The characteristics of habitats colonized by three species ofLymnaea (Mollusca) in swampy meadows on acid soil : their interest for control of fasciolosis

Abstract

Malacological investigations were carried out in 53 meadows on acid soil to identify the characteristics of habitats colonizedby lymnaeid snails. These meadows are located in three different geographical districts (Basse-Marche, Monts d'Ambazac, Plateauxde la Vienne) in the Haute-Vienne Department (central France). Lymnaea truncatula lived at the distal extremity of opendrainage furrows ; L. glabra inhabited the middle part of furrows and L. palustris lived in the central ditch. The mean area of L.truncatula habitats ranged from 2.8 to 4.8 m² in relation to the district studied and was smaller than those of L. glabra (a meanof 3.6 to 7.2 m² ) and L. palustris (10.3 to 19.3 m²). Mean intervals between the sites occupied by L. truncatula and L. glabraranged from 6.3 to 12.3 m ; they were greater between the sites occupied by L. glabra and L. palustris (11.6 to 15.4 m). Finally,the mean densities of L. truncatula in June ranged from 11.4 to 19.8/m² in relation to the district studied ; those of L. glabra rangedfrom 22.6 to 27.0 snails/m², whereas in L. palustris, they ranged from 6.3 to 8.8 snails/m². The mean values of these first twoparameters were significantly lower in the habitats located in Monts d'Ambazac than those recorded in the two other districts. Implicationsof these results for fasciolosis control are discussed.