Mathematical simulation of an aquatic snail population.

Techniques for controlling the intermediate snail hosts of schistosomiasis have had to be evaluated by field trials, since the complexity of snail population dynamics has so far made it impossible to predict the effects of these techniques and thereby avoid costly field testing.However, in laboratory studies with Biomphalaria glabrata it was found that the fecundity of these snails was directly proportional to F/NV, where F is the total amount of food in the habitat, N the number of snails, and V the volume of the habitat. The use of this fecundity variable together with data published on snail longevity and fecundity made it possible to construct a mathematical model of a snail population which may eventually be useful for evaluating snail control methods.For preliminary verification of the model, its predictions were compared with a published history of a population of Bulinus globosus in a small pond. The general agreement of the predicted and observed population data indicated that the basic structure of the model was sound.