Population growth rate of the parasitic rotifer Proales gigantea, and susceptibility to parasitization in the snail Lymnaea acuminata at different stages of embryonic development

Abstract

Developing eggs of the host snail Lymnaea acuminata were experimentally parasitized with the parasitic rotifer Proales gigantea to study the population growth rate of the parasite within the snail egg capsule and the susceptibility of the host eggs at different stages of embryonic development. The population growth rate of P. gigantea was 0.46 ± 0.07 individual−1 day−1 at the ambient temperature of 18–22 °C. Snail eggs were most susceptible to rotifer attack during the initial stages of development, becoming progressively more resistant after the ‘hippo’ stage. Yet, regardless of the stage of development, the host embryo was doomed to die without hatching even if one individual rotifer gained entry inside the egg capsule. The presence of P. gigantea within the parasitized egg capsules or in the mucilage had no effect on the developmental rates and hatching success of non-parasitized eggs within the same egg mass.