Weibchenassoziationen und Fortpflanzungsstrategien beim Grauen Mausmaki (Microcebus murinus) in Nordwest-Madagaskar

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Determinants of helminth infection in a subterranean rodent, the Cape dune mole-rat (Bathyergus suillus)

The helminth fauna of the largest bathyergid, the Cape molerat (Bathyergus suillus) was studied throughout an entire calendar year. The species richness encountered was low, with only 3 species of nematodes (Longistriata bathyergi, Mammalakis macrospiculum, and Trichostrongylus sp.) and 2 species of cestodes (Taenia sp. and Rodentolepis sp.). At less than 10%, the prevalence for all helminths species was similarly low and may be a result of the solitary lifestyle and the subterranean habitat exploited by this rodent. Clear seasonal patterns were apparent for the most common nematode (L. bathyergi), and prevalence and abundance were highest among non-pregnant females compared to males and pregnant females. Dispersal patterns associated with the mating system of the host could explain this pattern. In contrast, the prevalence of the most common cestode (Taenia sp.) was neither determined by season nor host sex, suggesting that foraging habits may constantly expose B. suillus to this parasite.http://asp.unl.edu/index.php?option=com_content&view=article&id=39&Itemid=48ab201

Possible modulatory effects of male cues and social system on luteinizing hormone and pituitary sensitivity in two African mole-rats

The current study set out to investigate the potential effects of olfactory stimuli on the basal circulating levels of luteinizing hormone (LH) and the response of the pituitary to an exogenous gonadotropin-releasing hormone (GnRH) challenge in two mole-rat species with induced ovulation but contrasting mating and social systems. Females were either kept in isolation, allowed only olfactory and auditory contact or in physical contact with a male. Basal LH as well as pituitary challenged LH blood samples were collected after six hours. Post-challenge LH levels were significantly elevated compared to baseline levels in both species. However, neither basal nor post-challenge LH levels differed significantly between treatments for females of either species. At the same time, while baseline LH was comparable between the two species, post-challenge levels were significantly greater for the solitary species. Our findings negate a modulatory role of male cues on LH levels but suggest increases in pituitary sensitivity in the solitary species. This could enhance reproductive success in species with only sporadic encounters between the sexes and merits further studies in other species.The National Research Foundation. N.C.B. acknowledges funding for a DST-NRF SARChI Chair of Mammalian Behavioural Ecology and Physiology. H.L. acknowledges a postdoctoral research fellowship from the University of Pretoria.http://www.bioone.org/loi/afzoab201

Endoparasites of the eastern rock sengi (Elephantulus myurus) from South Africa

The endoparasite fauna of the eastern rock sengi (Elephantulus myurus Thomas and Schwann) was studied for the first time for any sengi species from September 2007 until August 2008 in the Limpopo Province of South Africa. From the 121 sengis examined, we recovered 11 endoparasite taxa including 9 nematodes, 1 cestode family (Hymenolepididae) and 1 pentastomid species [Armillifer armillatus (Wyman, 1834)]. The overall endoparasites prevalence was high at 100% and largely attributable to the nematode Maupasina weissi Seurat, 1913, with only a single individual being parasite free. Despite the high diversity, species richness was low (1.58 ± 0.06) and only M. weissi and spiruroid larvae occurred at a prevalence exceeding 8%. The abundance of M. weissi varied significantly between seasons and was lowest in summer and autumn. In contrast, the abundance of spiruroid larvae remained relatively constant across seasons in males but was significantly higher in spring and summer compared to winter in females. These patterns may be generated by an accumulation of M. weissi with age as well as sex-specific seasonal shifts in diet. An updated list on the hosts and geographic range of parasites of sengis is provided.NRF and the University of Pretoria.http://digitalcommons.unl.edu/jrnlparasitologyhb201

