Browsing by Author "Leirs, H."

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The bioeconomics of controlling an African rodent pest species.
(Cambridge University Press., 2006) Skonhoft, A.; Leirs, H.; Andreassen, H. P.; Mulungu, L. S.A.; Stenseth, N. C.
The paper treats the economy of controlling an African pest rodent, the multimammate rat, causingmajor damage in maize production. An ecological population model is presented and used as a basis for the economic analyses carried out at the village level using data from Tanzania. This model incorporates both density-dependent and density-independent (stochastic) factors. Rodents are controlled by applying poison, and the costs are made up of the cost of poison plus the damage to maize production. We analyse how the present-value costs of maize production are affected by various
Comparative and functional morphology of the middle ear in Zambezian mole-rats (Coetomys – Cryptomys, Bathyergidae)
(Belg. J. Zool, 2005-12) Leirs, Herwig; Makundi, Rhodes H.; Davis, Stephen; Lange, Simone; Burda, Hynek; Assogbadjo, A.E.; Codjia, J.T.C.; Sinsin, B.; Ekue, M.R.M.; Mensah, G.A.; Mgode, G.F.; Mhamphi, G.A.; Katakweba, A. W.; Paemelaere, E; Willekens, N.; Leirs, H.; Machang’u, R.S.; Hartskeerl, R.A.
Within the family Bathyergidae, the genus Coetomys (Cryptomys) is the most speciose. However, an unambiguous morphological or morphometrical species diagnosis has not been feasible to date. The middle ear structures involved in sound transmission were examined and measured in six species of Zambezian mole-rats of varying body sizes : Coetomys amatus, C. anselli, C. darlingi, C. kafuensis, C. mechowi and C. whytei. Compari- sons revealed many differences in the shape of the middle ear ossicles allowing species differentiation. Bullar vol- ume, eardrum area and cross-sectional area of the bony meatus were positively correlated with body size (as repre- sented by condylo-basal length) whereas the size of middle ear ossicles was rather independent of body size. Middle ears shared typical features with those found in low-frequency hearing mammals. Contrary to the findings in heter- omyids and the Spalax ehrenbergi species complex, within the genus Coetomys, those species occupying more mesic habitats had more efficient tympano-ossicular systems (suggesting more sensitive hearing) than species from drier habitats.
Cytotaxonomy of rodent species from Ethiopia, Kenya, Tanzania and Zambia
(Belg. J. Zool, 2005) Corti, M.; Castiglia, R.; Colangelo, P.; Capanna, E.; Beolchini, F.; Bekele, A.; Oguge, N. O.; Makundi, R. H.; Sichilima, A. M.; Leirs, H.; Verheyen, W.; Verhagen, R.
An extended survey of taxa belonging to two genera of Cricetomyinae (Cricetomys and Saccostomus), one Gerbillinae (Gerbilliscus), eight Murinae (Acomys, Aethomys, Arvicanthis, Lemniscomys, Mus (Nannomys), Mastomys, Grammomys, Stenocephalemys) and one Myoxidae (Graphiurus) was carried out as part of the EU programme “Staplerat” involving Ethiopia, Kenya, Tanzania and Zambia. Here we report the diploid and autosomal fundamental numbers of these rodent taxa. Seventeen of them were unknown, for four we report chromosomal variants and for another 16 new localities where they occur. We discuss their specific status taking into consideration our results together with data from literature and highlight the problems in taxonomy and systematics that are yet to be solved, due do their extended range and the occurrence of species complexes. We highlight cases for which there should be a re-evaluation of specific names that were not included in the last rodent checklist.
Evaluation of short-, mid- and long-term effects of toe clipping on a wild rodent
(Wildlife Research, 2015) Leirs, H.; Makundi, Rhodes H.; Sluydts, V.; Borremans, B.
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.
Genetic distinction between contiguous urban and rural multimammate mice in Tanzania despite gene flow
(Journal of evolutionary biology., 2016) Gryseels, S.; Goüy de Bellocq, J.; Makundi, R.; Vanmechelen, K.; Broeckhove, J.; Mazoch, V.; Šumbera, R.; Zima Jr, J.; Leirs, H.; Baird, S. J. E.
