Helminthic infection in three native rodent species from a semiarid Mediterranean ecosystem / Infecção por helmintos em três espécies de roedores nativos em um ecossistema mediterrâneo

Abstract Helminth parasites are still not a well-known component of animal biodiversity. In this study, we describe and compare the endoparasite assemblages of three native rodent species from a semiarid Mediterranean ecosystem. A total of eight species of gastrointestinal helminth parasites were detected. The endoparasitic communities of the rodents Phyllotis darwini (5 species), Octodon degus (4 species), and Abrothrix olivaceus (3 species) were described in terms of their prevalence and mean abundance. In addition, endoparasite records by rodent species were submitted to rarefaction analyses to verify sampling robustness and used to compare richness and similarity among rodent species. O. degus presented the highest prevalence and parasitic load, but was of low diversity, while P. darwini presented the highest diversity, but had a low prevalence rate. Conversely, A. olivaceus presented the lowest prevalence and diversity. This study contributes to the existing knowledge of the endoparasitic fauna of rodent species from semiarid Mediterranean zones.

Resumo Os helmintos parasitas não são um componente ainda bem conhecido da biodiversidade animal. Neste trabalho, descreveu-se e comparou-se as redes de endoparasitas de três espécies de roedores nativos de um ecossistema mediterrâneo semiárido. No estudo foram detectadas um total de oito de espécies de helmintos gastrointestinais parasitas. As comunidades endoparasíticas dos roedores Phyllotis darwini (5 espécies), Octodon degus (4 espécies) e Abrothrix olivaceus (3 espécies) foram descritas por meio da sua prevalência e abundância média. Além disso, os registros de endoparasitas achados nas diferentes espécies de roedores foram submetidos a uma análise de rarefação para verificar a robustez da amostragem, e utilizados para comparar a riqueza e a similaridade entre espécies de roedores. Octodon degus apresentou a maior prevalência e carga parasitária, menor diversidade, enquanto P. darwini apresentou a maior diversidade, mas uma baixa prevalência. Porém, A. olivaceus apresentou a menor prevalência e diversidade de parásitas. Este estudo representa uma contribuição ao conhecimento da fauna endoparasitária das espécies de roedores próprias das zonas semi-áridas do Mediterrâneo chileno.

What does determine gonad weight in the wild kissing bug Mepraia spinolai

Female fecundity increases with body size in a variety of insects, but it is unknown if this generalization applies for kissing bugs. In this study, we evaluate whether gonad weight in the bloodsucking insect Mepraia spinolai correlates with body size, or determined by nutrition or developmental time. We found that the investment on reproductive tissue correlates positively and significantly with body size and with the amount of ingested blood by female insects along their lifespan. Total molting time did not significantly affect gonad weight. We suggest that under optimal feeding conditions M. spinolai females could express their maximum reproductive potential.

DNA evidence of Trypanosoma cruzi in the Chilean wild vector Mepraia spinolai (Hemiptera: Reduviidae)

Molecular evidence showed 46.2 percent of Trypanosoma cruzi infection in Mepraia spinolai insects from North-Central Chile, which is significantly higher than previous reports of up to 26 percent by microscopic observation. Our results show similar infection levels among nymphal stages, ranging from 38.3 to 54.1 percent, indicating that younger nymphs could be as important as older ones in parasite transmission. A cautionary note must be stressed to indicate the potential role of M. spinolai in transmitting T. cruzi in country areas due to the high infection level detected by molecular analysis.

Abundance of Mepraia spinolai in a Periurban Zone of Chile

Mepraia spinolai is a silvatic species of Triatominae which prefers microhabitats near to or in rock piles. It is also able to maintain similar or higher size populations near houses. The density of bugs in quarries near Santiago, Chile, differed within microhabitats and varied significantly within sites according to season. M. spinolai was not found in sites characterized by human perturbation of quarries. Our results confirm M. spinolai as a silvatic triatomine whose importance as a vector of Chagas disease will depend on contact with humans. This could occur if the habitats where populations of this species are found become exploited for the building of urban areas