Detection of habitats colonized by Omphiscola glabra (Gastropoda: Lymnaeidae) on acid soils using indicator plants

Abstract

The lymnaeid Omphiscola glabra is known to be an intermediate host in the life cycle of Fasciola hepatica and knowing its distribution in the field is important to determine that of the parasite. Looking at indicator plants has been proposed by several authors as one of the most practical ways of carrying out a malacological survey in pastures of a farm. Field investigations on 361 French farms breeding cattle or sheep on acid soils were thus carried out for 36 years in March or April to list indicator plant species in seven types of habitats colonized by O. glabra , and determine the characteristics of their habitats (area, snail density) for each indicator plant. Six plant species: Agrostis stolonifera , Dactylis glomerata , Glyceria fluitans , Juncus acutiflorus , Juncus effusus and Lotus uliginosus , were examined in 3137 snail habitats. J. effusus was the best indicator species to detect snail populations in five habitat types, while J. acutiflorus was the best indicator for snail populations living in spring heads. The other four plant species characterized only a few populations. Snail habitats detected with J. acutiflorus , J. effusus or L. uliginosus were significantly larger in area, while the density of overwintering snails was significantly lower in habitats with G. fluitans . These initial results suggest that J. effusus is a good indicator for the detection of O. glabra in the acid soils of central France. However, additional studies are required to test its limitations in the field.