Special conditions are required for genetic differentiation to arise at a localgeographical scale in the face of gene ﬂow. The Natal multimammatemouse, Mastomys natalensis, is the most widely distributed and abundantrodent in sub-Saharan Africa. A notorious agricultural pest and a naturalhost for many zoonotic diseases, it can live in close proximity to humansand appears to compete with other rodents for the synanthropic niche. Wesurveyed its population genetic structure across a 180-km transect in centralTanzania along which the landscape varied between agricultural land in arural setting and natural woody vegetation, rivers, roads and a city (Moro-goro). We sampled M. natalensis across 10 localities and genotyped 15microsatellite loci from 515 individuals. Hierarchical STRUCTURE analysesshow a K-invariant pattern distinguishing Morogoro suburbs (located in thecentre of the transect) from nine surrounding rural localities. Landscapeconnectivity analyses in Circuitscape and comparison of rainfall patternssuggest that neither geographical isolation nor natural breeding asynchronycould explain the genetic differentiation of the urban population. Using theisolation-with-migration model implemented in IMa2, we inferred that asplit between suburban and rural populations would have occurred recently(<150 years ago) with higher urban effective population density consistentwith an urban source to rural sink of effective migration. The observedgenetic differentiation of urban multimammate mice is striking given theuninterrupted distribution of the animal throughout the landscape and thehigh estimates of effective migration (2NeM = 3.0 and 29.7), suggesting astrong selection gradient across the urban boundary
Genetic structure and diversity of the black and rufous sengi in Tanzanian coastal forests
(Journal of Zoology, 2016) Sabuni, C. A.; Van Houtte, N.; Gryseels, S.; Maganga, S. L. S.; Makundi, Rhodes H.; Leirs, H.; Goüy de Bellocq, J.
The black and rufous sengi Rhynchocyon petersi is restricted to the Eastern ArcMountains and coastal forests of East Africa and considered vulnerable because ofhabitat fragmentation and degradation. Coastal forests are believed to have beenisolated from each other for thousands of years due to climatic changes. SinceR. petersi is described as strongly dependent on its forest habitat, we hypothesizedthat R. petersi from different forests would show genetic divergence. We investi-gated the genetic structure and diversity of this species in four coastal forests inTanzania using eight microsatellites and cytochrome b sequences. In total, 45 indi-viduals were captured after strenuous sampling efforts. For comparative purposeswe also sequenced the cytochrome b of 57 individuals from a sympatric rodent for-est species, Beamys hindei. The results indicate extant R. petersi have descendedfrom a single population of high effective size (Ne) with no forest-distinctive sig-nal. In contrast, B. hindei is more genetically structured: Although the most com-mon haplotype is found in the three closest forests, each forest harbours privatehaplotypes. Moreover, B. hindei Ne appeared 10 times smaller than R. petersi inZaraninge forest. While B. hindei results are consistent with the scenario of long-term isolation of coastal forests, the R. petersi are not. We suggest R. petersi mayless depend on forest habitat than previously suspected, consistent with anecdotalreports of sengis nesting in intervening agricultural habitat. From a conservationviewpoint, this sengi species therefore appears robust to the current spatial andtemporal scale of habitat fragmentation.
Happily together forever: temporal variation in spatial patterns and complete lack of territoriality in a promiscuous rodent
(2013-08-31) Borremans, B.; Hughes, N. K.; Reijniers, J.; Sluydts, V.; Katakweba, A. A. S.; Mulungu, Loth S.; Sabuni, C. A; Makundi, Rhodes H.; Leirs, H.
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.
Happily together forever: temporal variation in spatial patterns and complete lack of territoriality in a promiscuous rodent
(The Society of Population Ecology and Springer Japan, 2014-01) Borremans, B.; Hughes, N. K.; Reijniers, J.; Sluydts, V.; Katakweba, A. A. S.; Mulungu, Loth S.; Sabuni, C. A.; Makundi, Rhodes H.; Leirs, H.
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.
Lepus conference soils, land use and plague Lushoto, Tanzania
(Sokoine University of Agriculture, 2013-08) Hieronimo, P.; Meliyo, J.; Gulinck, H.; Kimaro, D.; Msanya, B.; Mulungu, L.; Kihupi, N.; Deckers, S.; Leirs, H.; Leirs, H.
This excursion guide leads you to the case study area of the LEPUS project. The study area is located in a 200 km2 section of the Western Usambara Mountains and within the Lushoto district (map 1 ). I t is centred over the region in which during the period 1 980 - 2004 many bubonic plague cases were registered. Within the case area, there is west-east gradient from high to low plague incidence.
Lepus conference soils, land use and plague Lushoto, Tanzania
(2013) Hieronimo, P.; Meliyo, J.; Gulinck, H.; Kimaro, D.; Msanya, B. M.; Mulungu, L.; Kihupi, N.; Deckers, S.; Leirs, H.
