Gastrointestinal parasite infection of the Gray mouse lemur (Microcebus murinus) in the littoral forest of Mandena, Madagascar: Effects of forest fragmentation and degradation

Faecal material from 169 individuals of Microcebus murinus living in five littoral forest fragments was analyzed for gastrointestinal parasites. The fragments differed in size and forest quality. Gastrointestinal parasite infection of M. murinus was characterised using parasite species richness, the prevalence of parasites, and the intensity of infection expressed as the number of parasite eggs, larvae and cysts per gram of faeces. For this, a modification of the McMaster flotation egg counting technique was applied to analyze egg shedding. We recorded nine gastrointestinal parasite species in faecal samples of Microcebus murinus. In good quality forest lemurs from a smaller fragment had higher prevalences and intensities of infection of gastrointestinal nematodes and protozoans than animals from a larger forest fragment. In large forests, excretion of eggs from Ascarididae and tapeworms was higher in a degraded forest fragment than in a good quality forest fragment. This situation was reversed in small forest fragments with fewer eggs of Suburula nematodes and protozoans shed by lemurs in the degraded fragment than by lemurs from the good quality fragment. Our analyses are hampered by the fact that we had only one forest fragment per type of treatment. Keeping this limitation in mind, the results are consistent with other studies and indicate that forest degradation and fragmentation have marked effects on the level of parasitism of Madagascar’s lemurs.RÉSUMÉDes matières fécales de 169 individus de Microcebus murinus vivant dans cinq fragments de forêt littorale du sud de Madagascar ont été analysées par la méthode modifiée de flottaison de McMaster. Ces animaux avaient été capturés entre avril 2003 et octobre 2005. Les fragments de forêt diffèrent entre eux par la taille et le degré de dégradation. Pour étudier l’impact de la fragmentation et de la dégradation de la forêt sur l’infestation parasitaire de cette espèce de lémurien, trois critères ont été évalués qui sont le nombre d’espèces de parasite, la prévalence et l’intensité de l’infestation. Les fragments ayant des tailles différentes mais montrant un même type de dégradation ont fait l’objet d’une comparaison au même titre que des fragments présentant un même degré de dégradation mais de mêmes tailles. Neuf espèces de parasites gastro-intestinaux ont été recensées chez Microcebus murinus de la forêt de Mandena dont six nématodes avec une espèce non-identifiée de la famille des Ascarididae et de l’ordre des Strongylida, Trichuris sp., deux espèces d’Oxyuridae dont l’une est du genre Lemuricola et une autre qui n’est pas encore identifiée, Subulura sp., deux cestodes appartenant au genre Hymenolepis et un protozoaire de l’ordre des Coccidia. La fragmentation et la dégradation de la forêt de Mandena affectent le parasitisme de cette espèce de lémurien. Les deux tendances qui ressortent de cette étude sont, d’une part, une augmentation de l’intensité et de la prévalence des parasites gastro-intestinaux de Microcebus murinus dans les plus petits fragments forestiers et d’autre part, une augmentation qui semble être en relation avec le degré de dégradation de la forêt dans les plus grands fragments. L’augmentation du nombre d’espèces de parasites avec la taille des fragments peut être une conséquence de la taille des fragments ou du nombre d’animaux échantillonnés. Dans les grands fragments, les microcèbes sont plus souvent infestés par les deux espèces de cestode lorsqu’ils sont dans des forêts dégradées que dans les fragments plus ou moins intacts. Dans les plus grandes parcelles forestières, la prévalence et l’intensité de l’infestation parasitaire sont plus élevées chez les microcèbes vivant dans les fragments très dégradés. Ce fait pourrait être dû à la réduction ou la perte de l’habitat associée à l’organisation sociale de l’animal car M. murinus dort en groupe pendant le jour, de sorte qu’une réduction de son habitat pourrait favoriser une augmentation des contacts interindividuels et la transmission de parasites, bien que l’infestation des microcèbes n’était pas liée à la densité des hôtes d’une manière significative. En connaissant l’effet néfaste des parasites, cette étude contribuerait à l’amélioration de la conservation de la biodiversité en relation avec les risques et les bénéfices des activités d’exploitation et de gestion de l’écosystème

