Habitat fragmentation and vegetation structure impact gastrointestinal parasites of small mammalian hosts in Madagascar

Abstract

Deleterious effects of habitat loss and fragmentation on biodiversity have been demonstrated in numerous taxa. Although parasites represent a large part of worldwide biodiversity, they are mostly neglected in this context. We investigated the effects of various anthropogenic environmental changes on gastrointestinal parasite infections in four small mammal hosts inhabiting two landscapes of fragmented dry forest in northwestern Madagascar. Coproscopical examinations were performed on 1,418 fecal samples from 903 individuals of two mouse lemur species, Microcebus murinus ( n = 199) and M. ravelobensis ( n = 421), and two rodent species, the native Eliurus myoxinus ( n = 102) and the invasive Rattus rattus ( n = 181). Overall, sixteen parasite morphotypes were detected and significant prevalence differences between host species regarding the most common five parasites may be explained by parasite–host specificity or host behavior, diet, and socioecology. Ten host‐ and habitat‐related ecological variables were evaluated by generalized linear mixed modeling for significant impacts on the prevalence of the most abundant gastrointestinal parasites and on gastrointestinal parasite species richness (GPSR). Forest maturation affected homoxenous parasites (direct life cycle) by increasing Lemuricola , but decreasing Enterobiinae gen. sp. prevalence, while habitat fragmentation and vegetation clearance negatively affected the prevalence of parasites with heterogenic environment (i.e., Strongyloides spp.) or heteroxenous (indirect cycle with intermediate host) cycles, and consequently reduced GPSR. Forest edges and forest degradation likely change abiotic conditions which may reduce habitat suitability for soil‐transmitted helminths or required intermediate hosts. The fragility of complex parasite life cycles suggests understudied and potentially severe effects of decreasing habitat quality by fragmentation and degradation on hidden ecological networks that involve parasites. Since parasites can provide indispensable ecological services and ensure stability of ecosystems by modulating animal population dynamics and nutrient pathways, our study underlines the importance of habitat quality and integrity as key aspects of conservation.

Helminth-host-environment interactions: Looking down from the tip of the iceberg

“…Helminths have also been affected by land-use change (White & Razgour 2020). The impact of deforestation and associated habitat fragmentation on nematodes in two small primates and two rodents from Madagascar was recently shown to depend on the type of nematode life cycle (Kiene et al 2021). Although habitat fragmentation had no detectable impact on direct life cycle pinworms whose eggs remain around the rodent anus, pinworms were more common in mature forests that would provide tree holes for the gray mouse lemur Microcebus murinus.…”

Seasonal changes in the parasite prevalence of a small Malagasy lemur species (Lepilemur edwardsi)

“…Microcebus murinus, another lemur species that rests in tree hollows, also showed a higher Lemuricola sp. prevalence than the closely related Microcebus ravelobensis, which rests in leaf nests during the day (Kiene et al 2021). The sportive lemurs' tree hollows are an ideal habitat for intestinal parasites and also ectoparasites, as they are often dark and humid and frequently visited by their inhabitants (Rasoloharijaona et al 2003;Hokan et al 2018).…”

Gastrointestinal parasites in wild rodents in Chiloé Island-Chile

“…Likewise, individuals with high body mass can harbor more parasites since a larger habitat favor parasite colonization, while individuals with low body condition can exhibit reduced immune competence related to nutrients deficiency and an increase in parasitosis (Wilson et al, 2002;Morand, 2015). In addition, environmental characteristics that influence parasitic infections include altitude, climate (e.g., temperature, humidity), habitat quality, among others (Wells et al, 2007;Barelli et al, 2021;Deak et al, 2020;Kiene et al, 2021). Effects of helminths and protozoa infections on rodents living in human-modified habitats can be intensified with detrimental impact at host population scale (Santicchia et al, 2015).…”