Cercarial productivity of Fasciola hepatica in Lymnaea truncatula during usual and unusual development of redial generations

Single-miracidium infections of Lymnaea truncatula by Fasciola hepatica wer e carried out to determine the cercarial productivity of each redial genera tion when the first-appearing mother redia (R1a redia) normally developed ( usual development of redial generations) or quickly died (unusual developme nt). In both developmental patterns of infection, the number of morulae was significantly higher in the second-appearing mother rediae (R1b group) tha n in either the daughter rediae from Rla rediae (R2a group) or the rediae f rom subsequent groups (R2b/R3a). The live R1a group did not produce cercari ae. The percentages of cereariae produced by the R1b, R2a, and R2b/R3a grou ps were 28.2%, 62.8%, and 8.9% when the development of redial generations w as usual. In contrast, in an unusual development, they were 69.3%, 20.3%, a nd 10.2%, respectively. Cercarial production until day 63 post-exposure was essentially provided by the R2a rediae, when the development of redial gen erations was usual, and by the R1b rediae when it was unusual.