In this line of research, the life cycle of Schistosoma mansoni is maintaned in Biomphalaria glabrata snails. The malacologycal survey in some regions of Minas Gerais State, effects of Avertmectins on freshwater snails, susceptibitlity to S. mansoni, and the search of some larval trematodes from several species of freshwater molluscs has been carried under laboratory conditions.