Cercarial productivity of redial generations in single-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or Fasciola hepatica

Single-miracidium infections of Lymnaea truncatula with Paramphistomum daub neyi or with Fasciola hepatica were carried out under laboratory conditions to count free rediae, their germinal embryos, and to determine the cercari al productivity of each redial generation. In snails infected by P. daubney i, the cercariae were produced by the first (8.7 cercariae per redia) and s econd (8.9 per redia) generations. At day 63 post-exposure, they correspond ed, respectively, to 53.9% and 46.1% of cercariae produced by all rediae. I n snails infected by F. hepatica, the majority of cercariae were produced b y the R2a group (18.2 cercariae per redia) and corresponded to 66.0% of cer cariae produced all rediae. The cercariae produced by the other redial grou ps were more limited in number: 17.5 per redia in the R1b group (28.7%) and 2.0 per redia in the R2b/R3a group (5.3%). Cercarial productivity of P. da ubneyi until day 63 post-exposure was more limited in number than that of F . hepatica: a total of 145 cercariae per snail versus 427 per snail.