Primates in peril: the significance of Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo for global primate conservation

Primates occur in 90 countries, but four—Brazil, Madagascar, Indonesia, and the Democratic Republic of the Congo (DRC)—harbor 65% of the world’s primate species (439) and 60% of these primates are Threatened, Endangered, or Critically Endangered (IUCN Red List of Threatened Species 2017-3). Considering their importance for global primate conservation, we examine the anthropogenic pressures each country is facing that place their primate populations at risk. Habitat loss and fragmentation are main threats to primates in Brazil, Madagascar, and Indonesia. However, in DRC hunting for the commercial bushmeat trade is the primary threat. Encroachment on primate habitats driven by local and global market demands for food and non-food commodities hunting, illegal trade, the proliferation of invasive species, and human and domestic-animal borne infectious diseases cause habitat loss, population declines, and extirpation. Modeling agricultural expansion in the 21st century for the four countries under a worst-case-scenario, showed a primate range contraction of 78% for Brazil, 72% for Indonesia, 62% for Madagascar, and 32% for DRC. These pressures unfold in the context of expanding human populations with low levels of development. Weak governance across these four countries may limit effective primate conservation planning. We examine landscape and local approaches to effective primate conservation policies and assess the distribution of protected areas and primates in each country. Primates in Brazil and Madagascar have 38% of their range inside protected areas, 17% in Indonesia and 14% in DRC, suggesting that the great majority of primate populations remain vulnerable. We list the key challenges faced by the four countries to avert primate extinctions now and in the future. In the short term, effective law enforcement to stop illegal hunting and illegal forest destruction is absolutely key. Long-term success can only be achieved by focusing local and global public awareness, and actively engaging with international organizations, multinational businesses and consumer nations to reduce unsustainable demands on the environment. Finally, the four primate range countries need to ensure that integrated, sustainable land-use planning for economic development includes the maintenance of biodiversity and intact, functional natural ecosystems

L'infestation parasitaire de Microcebus murinus de la forêt littorale de Mandena, Madagascar

