Helminth community structure in the Argentinean bufonid Melanophryniscus klappenbachi: importance of habitat use and season

Abstract

The goal of this study was to evaluate the relative influence of terrestrial habits, season, and host body size on the species richness and abundance of helminth parasites in the toad Melanophryniscus klappenbachi, for which a greater abundance of nematode parasites was expected. A total of 90 toads were collected in the Chaco Province, Argentina. The helminth community found in infected toads included 17 taxa and was dominated particularly by larval parasites. Contrary to our expectations, nematode species showed lower values of infection parameters. Infected toads harbored a maximum of seven species, and the mean helminth richness was 3.16 ± 1.66 species per infected toads. Season played a significant effect on determining the species richness and abundance of the parasite infracommunity. Similarly, the prevalence of infection of several helminth species (8/47%) varied greatly over time. Host body size was the main factor in determining the infrapopulation structure of helminth parasites. Species richness was significantly and negatively correlated with host body size. Strong associations were observed mainly between larvae of some species. The transmission strategies of parasites suggest that this bufonid acquires infections through direct contact with larval parasites from aquatic and terrestrial habitats and by ingestion of infective larvae. The characteristic of the host tegument, such as the presence of alkaloids, could significantly contribute to the low occurrence of infection by skin-penetrating nematodes. Results also showed that diets and mobility of the host and the local microhabitat conditions play an important role in parasitic infections of toads.

Influence of temporal variation and host condition on helminth abundance in the lizard Tropidurus hispidus from north-eastern Brazil

“…Because some insects used as intermediate hosts exhibit seasonal variation in their abundance, the composition and establishment of heteroxenic helminth species can also be affected (Vasconcellos et al, 2010). We did not observe either temporal variation or differences in the reproduction period in the Atlantic Forest, so the variation found in the helminth populations here may be a consequence of other factors, such as habitat use and/or type of prey ingested (Roca et al, 2005;Hamann et al, 2006Hamann et al, , 2014Brito et al, 2014b). Also, the ontogeny and diet of the host determined the helminth assemblage in T. torquatus in the Atlantic Forest (Pereira et al, 2013), and the type of soil and fauna (eggs, predators or parasite larvae) can also affect the reproduction and survival of parasites (Harwood, 1936;Thieltges et al, 2008), showing effects on their abundance in the definitive host(s) (Harwood, 1936).…”

Helminth communities from amphibians inhabiting agroecosystems in the Pampean Region (Argentina)

“…Differences in size, reproductive behaviour, microhabitat preference and hormonal levels related to sex, can affect the exposure of amphibians to the infective stages of parasites. This could be due to a larger colonization area (more space and resources for larger amphibians) or for a longer exposure time, for example, when males vocalize from water during the reproductive periods (Aho, 1990;McAlpine, 1997;Hamann et al, 2006aHamann et al, , b, 2012Hamann et al, , 2013Hamann et al, , 2014b. For just over a decade, and with the establishment of the environmental parasitology as a discipline, emphasis has been placed on the role of parasites as indicators of environmental changes, demonstrating signifi cant effects…”

Diversidad de la helmintofauna de anuros de la región pampeana: un estudio comparativo en ambientes antagónicos

“…Gutierrez 1945;Suriano 1970;Combes & Laurent 1974;Ostrowsky de Nuñez 1978Mordeglia & Digiani 1998;Ramallo et al 2007;Arredondo et al 2009;Gonzalez Rivas et al 2012;Draghi et al 2015) y compendios o "checklists" (Lunaschi & Drago 2007;. En los últimos años, se ha avanzado notablemente en estudios de índole ecológica en la provincia de Corrientes (Kehr & Hamann 2003;Hamann et al 2006a;2006b;2012;2013a;2013b;2014a, 2014b. Aun así, existen géneros y especies de anfibios (p. ej.…”

“…La estacionalidad, por su parte, ha sido identificada como un factor importante regulando la estructura de las comunidades parásitas en anfibios hílidos (Hamann 2006;Hamann et al 2004;, leptodactílidos (Hamann et al 2012) y bufónidos (Hamann et al 2014b) de la región Neotropical. En este sentido, H. pulchellus posee picos reproductivos luego de las precipitaciones que ocurren durante la primavera y fines de verano, pero según nuestra experiencia en el campo es bastante común la observación de amplexos durante todos los meses del año.…”

“…Entre las características biológicas propias de los hospedadores, al sexo ha sido listado como un factor que puede influenciar en el número y abundancia de especies parasitas en vertebrados (Poulin 1996). Asociado a ello, diferencias de tamaño, de comportamiento reproductivo y a nivel hormonal pueden influenciar la exposición de los anfibios a los estadios infectivos de los parásitos ya sea por una mayor superficie de colonización, más espacio y recursos en el caso de anfibios de gran tamaño, o por un mayor tiempo de exposición, por ejemplo, en especies hospedadoras en las cuales el macho vocaliza desde el agua o en tierra en los períodos reproductivos (Aho 1990;McAlpine 1997;Hamann et al 2006Hamann et al , 2010Hamann et al , 2012Hamann et al , 2013bHamann et al , 2014b.…”