Résumé
Life tables of several strains of Biomphalariea glabrata, B. alexandreina and B. straminea have been established under laboratory conditions and compared with that of Malanoides tuberculata, a prosobranch snail used as a competitor of snail vectors of schistosomiasis in experiments of biological control. Results indicate a grat range of intraspecific and interspecific variation within the Biomphalaria and a quite distinct demographic strategy of M. tuberculata.