Endoparasites of the spiny mouse (Acomys spinosissimus) from South Africa

The endoparasite fauna of the spiny mouse (Acomys spinosissimus) was studied for the first time from April 2007 until April 2009 in a population from the Limpopo Province of South Africa. In a total of 129 mice examined, only 6 endoparasite taxa were found, 2 nematode species (Syphacia minuta, Monanema joopi), 1 genus of cestodes (Rodentolepis spp.), and unidentified hymenolepidid fragments. In addition, 1 pentastomid species (Armillifer grandis) as well as unidentified porocephalid specimens were recovered. The overall prevalence was low, at 15.5%, and only 1 individual harbored more than 1 parasite species. With 12.4% prevalence, S. minuta was the most prevalent parasite. Its prevalence and abundance were significantly higher during the dry and cooler season than during the wet and warm season, while a female-biased burden was observed during the wet season only. For the remaining parasite species, low prevalence prevented meaningful statistical analyses. The observed parasite species richness, prevalence, and abundance for A. spinosissimus were low compared to values reported for other Acomys spp. This may be linked to the lack of anthropogenic influences in the study population as well as the small size of A. spinosissimus.http://www.journalofparasitology.org/loi/parahb201

Energetic Benefits of Sociality Offset the Costs of Parasitism in a Cooperative Mammal

We thank the owners for access to their property for animal capture and KwaZulu-Natal Nature Conservation Service for issuing the capture permit. This research was funded by the NRF-SAR Chair for Mammalian Behavioural Ecology and Physiology to NCB and University of Pretoria PDRF's to MS and HL. Many assistants were involved with fieldwork but we would especially like to thank Marietjie Oosthuizen and Craig Jackson for their help. This research was funded by the Department of Science and Technology/National Research Foundation-South African Research Chairs Initiative Chair for Mammalian Behavioural Ecology and Physiology to N.C.B. and University of Pretoria Postdoctoral Research Fellowships to M.S. and H.L. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD

Abiotic and biotic determinants of tick burdens in the eastern rock sengi (Elephantulus myurus)

Ticks are important vectors of pathogens of medical and veterinary importance worldwide. Despite their economic importance our current knowledge about the factors affecting tick prevalence and abundance in tropical and subtropical regions is rather limited. Both abiotic (e.g. temperature) as well as biotic variables (e.g. host sex) have been identified as key determinants of distributions. Eastern rock sengis or elephant shrews (Elephantulus myurus, Thomas & Schwann) are widely distributed throughout Africa and can harbour a large number of tick species and substantial tick burdens. In the current study we evaluated the contribution of climate and host factors on tick burdens of sengis. Throughout the year sengis carried high abundances of immature stages of a single tick species, Rhipicephalus sp. near warburtoni. There was no evidence that host parameters affected tick burdens. However, larval abundance decreased with increasing ambient temperatures and both larvae and nymphs were negatively affected by rainfall two months prior to the sampling month. In addition, nymphal burdens decreased with increasing minimum temperatures. Our results suggest that climate factors are the largest constraint for the immature stages of R. sp. near warburtoni and that eastern rock sengis could play a crucial role in the dynamics of tick-borne diseases due to the large tick burdens they can sustain.KM was supported by a doctoral grant from the NRF and HL by a Research Fellowship from the University of Pretoria. IGH acknowledges funding from the University of Pretoria and the NRF.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-2915ab201

Effects of life-history traits on parasitism in a monogamous mammal, the eastern rock sengi (Elephantulus myurus)

The distribution of parasites is often characterised by substantial aggregation with a small proportion of hosts harbouring the majority of parasites. This pattern can be generated by abiotic and biotic factors that affect hosts and determine host exposure and susceptibility to parasites. Climate factors can change a host’s investment in life-history traits (e.g. growth, reproduction) generating temporal patterns of parasite aggregation. Similarly, host age may affect such investment. Furthermore, sex-biased parasitism is common among vertebrates and has been linked to sexual dimorphism in morphology, behaviour and physiology. Studies exploring sex-biased parasitism have been almost exclusively conducted on polygynous species where dimorphic traits are often correlated. We investigated the effects of season and life-history traits on tick loads of the monogamous eastern rock sengi (Elephantulus myurus). We found larger tick burdens during the non-breeding season possibly as a result of energetic constraints and/or climate effects on the tick. Reproductive investment resulted in increased larval abundance for females but not males and may be linked to sex-specific life-history strategies. The costs of reproduction could also explain the observed age effect with yearling individuals harbouring lower larval burdens than adults. Although adult males had the greatest larval tick loads, host sex appears to play a minor role in generating the observed parasite heterogeneities. Our study suggests that reproductive investment plays a major role for parasite patterns in the study species.National Research Foundation (NRF), HL a Research Fellowship from the University of Pretoria and IGH funding from the University of Pretoria.http://www.springerlink.com/content/0028-1042/nf201

