The Effect of Trematodes on Fecundity of Viviparidae

Abstract

The effect of trematode infection on fecundity of two species of Viviparidae, Viviparus viviparus and V. contectus is studied for the first time. The effect of Neoacanthoparyphium echinatoides trematode on the snail fecundity depends on the fluke’s life stage (parthenitae, cercariae, metarcercariae). The parthenogenetic life stages of trematodes significantly reduce fecundity of Viviparidae, because the snail as an intermediate host provides both the distribution and development of the parasite at great energy cost to itself. The flukes castrate their host obtaining an energy-rich trophic niche ensuring their subsequent development. Metacercariae, parasitizing in the snail, do not effect reproduction of the host population. To them, Viviparidae are only reservoirs which is not associated with energy costs.