Principal factors involved in the settlement of Biomphalaria glabrata (Say, 1818), snail intermediate host of schistosomiasis in Guadalupe, Six biotopes of Biomphalaria glabrata, the snail interm ediate host of schistosom iasis in Guadalupe, w ere investigated during one annual cycle. These six biotopes included a pond, a freshwater m angrove, a stream , a mountain lake, a "microhabitat" and a canal. These six types of biotopes w ere characterized by various parameters w hose fluctuations

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... the m ain factors regulating the B. glabrata populations. The clim atic factors are essential in Grande Terre and resulted in an annual developm ent cycle w ell determ ined of all the aquatic com m unities. The biotic factors (Predation, com petition, parasitism ) are important in every type of biotope, in Grande Terre as w ell as in Guadalupe proper. In every type of biotope, anthropic factors are also im portant, but m ainly in canal nets which are the principal focus of human schistosom iasis. The chem ical factors them selves are less im portant.