So far parasitological studies were concentrated on large primates such as apes and monkeys. This is probably due to epidemiological interest because apes, which are genetically closer to humans, are known to be a reservoir of certain pests and diseases fatal to humans and vice versa. Prosimian gastrointestinal parasites are less studied. The goal of this project was to assess and describe the gastro-intestinal parasites of the lemur species Microcebus murinus from the littoral forest fragments of Mandena, southeastern Madagascar. In addition I wanted to evaluate the utility of determining gastro-intestinal parasite loads based on fecal samples. From April 2003 to October 2005, a total of 427 fecal samples from 169 different individuals of M. murinus from five forest fragments were analyzed to assess the parasite species richness of this lemur species based on parasite larvae and egg morphology. Three individuals of M. murinus were also sacrified in order to look for adult worms for identification and confirmation of parasite species, and to localize their gastro-intestinal parasites in the digestive tract. Screening all fecal samples by using the modified technique of the McMaster flotation, I noted that Microcebus murinus harbored nine different forms of intestinal parasites, and six of them were nematodes: a member of the Ascarididae family, one species of the Subuluridae family represented by the genus Subulura, an unidentified Strongylida, a species of the genus Trichuris (Trichuridae), two forms of the Oxyuridae family, one from the genus Lemuricola and the other still unidentified. For the Plathelminthes, two cestodes of the genus Hymenolepis (Hymenolepididae) were found and one species of Protozoa, belonging to the Coccidia order. These gastrointestinal parasites of M. murinus from Mandena have not been described as parasites of M. murinus yet. The cestode infection of this lemur deserves special attention because no study has reported lemurs infected by cestodes up to now. Adult worms of the Trichuris species were found in the caecum. I localized Lemuricola worms in the caecum and large intestine. Subulura worms were more abundant in the caecum than in the small and large intestine. A large number of Subulura larvae has been observed in the caecum. As exemplified by the data on Subulura sp. worms in the digestive tract of M. murinus, the number of nematode parasite eggs and larvae found in the feces are correlated with the intensity of infection in the digestive tract.RÉSUMÉCe travail avait pour but de décrire les parasites gastro-intestinaux du lémurien Microcebus murinus de la forêt littorale fragmentée de Mandena et d’évaluer l’analyse des parasites basée sur des échantillons de fèces. Des matières fécales au nombre de 427 provenant de 169 individus de M. murinus vivant dans cinq fragments de forêt ont été analysées. Trois individus de M. murinus ont été sacrifiés et autopsiés en vue d’une identification des vers parasite qui ont pondu chaque type d’oeuf trouvé dans les excréments et afin de voir leurs localisations dans le tube digestif de l’animal. Microcebus murinus héberge neuf espèces de parasites gastro-intestinaux dont six nématodes avec une espèce non-identifiée d’Ascarididae, une espèce de Subuluridae du genre Subulura, une espèce de l’ordre des Strongylida et du genre Trichuris (Trichuridae), deux espèces d’Oxyuridae dont l’une est du genre Lemuricola et l’autre reste encore non-identifiée, deux cestodes appartenant au genre Hymenolepis (Hymenolepididae) et un protozoaire de l’ordre des Coccidia. Comparés à toutes les études déjà faites auparavant sur les parasites gastro-intestinaux de M. murinus, les parasites hébergés par les microcèbes de Mandena appartiennent à d’autres espèces que celles qui étaient déjà connues pour infester cette espèce de lémurien. De cette étude, je suggère que le nombre d’oeufs et de larves de Subulura sp. trouvés dans les matières fécales pourrait refléter l’intensité de l’infestation des microcèbes par cette espèce de parasite

Host sex and age influence endoparasite burdens in the gray mouse lemur

International audienceIntroduction: Immunosenescence (deteriorating immune function at old age) affects humans and laboratory animals, but little is known about immunosenescence in natural populations despite its potential importance for population and disease dynamics and individual fitness. Although life histories and immune system profiles often differ between the sexes, sex-specific effects of aging on health are rarely studied in the wild. Life history theory predicts that due to their shorter lifespan and higher investment into reproduction at the expense of immune defences, males might experience accelerated immunosenescence. We tested this hypothesis by examining sex-specific age trajectories of endoparasite burden (helminth prevalence and morphotype richness measured via fecal egg counts), an indicator of overall health, in wild gray mouse lemurs (Microcebus murinus). To account for potential interactions between seasonality and host sex or age we examined the predictors of parasite burdens separately for the dry and rainy season. Results: Contrary to the prediction of immunosenescence, parasite prevalence and morphotype richness decreased at old age in the dry season, indicating acquired immunity by older animals. This pattern was primarily caused by within-individual decline in parasite loads rather than the earlier mortality of highly parasitized individuals. With the exception of an increasing cestode prevalence in males from yearlings to prime age in the rainy season, no evidence was found of male-biased ageing in parasite resistance. Besides this sex*age interaction, host age was uncorrelated with rainy season parasite loads. Seasonality did not affect the overall parasite loads but seasonal patterns were found in the predictors of parasite prevalence and morphotype richness. Conclusions: These results provide rare information about the age-related patterns of health in a wild vertebrate population and suggest improvement rather than senescence in the ability to resist helminth infections at old age. Overall, males appear not to suffer from earlier immunosenescence relative to females. This may partially reflect the earlier mortality of males, which can render senescence difficult to detect. While helminth infections are not strongly associated with survival in wild gray mouse lemurs, parasite load may, however, reflect overall good phenotypic quality of long-lived individuals, and is a potential correlate of fitness

Additional file 1: of Host sex and age influence endoparasite burdens in the gray mouse lemur

Additional results for Hämäläinen et al. "Host sex and age influence endoparasite burdens in the gray mouse lemur". (PDF 875 kb