RESUMO
Knowledge of population dynamics of parasites in freshwater snails from South America is scarce. The objective of the present study was to describe the infection dynamics of larval digeneans in the planorbid snail, Biomphalaria peregrina , during 2 sampling periods in a Patagonian temporary pond. In total, 1,003 snails were examined. Rediae of Notocotylus biomphalariae and Echinoparyphium sp., sporocysts of Cotylurus sp., and metacercariae of the 2 latter species were found. The overall prevalence was significantly higher in the second sampling period, always as single-species infections in the hepatopancreas. The presence of larvae in the first sampled snails of the second hydroperiod indicated that parasitized snails survive drought. Both species exhibited different seasonal prevalence patterns, with Echinoparyphium sp. present in all sampling months. Metacercariae of Echinoparyphium sp. occurred in the heart and kidney, and those of Cotylurus sp. between organs. No significant differences in overall prevalence of metacercariae were found, and a progressive rise in prevalence from spring to summer for both species was observed. Almost all size classes of B. peregrina were infected with metacercariae of both species, but rediae and sporocysts were present only in snails larger than 3.1 mm. The predictability of the hydroperiod year after year, the tolerance of B. peregrina to drought, and the survival of infected specimens allows the parasite community to show a similar pattern of infection over time. This is the first study in Argentina analyzing the infection dynamics of digeneans of a pulmonate snail from a temporary pond.
Assuntos
Biomphalaria/parasitologia , Trematódeos/fisiologia , Animais , Argentina , Vetores de Doenças , Echinostomatidae/fisiologia , Água Doce , Coração/parasitologia , Hepatopâncreas/parasitologia , Interações Hospedeiro-Parasita , Rim/parasitologia , Estações do Ano , TemperaturaRESUMO
A new species, Stephanoprora aylacostoma is described and its life cycle was resolved experimentally. The prosobranch snail Aylacostoma chloroticum Hylton Scott, collected in the Yacyretá dam, Province of Misiones, Argentina, was found naturally infected with large-tailed cercariae possessing a prepharyngeal body and corpuscles in the excretory system but lacking collar spines. Metacercariae, which encysted on the gills of experimentally infected fishes Cnesterodon decemmaculatus (Jenyns) and Poecilia reticulata (Peters) (Poecilidae), developed collar spines after 10 days. Tetragonopterid fishes Moenckhausia dichroura (Kner), Astyanax erythropterus (Holmberg) and Hyphesobrycon serpae (Durbin in Eigenmann) were found infected naturally. Sexually mature adults were recovered from domestic chicks at day 7 post-exposure. Eggs shed in chick faeces developed to miracidia within 13-15 days; sporocysts were found on the gills of snails. The new species differs from other species of the genus in its larger eggs, in the smaller, slender body and smaller collar spines of the adult and in the morphological and biological features of the larval stages.
Assuntos
Galinhas/parasitologia , Echinostomatidae/crescimento & desenvolvimento , Peixes/parasitologia , Interações Hospedeiro-Parasita , Estágios do Ciclo de Vida , Caramujos/parasitologia , Animais , Argentina , Echinostomatidae/anatomia & histologia , Echinostomatidae/classificação , Echinostomatidae/fisiologia , Fezes/parasitologia , Doenças dos Peixes/parasitologia , Brânquias/parasitologia , Contagem de Ovos de Parasitas , Doenças das Aves Domésticas/parasitologia , Infecções por Trematódeos/parasitologia , Infecções por Trematódeos/veterináriaRESUMO
During a survey of parasites of the Patagonian freshwater crab Aegla neuquensis neuquensis, its ectosymbiont Temnocephala chilensis was found parasitized with an echinostomatid metacercaria with 43 collar spines. Of the 414 T. chilensis collected, 106 were parasitized with metacercariae of Echinoparyphium sp. Ovigerous adults of E. megacirrus were obtained from domestic chicks experimentally infected with metacercariae obtained from temnocephalans. This is the first record of temnocephalans being parasitized by digeneans.