The ecology of Lymnaea tomentosa (Pfeiffer 1855) in South Australia.

Abstract

The distribution of Lymnaea tomentosa, the intermediate host of Fasciola hepatica Linnaeus, in Australia is described and studies of its ecology in two separate areas represented by (1) streams, associated springs and swamps, and (2) the unique habitats along the margins of the Murray lakes, are reported. The relative density of snail populations in both of these areas was recorded over 4 yr and the fluctuations in population were shown to be related to factors controlling the presence of water in the habitat, water temperature, and the occurrence of a native predatory fly (Dichaetophora biroi Kertesz). Although the fly larvae can wipe out snail populations, the particular circumstances existing in South Australia suggest that this native species is unlikely to be a useful biological control agent. However, the practical importance of flies as predators on snails in irrigation areas should not be discarded.