Helmintos associados a Aquarana catesbeiana (Shaw, 1802) (Anura: Ranidae) no extremo sul do Brasil: diversidade e relações parasito-hospedeiro

Abstract

Research into parasites associated with wild animals in Brazil is still scarce, especially in relation to helminths that parasitize anurans. The lack of knowledge about the diversity of helminths associated with Aquarana catesbeiana in Brazil, together with the species' predatory habit, highlight the importance of helminthological research. The aim of this study was to investigate the parasitic helminth fauna of A. catesbeiana frogs and tadpoles in the far south of Brazil. Between October 2019 and December 2021, 57 adult and juvenile frogs and 145 tadpoles of A. catesbeiana were collected in the municipalities of Pelotas (Cascata) and Capão do Leão (Zootecnia), Rio Grande do Sul. The helminths were collected and prepared for classification according to the usual techniques in helminthology. Prevalence rates (P%), mean infection intensity (MII), mean abundance (MA) and infection intensity (INi) were estimated for frogs and tadpoles. Helminth infections were analyzed in relation to sexual gender, body size and mass and between the two collection sites. The assembly of helminth parasites of A. catesbeiana frogs was composed of: Cosmocercidae gen. spp., Oxyascaris sp., Falcaustra sp., Spiroxys sp. (larvae), Acuariidae gen. sp. (larvae), Gyrinicola chabaudi, Spirocamallanus sp. (larvae) and Pharyngodonidae gen. spp. (Nematoda); Centrorhynchus sp. (cystacanth) and unidentified cystacanth (Acanthocephala) and Haematoloechus floedae (Digenea). The tadpoles were parasitized by Gyrinicola chabaudi, Spiroxys sp. (larvae), and Catadiscus sp. (Digenea). The prevalence of helminths was higher in males (regardless of location) and higher in the Cascata location (regardless of gender). The abundance of helminths showed a significant correlation with the body parameters of the anurans. The prevalence of Centrorhynchus sp. varied in relation to the maturity of the anurans, being higher in adults and with no differences between males and females. The study provides a checklist, which presents 97 vertebrate host taxa for 10 Centrorhynchus taxa recorded on the South American continent. The checklist showed that birds were the main definitive hosts, while snakes Dipsadidae and, anurans Hylidae and Leptodactylidae constitute the paratenic host groups frequently recorded in association with Centrorhynchus spp. sp. Aquarana catesbeiana is recorded for the first time as a host of Oxyascaris sp. and Catadiscus sp. on the American continent; larvae of Acuariidae gen. spp, Spirocamallanus sp. and Spiroxys sp., Gyrinicola chabaudi, Haematoloechus floedae and Centrorhynchus sp. in South America; and Falcaustra sp. in Brazil. In this context, the study expands knowledge about the helminth fauna of A. catesbeiana frogs and tadpoles in introduced areas. Further studies are needed to expand knowledge of the helminth assemblage, as well as the parasite-host relationship of A. catesbeiana in ecosystems where it is an invader.