Possible competitive displacement of planorbids by Melanoides tuberculata in Minas Gerais, Brazil.

Several species of snails, including Pomacea haustrum, Marisa cornuarietis and Helisoma duryi, have been identified as probable competitors and/or predators of planorbid intermediate hosts of Schistosoma. During the last few years, studies carried out in the Caribbean region have shown reductions and even disappearances of populations of Biomphalaria glabrata and B. straminea in breeding places where the snail Melanoides tuberculata was introduced. Observations made over a period of 10 years in two lakes close to Belo Horizonte, MG, showed that there were marked reductions in autochthonous populations of B. glabrata and B. straminea after the arrival of M. tuberculata, both Biomphalaria species disappearing completely after eight years.