may provide insightful information in understanding pathogen transmission dynamics. In this study, we investigated how both personality and density affect viral infections both direct and indirectly, using the multimammate mice (Mastomys natalensis) and Morogoro arenavirus (MORV) as a model system. Using a replicated semi‐natural experiment, we found a positive correlation between MORV antibody presence and density, suggesting that MORV infection is density‐dependent. Surprisingly, slower explorers were more likely to have antibodies against MORV compared to highly explorative individuals. However, exploration was positively correlated with density which may suggest a negative, indirect effect of density on MORV infection. We have shown here that in order to better understand disease ecology, both personality and density should be taken into account.
Malaria prevalence in asymptomatic and symptomatic children in Kiwangwa, Bagamoyo district, Tanzania
(Malaria Journal, 2017) Sumari, Deborah; Mwingira, Felista; Selemani, Majige; Mugasa, Joseph; Mugittu, Kefas; Gwakisa, Paul
Malaria prevalence continues to decline across sub-Saharan Africa as a result of various intervention strategies. However, the diseases still poses a public health concern in the region. While symptomatic malaria is recog- nized and treated, asymptomatic infections become increasingly important for interrupting transmission. A cross-sec- tional survey was conducted to assess malaria prevalence in symptomatic and asymptomatic children in Kiwangwa ward in Bagamoyo District in Tanzania. Methods: Four hundred school-aged children in Kiwanga ward were recruited in the study; 200 from Kiwangwa dispensary and 200 from nearby schools. Primary health parameters were examined and blood samples collected and examined for Plasmodium falciparum prevalence using rapid diagnostic test (RDT), light microscopy (LM) and reverse transcription quantitative PCR (RT-qPCR) targeting transcripts of A-type 18s rRNA of P. falciparum. Gametocytes were detected by LM and RT-qPCR targeting transcripts of gametocyte specific marker, Pfs25. Results: Overall P. falciparum prevalence was 73.3, 40.8 and 36.3% by RT-qPCR, RDT and LM in the study area, respec- tively (P < 0.001). As expected symptomatic children had a significantly higher prevalence of 89, 67.5 and 64.5% by qPCR, RDT and LM, compared to 57.5, 14 and 8% in the asymptomatic group, respectively. However, gametocyte prevalence in asymptomatic individuals was higher by both LM (2%) and qPCR (14%) than in symptomatic individuals LM (0.5%) and qPCR (3%). Conclusions: A substantial difference in prevalence of symptomatic and asymptomatic infections observed in Kiwangwa ward underpins the use of molecular tools in malaria surveillance aiming at estimating prevalence and transmission. Notably, the higher gametocytaemia observed in asymptomatic children indicates the reservoir infec- tions and points to the need for detection and treatment of both asymptomatic and symptomatic malaria.
Antifungal effect of a local bacillus subtilis, isolate TM07, on Fusarium oxysporum f.sp. Lycopersici in Morogoro, Tanzania
(Tanzania Journal of Agricultural Sciences, 2021) Machang’u, R; Maerere, A.; Mwinuka, B; Nashon, J; Makingi, G
Fusarium oxyporum f.sp. lycopersici causes tomato wilt, a severe disease that leads to extensive yield and quality loss of tomatoes in Tanzania. Management of Fusarium infection is particularly challenging given the health and environmental concerns over continued use of chemical pesticides on horticultural food crops. However, there is an increasing focus towards the use of biocontrol agents to combat phytopathogens worldwide. In this study, bacterial isolates from tomato rhizosphere were screened for their antagonistic activity in vitro on F. oxysporum. Based on its superior effectiveness, one isolate, designated TM07, was selected and characterized as Bacillus subtilis by morphological, biochemical and molecular procedures. On potato dextrose agar (PDA) the isolate showed an appreciable degree of radial growth inhibition (RGI) of 40.5% of the Fusarium, compared to control (55.9%). Further investigations are recommended to elucidate on the mechanism behind the inhibitory effect of isolate TM07. In vivo studies are also recommended to assess the possibility of applying the B. subtilis, isolate TM07, as a local biocontrol agent of Fusarium wilt of tomato and other susceptible crops.