Natural parasite infection affects the tolerance but not the response to a simulated secondary parasite infection

Parasites deplete the resources of their host and can consequently affect the investment in competing traits (e.g. reproduction and immune defence). The immunocompetence handicap hypothesis posits that testosterone (T) mediates trade-offs between parasite defence and reproductive investment by suppressing immune function in male vertebrates while more recently a role for glucocorticoids (e.g. cortisol (C)) in resource allocation has been suggested. These hypotheses however, have not always found support in wild animals, possibly because most studies focus on a single parasite species, whereas infections with multiple parasites are the rule in nature. We measured body mass, T- and C-levels of wild male highveld mole-rats (Cryptomys hottentotus pretoriae) naturally uninfected or infected with a cestode (Mathevotaenia sp.) right after capture. Subsequently, we injected animals subcutaneously with a lipopolysaccharide (LPS) to simulate a bacterial infection and recorded changes in body mass, food intake, haematological parameters and hormone levels. As a control, animals were injected with saline. Natural infection neither affected initial body mass nor C-levels, whereas infected males had significantly reduced T-levels. We observed significant reductions in food intake, body mass and T in response to LPS but not saline while C increased. However, this response did not vary with infection status. In contrast, final body mass and some haematological parameters were significantly lowered in infected males. Our results suggest that naturally infected males are able to compensate for resource depletion by physiological adjustments. However, this leaves them less tolerant to the challenges of a secondary infection.The Department of Science and Technology/National Research Foundation South African Research Chair for Behavioural Ecology and Physiology to NCB and HL acknowledges funding through a Research Fellowship by the University of Pretoria.http://www.plosone.orgam201

Monanema joopi n. sp. (Nematoda, Onchocercidae), parasite d’Acomys (Acomys) spinosissimus Peters, 1852 (Muridae) en Afrique du Sud, et commentaires sur ce genre de filaire

Monanema joopi n. sp. is described from blood drawn from the heart of the murid Acomys (Acomys) spinosissimus in South Africa. It is characterised by a non-bulbous cephalic extremity, shared with only one of its five congeners, and a cylindrical tail with caudal alae and a spicular ratio of 2.7 in the male. As is typical for the genus, microfilariae are skin-dwelling. They are 185 to 215 micrometres long and have no refractory granules beneath their sheath. A key to the species of Monanema is presented and an amended generic description, based on the six currently known species, is proposed. Species of Monanema are primarily lymphatic and the low intensity of infection with M. joopi n. sp. in blood from the heart, might suggest that not all adults settle in the heart cavities. One might also consider that other, more susceptible rodents serve as hosts for this parasite as well. To date, the geographic range of Monanema includes North America, Africa and Australia, each with representatives of a different lineage. Given the present hypotheses on the evolutionary origin and subsequent migrations of rodents, we expect the origin of Monanema to be in the Palearctic-Oriental region.Description de Monanema joopi n. sp., récolté dans le sang cardiaque d’Acomys (Acomys) spinosissimus en Afrique du Sud. L’espèce est caractérisée par une extrémité céphalique non bulbeuse, partagée avec un seul des cinq congénères, et chez le mâle, une queue cylindrique avec des ailes caudales et un rapport spiculaire de 2,7. Les microfilaires sont dermiques, ce qui est caractéristique du genre. Elles sont longues de 185-215 μm et n’ont pas de granules réfringents sous la gaine. Une clé des espèces de Monanema est présentée, ainsi qu’un amendement de la définition générique, basée sur les six espèces. Les espèces de Monanema sont fondamentalement lymphatiques et la faible infection par M. joopi n. sp. dans le sang cardiaque permet de suspecter d’autres localisations des adultes. Il se peut aussi que d‘autres rongeurs plus réceptifs soient parasités. Actuellement, la distribution géographique de Monanema comprend l’Amérique du Nord, l’Afrique et l’Australie, et chaque région a des représentants de différentes lignées. D’après les hypothèses actuelles sur l’origine et les migrations ultérieures des rongeurs, nous pensons que Monanema est originaire de la région palearctico-orientale.Junker was sponsored during a two-month’s visit as invited professor by the Muséum National d’Histoire Naturelle, Paris, France. K. Medger was supported by a doctoral grant from the NRF and H. Lutermann by a Research Fellowship from the University of Pretoria.http://www.parasite-journal.org/am2013ab201