Pcr detection of Leptospira DNA in rodents and insecti- vores from Tanzania
(Sokoine University of Agriculture, 2005-12) Mgode, G.F.; Mhamphi, G.; Katakweba, A.; Paemelaere, E.; Willekens, N.; Leirs, H.; Machang, R.S.; Hartskeerl, R.A.
The true prevalence of leptospirosis in Tanzania is unknown or underestimated. In this study we report on the prevalence of leptospirosis in Morogoro, Tanzania, by PCR detection of leptospiral DNA in 27 kid- neys of rodents (Mastomys spp, Rattus spp, and Mus spp) and insectivores (Crocidura spp). The PCR study comple- mented previous attempts to isolate the leptospires and to perform seroprevalence by the microscopic agglutination test (MAT). Results of this study indicated an overall detection rate of 11 % by PCR, 7.4% by isolation and 0% by the MAT. Based on our analysis, it is recommended to use PCR and isolation for the detection of leptospires in potential host animals.
Preliminary investigation on rodent–ectoparasite associations in the highlands of Tigray, Northern Ethiopia: implications for potential zoonoses
(Integrative Zoology, 2011) Yonas, M.; Welegerima, K.; Laudisoit, A.; Bauer, H.; Gebrehiwot, K.; Deckers, S.; Katakweba, A.; Makundi, R.; Leirs, H.
We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray, Northern Ethiopia. Ectoparasite infestation indices, such as percent infestation, mean abundance, prevalence and host preferences, were calculated for each taxon. In total, 172 rodents from crop fields and 97 from household compounds were trapped. Rodent species and numbers trapped from the crop fields and household compounds were Mastomys awashensis (Lavrenchenko, Likhnova & Baskevich, 1998) (88 and 44), Arvicanthis dembeensis (Ruppel, 1842) (63 and 37) and Acomys sp. (21 and 16), respectively. A total of 558 insects and acarids (belonging to 11 taxa) were recovered from the rodents trapped in the crop fields, and 296 insects and acarid (belonging to 6 taxa) from the rodents trapped in the household compounds. Approximately 66% of the rodents trapped from the crop fields and 47% of those trapped from the household compounds were infested with ectoparasites. Laelaps sp. (64.9%) and Xenopsylla sp. (20.6%) comprised the highest proportion of the ectoparasites recovered in the crop fields, and the same ectoparasites, but in reverse order, comprised the highest proportions in the household compounds (Xenopsylla [50.3%] and Laelaps sp. [29%]). Our study revealed that crop fields and household compounds in the highlands share similar rodents and several ectoparasites. Furthermore, at least 1 of the rodent species and some of the ectoparasites identified in this study were reported to have posed medical and veterinary threats in other parts of Ethiopia and neighboring countries.
Preliminary investigation on rodent–ectoparasite associations in the highlands of Tigray, Northern Ethiopia: implications for potential zoonoses
(Integrative Zoology, 2011) Yonas, M.; Welegerima, K.; Laudisoit, A.; Bauer, H.; Gebrehiwot, K.; Deckers, S.; Katakweba, A.; Makundi, R.; Leirs, H.
We studied associations between rodents and their arthropod ectoparasites in crop fields and household compounds in the highlands of Tigray, Northern Ethiopia. Ectoparasite infestation indices, such as percent infestation, mean abundance, prevalence and host preferences, were calculated for each taxon. In total, 172 rodents from crop fields and 97 from household compounds were trapped. Rodent species and numbers trapped from the crop fields and household compounds were Mastomys awashensis (Lavrenchenko, Likhnova & Baskevich, 1998) (88 and 44), Arvicanthis dembeensis (Ruppel, 1842) (63 and 37) and Acomys sp. (21 and 16), respectively. A total of 558 insects and acarids (belonging to 11 taxa) were recovered from the rodents trapped in the crop fields, and 296 insects and acarid (belonging to 6 taxa) from the rodents trapped in the household compounds. Approximately 66% of the rodents trapped from the crop fields and 47% of those trapped from the household compounds were infested with ectoparasites. Laelaps sp. (64.9%) and Xenopsylla sp. (20.6%) comprised the highest proportion of the ectoparasites recovered in the crop fields, and the same ectoparasites, but in reverse order, comprised the highest proportions in the household compounds (Xenopsylla [50.3%] and Laelaps sp. [29%]). Our study revealed that crop fields and household compounds in the highlands share similar rodents and several ectoparasites. Furthermore, at least 1 of the rodent species and some of the ectoparasites identified in this study were reported to have posed medical and veterinary threats in other parts of Ethiopia and neighboring countries.