Mice, rats, and people: the bio-economics of agricultural rodent pests
(The Ecological Society of America, 2003) Stenseth, Nils Chr; Leirs, Herwig; Skonhoft, Anders; Davis, Stephen A; Pech, Roger P; Andreassen, Harry P; Singleton, Grant R; Lima, Mauricio; Machang’u, Robert S; Makundi, Rhodes H; Zhang, Zhibin; Brown, Peter R; Shi, Dazhao; Wan, Xinrong
Mice, rats, and other rodents threaten food production and act as reservoirs for disease throughout the world. In Asia alone, the rice loss every year caused by rodents could feed about 200 million people. Damage to crops in Africa and South America is equally dramatic. Rodent control often comes too late, is inefficient, or is considered too expensive. Using the multimammate mouse (Mastomys natalensis) in Tanzania and the house mouse (Mus domesticus) in southeastern Australia as primary case studies, we demonstrate how ecology and economics can be combined to identify management strategies to make rodent control work more efficiently than it does today. Three more rodent–pest systems – including two from Asia, the rice-field rat (Rattus argentiventer) and Brandt's vole (Microtus brandti), and one from South America, the leaf-eared mouse (Phyllotis darwini) – are presented within the same bio-economic perspective. For all these species, the ability to relate outbreaks to interannual climatic variability creates the potential to assess the economic benefits of forecasting rodent outbreaks
Arenavirus dynamics in experimentally and naturally infected rodents
(EcoHealth Alliance, 2017-06) Marien, Joachim; Borremans, Benny; Gryseels, Sophie; Broecke, Bram Vanden; Becker-Ziaja, Beate; Makundi, Rhodes; Massawe, Apia; Reijniers, Jonas; Leirs, Herwig
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.
African centre of excellence for innovative rodent pest management and biosensor technology development (ACE IRPM and BTD- Rat-Tech)
(2016-10) Makundi, R. H; Massawe, A.W
Rodents are some of the most serious mammalian pests the world over. However, their economic and social impact is not quantified in Sub-Saharan Africa. Moreover, while some of the zoonotic diseases attributed to rodents such as Lassa fever and bubonic plague are endemic in rural Africa, occasionally leading to serious outbreaks, more often than not, rodent-borne diseases are not recognized, and hence are inadequately managed. The African Centre of Excellence (ACE) in Innovative Rodent Pest Management and Biosensor Technology Development (IRPM and BTD) will enhance scientific knowledge, Technology and Innovation (STI) on Rodent Pest Management in Africa. The IRPM and BTD activities will incorporate biosensor technology using trained rats for land mine detection and support their operational deployment to complement existing technologies to free mine afflicted lands in Africa and elsewhere and release these for safe use by humans (settlement, agriculture, mining, livestock, etc.). Novel diagnostic approaches are a key component to tackling Tuberculosis epidemic, yet in resource-limited settings in Africa, the latest advanced diagnostic technologies are lacking. Trained rats are efficient and reliable TB diagnostic biosensor technology. The ACE for IRPM and BTD will build capacity through training at the MSc and PhD levels in rodent taxonomy, ecology, innovative STI in rodent management and biosensor technology. IRPM and BTD will establish basic and applied research programs for African scientists to pursue high-impact projects in rodent management, understanding the impact of zoonotic diseases on communities and their mitigation, and how best to use biosensor technology for detecting landmines and diagnosis of diseases. A minimum of 60 Master of Science and 32 PhD students will be trained and faculty exchange between regional higher education institutions will be supported. Short courses will be conducted focusing on dissemination of sustainable STI solutions to rodent problems in Africa. Research will be focused to solve regional rodent problems that impact on rural communities in Africa.
Jigger flea infestation (tungiasis) in rural western Tanzania: high prevalence and severe morbidity
(Elsevier, 2011-12) Mazigo, H.D; Bahemana, E; Konje, E.T; Dyegura, O; Mnyone, L.L; Kweka, E.J; Kidenya, B.R; Heukelbach, J
Epidemiologic and clinical data on the parasitic skin disease tungiasis are limited from sub-Saharan Africa, and virtually nonexistent from the East African region. We performed a community-based cross-sectional study in two villages in Kasulu district, western Tanzania. Study participants were examined for the presence of tungiasis and disease-associated morbidity. In total, 586 individuals >5 years of age were enrolled, and 249 (42.5%; 95% CI: 38.5-46.5) diagnosed with tungiasis. The ≥45 year-olds showed highest prevalence of tungiasis (71.1%) and most severe parasite load (median number of embedded fleas: 17.5; interquartile range: 15-22.5). Prevalence was slightly, but not significantly, higher in males than in females (45.3 vs 39.7%; p=0.17). Itching (68.3%), pain (38.6%) and ulcers (30.1%) were common; 22.1% of individuals found it difficult to walk due to tungiasis, and in 21.3% loss of toenails was observed. Considering the high prevalence and considerable morbidity in the population, we conclude that tungiasis is a public health threat in the study villages and that the disease needs to be recognized by health authorities. Future studies on risk factors, animal reservoirs and evidence-based control measures are needed.
