Interaction in the laboratory between Helisoma duryi, a possible competitor snail, and Biomphalaria pfeifferi, snail intermediate host of Schistosoma mansoni.

The planorbid snail, Helisoma duryi, has been proposed as a possible biocontrol agent against the intermediate host snails of schistosomiasis. In an attempt to evaluate the possible effect of interference between H. duryi and Biomphalaria pfeifferi, life-tables were compiled for these two snail species maintained both in the presence of each other and separately. The calculated population parameters indicated that H. duryi had a higher innate capacity of increase, net reproduction rate and finite rate of increase as well as a longer lifespan than the target species. However, the biological potential of B. pfeifferi was not influenced by the presence of H. duryi, and the latter appears to be unable to act as competitor against B. pfeifferi under similar prevailing conditions. It is possible that the situation might change under conditions of crowding and starvation.