Trematodes and nematodes parasitizing the benthic insect community of an Andean Patagonian stream, with emphasis on plagiorchiid metacercariae

MARILUAN, GUSTAVO D.; VIOZZI, GUSTAVO P.; ALBARIÑO, RICARDO J.

INVERTEBRATE BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2012 vol. 131 p. 285 - 293

1077-8306

In freshwater systems, parasitological studies have mainly been carried out onvertebrates and molluscs, but little is known about parasites of aquatic insects. We describethe trematodes and nematodes parasitizing the benthic insects of an Andean Patagonianstream and the presence of parasites in the terrestrial adult stages. Members of 3 of 20insect taxa were found to be parasitized by larval nematodes, and members of six taxa har-bored metacercariae of digeneans. In benthic samples, chironomids, simuliids (Order Dip-tera), and baetids (Order Ephemeroptera) harbored mermithid larvae (Nematoda). ThestoneflyAntarctoperla michaelseni(Order Plecoptera), the caddisflySmicridea annulicornis(Order Trichoptera), a watersnipe fly (Order Diptera: Athericidae), and three species of lep-tophlebiid mayflies (Order Ephemeroptera) were parasitized by encysted plagiorchiid metac-ercariae (Order Plagiorchiida). Most metacercariae were found in the three species ofmayflies with prevalences ranging 15?63% and mean intensities ranging 1.2?4.9. Prevalencedeclined from summer to early winter, probably because of the emergence of infectednymphs and the recruitment of uninfected new cohorts. The imagos had live metacercariaewith higher prevalences and intensities of infection than nymphs. We suggest that theseplagiorchiids have an allogenic life cycle, involving a terrestrial definitive host.