Effects of habitat fragmentation on ectoparasite communities in mouse lemurs (Microcebus spp.) and small mammals in northwestern Madagascar
Habitat loss and fragmentation are reasons for a worldwide depletion of biodiversity. Malagasy ecosystems as biodiversity hotspots are particularly vulnerable. Although they may have profound effects on host and ecosystem integrity, fragmentation effects in parasites are largely understudied. This study aims to investigate if and how habitat fragmentation affects the composition of ectoparasite communities on small mammalian hosts in networks of tropical dry forest in Madagascar. Forest fragments differing in host density, size, shape, connectivity, and sites in the neighbouring continuous forest were studied in the Ankarafantsika National Park and the Mahamavo region in northwestern Madagascar. 923 individuals of two mouse lemur species, Microcebus murinus (n = 199) and M. ravelobensis (n = 426), and two rodent species, Eliurus myoxinus (n = 114) and Rattus rattus (n = 184), were captured for ectoparasite sampling. Ectoparasite prevalence and species richness were statistically related to 14 ecological variables by generalized linear modelling. The investigated host species harboured ticks (Haemaphysalis sp.), mites (Laelaptidae, Trombiculidae, Listrophoroides spp.), and sucking lice (Lemurpediculus spp., Polyplax spinulosa, Hoplopleura sp.). In mouse lemurs, ectoparasite prevalence and species richness were higher in continuous forest areas compared to fragments. Proximity to the forest edge led to a lower prevalence and host population density had a positive effect on the prevalence of temporary ectoparasites (ticks, Trombiculidae, Laelaptidae) of all investigated hosts. The results strongly suggest that habitat fragmentation and especially edge effects impact ectoparasite communities, in particular by affecting temporary parasite species. The results are best explained by an interplay of parasite-specific life cycles, different responses to abiotic factors, and a differential reaction of different host species to habitat fragmentation and edge effects. Due to a very basic knowledge on the role of parasites in biocenoses, consequences can hardly be assessed. Additional research is necessary for the conservation of stable ecosystems.