The prevalence of Mycobacterium bovis-infection and atypical mycobacterioses in cattle in and around Morogoro, Tanzania
(Springer Science + Business Media B.V., 2009) Durnez, L.; Sadiki, H.; Katakweba, A.; Machang’u, R. R.; Kazwala, R. R.; Leirs, H.; Portaels, F.
A study was conducted to determine the prevalence of Mycobacterium bovis-infection and atypical mycobacterioses in different cattle herd management systems in and around Morogoro, Tanzania. Between April and June 2005, a total of 728 bovines from 49 herds were tested for M. bovisinfection and atypical mycobacterioses. Milk samples were taken from tuberculin positive animals and analysed for the presence of mycobacteria. Total prevalences of 2.5% and 10.1% were found for M. bovisinfection and atypical mycobacterioses respectively, with more M. bovis-infection in cattle in the extensive management system and more atypical mycobacterioses in cattle in the intensive management system. From 8 out of 42 milk samples (19%) atypical mycobacteria were cultured. A higher prevalence of M. bovisinfection in the extensive sector could be due to several factors. In addition, such high prevalence puts herd owners and their families at risk for BTB. Therefore control of BTB, as well as education of cattle owners is important, especially in the extensive sector.
Seasonal and habitat dependence of fleas parasitic on small mammals in Tanzania
(ISZS, Blackwell Publishing and IOZ/CA, 2009) Laudisoit, A.; Leirs, H.; Makundi, R.; Krasnov, B. R.
We investigated host and flea species composition across different habitats during dry and rainy seasons in the Western Usambara Mountains in Tanzania. During both seasons, similarity in flea species composition increased with an increase in the similarity in host species composition. Nevertheless, between-season within-habitat as well as within-season between-habitat similarity in host species composition was higher than similarity in flea species composition. Ordination of habitats according to their host and flea species composition demonstrated that the pattern of between-habitat similarity in both host and flea species composition varied seasonally. Despite the relatively rich mammal and flea fauna of the study region, the major contribution to variation in species composition between seasons and among habitats was due to a few species only. Flea assemblages on Lophuromys kilonzoi Verheyen et al., 2007 and Praomys delectorum Thomas, 1910 in different habitats were equally similar in either season. In contrast, flea assemblages on Mastomys natalensis (Smith, 1834) occurring in different habitats were more similar in the dry than in the rainy season, whereas the opposite was the case for fleas on Grammomys sp. In different hosts, the main differences in species composition of flea assemblages between seasons as well as among habitats were due to different flea species. Although our results support the earlier idea that parasite species composition is determined by both host species composition and habitat properties, the former appears to explain variance in flea species composition between localities in the tropics better than between localities in temperate and arid zones.
A systematic review of rodent pest research in Afro-Malagasy small-holder farming systems: are we asking the right questions?
(PLOS ONE, 2017) Swanepoel, L. H.; Swanepoel, C. M.; Brown, P. R.; Eiseb, S. J.; Goodman, S. M.; Keith, M.; Kirsten, F.; Leirs, H.; Mahlab, T. A. M.; Makundi, R. H.; Malebane, P.; Maltitz, E. F.; Massawe, A. W.; Monadjem, A.; Mulungu, L. S.; Singleton, G. R.; Taylor, P. J.; Soarimalala, V.; Belmain, S. R.
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
When viruses don’t go viral: the importance of host phylogeographic structure in the spatial spread of arenaviruses
(Public Library of Science, 2017) Gryseels, S.; Baird, S. J. E.; Borremans, B.; Makundi, R.; Leirs, H.; Bellocq, J. G.
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. natalensisborne arenavirus, Lassa virus, are limited to West Africa
Winning the fight against rodent pests: Recent developments in Tanzania
(Asian Network for Scientific Information, 2010) Mulungu, L. S.; Ngowo, D. V.; Makundi, R. H.; Massawe, A. W.; Leirs, H.
Rodent management programs in Tanzania have been reactive and did not consider the population ecology of the target species. The strategies used to manage rodents were probably most suited to managing low-density rodent populations and were selected to solve localised rodent problems in certain areas. These included bounty schemes, burning of homes and vegetation, trapping and poisoning. In recent years, new developments in rodent pest management include a system designed to provide early warning of potent damage. An understanding of the population processes that give rise to rodent pest's problems provides the framework for evaluating the causes and solutions. Population models for predicting outbreaks have been developed. These have incorporated simulations and aspects of economics in the implementation of control strategies. Simulation based on Bioeconomics models have shown that the most economically rewarding strategies differ significantly from current practices of symptomatic treatment when severe rodent damage is noticed in the fields. Therefore, shifting from symptomatic practices and controlling rodents on a calendar basis can substantially improve the economic conditions for the majority of maize products in Tanzania.