Quantitative analysis of risk factors associated with brucellosis in livestock in the Katavi-Rukwa ecosystem, Tanzania
(Springer.com, 2015-11-12) Assenga, J A; Matemba, E L; Malakalinga, J J; Muller, S K; Kazwala, R R
t Brucellosis is a neglected contagious bacterial diseaseofpublichealthand economicimportance.Nevertheless, its spread is not well known to many livestock farmers. Unmatched case control study was carried out to identify risk factors associated with brucellosis in cattle and goats at the herd level in Mpanda, Mlele and Nsimbo districts of Katavi region, in Tanzania between September 2012 and July 2013. A total of 138 adult respondents were selected randomly for the interview using a structured questionnaire. The criterion forinclusionwastohaveatleastoneBrucella-positiveanimal intheherdwhilethecontrolwaschosenfromamongtheherds whichtheseanimalstestednegative.Thepresenceofseropositive herds were statistically linked (P<0.1) by univariate analysis with such variables as lack of formal education amongtheherders;slaughteringofcattleorgoatsinthehousehold;thehistoryofoccurrenceofabortionintheherd;andthe historyofoccurrenceofretainedfoetalmembranesintheherd following parturition. However, in the multivariate analysis, lack of formal education among the herders and the previous history of occurrence of retained foetal membrane in the herd following parturition were significantly associated with Brucella seropositive (P<0.05). This study suggests the need forraisingcommunityawarenessontheriskfactorsassociated with the transmission of brucellosis between animals and humans and the implementation of disease prevention and control programmes.
Relationship between sampling intensity and precision for estimating damage to maize caused by rodents
(Blackwell Publishing and IOZ/CAS, 2007) Mulungu, Loth S.; Massawe, Apia W.; Makundi, Rhodes H.; Leirs, Herwing
In this study we aimed to determine the relationship between sampling intensity and precision for estimating rodent damage. We used the systematic row sampling technique to provide data to achieve precision and accuracy in estimations of rodent damage in maize fields at the planting and seedling stages. The actual rodent damage to maize in 15 fields, each 0.5 ha in size, in Morogoro, Tanzania, was established at the seedling stage. These data were used to simulate the sampling intensities that would provide precision and accuracy. The variations between estimates were plotted against the sampling intervals. The results of this study show that the relationship between average standardized variances and sampling intervals is linear. The heterogeneous distribution of damage in some plots caused variations in the accuracy of the estimates between plots, but a sampling interval of five rows consistently produced estimates with a variance of less than 10%. We provide a standard curve that will allow a decision to be made on the sampling intensity as a function of required precision using the systematic row sampling technique in maize fields. Key words: rodents, sampling interval, simulation, standard curve, systematic row sampling.
Impact of spatio-temporal simulations of rat damageon yield of rice (Oryza sativa L.) and implications forrodent pest management
(Taylor & Francis Group, 2014-11) Mulungu, L, S.; Lagwen, P, P.; Mdangi, M, E.; Kilonzo, B, S.; Belmain, S, R.
Rodents often damage crops throughout the growing season, from germination to harvest, thus making it difficult tounderstand the cumulative effects of rodent damage for crops such as rice that are able to partially compensate for damage.Compensation can make it difficult to understand the impact of variable rodent damage in terms of when the damageoccurs, its severity and thus when, whether and how rodent pests should be controlled. The compensatory responses of riceto simulated rat damage carried out at different growth stages and at different spatial levels of severity showed that higheryield was recorded during the wet season in comparison to the dry season. However, yield loss was observed during allcropping stages for all levels of simulated damage for wet and dry season crops, with significant compensation noted at thetransplanting [14 days after sowing (DAS)] and vegetative (45 DAS) stages. Only damage at the maturity (110 DAS) stageresulted in significant reductions in rice crop yield. Seasonal differences suggest water availability was an important factorthat perhaps enhanced rice production. The ability of rice to compensate for early rodent damage could potentially reducea farmer’s perception of damage. However, failing to control rodents at these earlier crop growth stages could lead toincreased rodent populations at the time of maturity when compensatory effects are limited.
