Macroparasitos em uma comunidade de anuros, Sertão, Rio Grande do Sul

Abstract

Amphibians are hosts to a wide variety of parasites. These parasitic organisms have different and complex transmission strategies and life histories. Assuming the hypothesis that agricultural areas negatively influence the richness and abundance of helminths, this study aimed to describe the helminths of the anuran community in the Municipal Natural Park of Sertão. Specifically, we (i) quantified the parasites collected in anurans captured in agricultural areas and in forestry; (ii) we evaluated the general richness of the parasite community in anurans; and (iii) we assessed the prevalence of parasites in frogs. The collection of anurans was carried out from October 2022 to March 2023 in two environments (forest and farmland). The anurans were collected using visual and auditory search techniques. After collection, the anurans were euthanized with 5% Lidocaine, and then necropsies were performed. To collect the parasites, we examined all organs of the gastrointestinal tract, lungs, heart, kidneys, bladder and abdominal cavity of the anurans. The parasites were fixed in 70% ethyl alcohol. Parasite richness was analyzed using sampling sufficiency curves using the EstimateS 9.1 program using richness estimators, Chao 1, 1st order Jack and Bootstrap. We tested possible differences in richness and prevalence between forest and crops using the Student's t test. We collected 54 hosts belonging to 15 species and five families (Brachycephalidae; Bufonidae; Hylidae; Leptodactylidae; Odontoprhynidae). We identified a total of 20 species of parasites (n= 281), belonging to the phyla Acanthocephala, Nematoda and Platyhelminthes. The most representative phylum was Nematoda, with 12 species, distributed in three families: Cosmocercidae (83.34%), Molineoidae (8.33%) and Physalopteriidae (8.33%). Individuals from the phylum Platyhelminthes belong to the class Trematoda and the family Plagiorchiidae. Acantocephalas belong to the Centrorhynchidae family. In the forest environment, we recorded seven species of anurans (n=20), with 18 specimens being parasitized with at least one species of parasite. We recorded 11 species of parasites in anurans in the forest environment (N=39), composed of 72.72% nematodes and 27.27% plathelminthes. Nematoda was represented in the forest by two families: Cosmocercidae (87.5%) and Molineoidae (12.5%) and the phylum Plathelminthes was represented by the family Plagiorchiidae (100%). In contrast, in the field we recorded 12 species of anurans (n=34), in which 44.11% of the specimens were parasitized with at least one species of parasite. We recorded 12 species of parasites (n= 26) belonging to the phyla Nematoda (58.33%), Platyhelminthes (33.33%), and Acanthocephala (8.33%). The Nematoda phylum was the most predominant in the crop with 7 species belonging to the families: Cosmocercidae (71.42%), Physalopteriidae (14.28%), and Molineoidae (14.28%). Platyhelminthes were represented by the families: Nematotaeniidae (25%); Proteocephalidae (75%) and the phylum Acanthocephala in the family Centrorhynchidae. We did not observe a significant difference in the richness, abundance, AM and IMI of parasites between the forest and the crops. The findings of this work provide a basis for future research on the ecology of parasites in anurans, especially in contexts of environmental changes induced by human activity.