Interaction between the intermediate host of F ascioliasis in T unisia, G alba truncatula and a possible competitor, M elanoides tuberculata ( M uller, 1774): a field study

The snail M elanoides tuberculata has been used successfully in the control of some snails, intermediate host of parasitosis. M elanoides tuberculata has been found in Tunisia, but its effects on populations of native snail have not yet been evaluated in the field. Our objective is to determine whether M . tuberculata competed with G alba truncatula , using a field study. Twelve monthly investigations were carried out along an irrigation system in A in S oltane's oasis (southwest of T unisia). Here, we describe the population dynamics of G . truncatula with and without M . tuberculata in two stations: a witness pilot station ( S 1), in which the snail lives alone, and an experimental station ( S 2), where two species live together. The abundance of G . truncatula varied according to subsistence or not of M . tuberculata . The number of annual generations is higher in S 1 (four generations) than S2 (two generations). In the absence of other molluscs or predators that can influence the density of G . truncatula and assuming that climatic factors are mitigated by the presence of an oasean microclimate, these results show that the mollusc M . tuberculata has a competition with the vector species of fluke.