Population dynamics and breeding patterns of multimammate mouse,Mastomys natalensis (Smith1834),inirrigatedriceﬁeldsinEastern Tanzania
(Willey Online Library, 2012-06-21) Mulungu, L S; Ngowo, V; Mdangi, M; Katakweba, A S; Tesha, P; Mrosso, P F; Mchomvu, M; Sheyo, P M; Kilonzo, B S
Multimammate mice are the most important vertebrate pests in Sub-Saharan Africa and are also reservoirs of many zoonotic diseases, including sylvan plague. This study investigated the population dynamics and breeding patterns of this mouse in irrigated rice croppings ystems in easternTanzania. RESULTS:The multimammate mouse,Mastomys natalensis,population varied with habit at nd months.Fallow land had a more abundant population than rice ﬁelds. The highest population peak was observed during the dry season from July to October. Mastomysnatalensis is sexually active throughout the year in the study area, although it reaches the highest level in June and December when rice is at the maturity stage. This suggests that breeding is highly inﬂuenced by the presence of a rice crop in both seasons. More juvenile individuals were recorded in August and September, indicating that they were produced in the previous breeding months. The sex ratio of M.natalensis was not skewed to either males or females, indicating that it was at parity. CONCLUSION: Rodent population dynamics during the study periods in all habitats indicated that high birth rates accounted for the rapid population growth and turnover. Regular control and sustainable operations are thus essential if rodent pest populations are to be kept within tolerablel imits.
Population dynamics and breeding patterns of Multi-mammate mouse, Mastomys natalensis (Smith 1834) in irrigated rice field in Eastern Tanzania
(Wiley Online Library, 2012-06-21) Mulungu, Loth; Ngowo, Victoria; Mdangi, Mashaka; Katakweba, Abdul; Tesha, Protas; Mrosso, Furaha; Mchomvu, Mary; Sheyoe, Paul; Kilonzo, Bukhet
BACKGROUND: Multimammate mice are the most important vertebrate pests in Sub-Saharan Africa and are also reservoirs of many zoonotic diseases, including sylvan plague. This study investigated the population dynamics and breeding patterns of this mouse in irrigated rice cropping systems in eastern Tanzania. RESULTS:Themultimammatemouse,Mastomysnatalensis,populationvariedwithhabitatandmonths.Fallowlandhadamore abundant population than rice ﬁelds. The highest population peak was observed during the dry season from July to October. Mastomys natalensis is sexually active throughout the year in the study area, although it reaches the highest level in June and December when rice is at the maturity stage. This suggests that breeding is highly inﬂuenced by the presence of a rice crop in both seasons. More juvenile individuals were recorded in August and September, indicating that they were produced in the previous breeding months. The sex ratio of M.natalensis was not skewed to either males or females, indicating that it was at parity. CONCLUSION: Rodent population dynamics during the study periods in all habitats indicated that high birth rates accounted for the rapid population growth and turnover. Regular control and sustainable operations are thus essential if rodent pest populations are to be kept with intolerable limits.
Pattern of ovulation in an ancient, solitary mole-rat lineage: Heliophobius argenteocinereus emini from Tanzania
(CORNELL UNIVERSITY, 2017) Katandukila, J. V.; Ngalameno, M. K.; Mgode, G. F.; Bastos, A. D. S.; Bennett, N. C.
Heliophobius is an ancient subterranean rodent lineage within the family Bathyergidae, that displays seasonal breeding over a broad geographical range. In East Africa, reproduction in these solitary mole-rats has been shown to coincide with the long rains, but it is not clear whether Heliophobius argenteocinereus emini (Noack 1894) from Tanzania is an induced or spontaneous ovulator. To address this, urinary progesterone was measured every second day over a period of 132 days in six wild-caught females subjected to three sequential experimental treatments. In the first, control (C) treatment, females were housed singly for a period of 44 days, following which non-physical contact (NPC) with a vasectomised male and then physical contact (PC) with the same vasectomised male, occurred, in each of the subsequent 44-day treatments. Non-invasive monitoring of ovarian cyclicity confirmed that mean urinary progesterone concentration was higher during PC than during either NPC or C, despite the fact that the males were vasectomised and incapable of fertilising the females. Examination of penile morphology revealed that males possess epidermal projections on the glans penis which probably bring about cervical stimulation during coitus. These findings together with the female progesterone profiles imply the species is an induced ovulator stimulated by penile intromission.

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