The population dynamics of Lymnaea columella in pastures was studied for a period of 6 years in dairy farms positive for Fasciola hepatica. This research was developed in the municipalities of Piquete and Redenção da Serra, both in the State of São Paulo. The results obtained were different for each farm, revealing that the populating dynamic of molluscs is closely related to climatic and ecologic factors, such as rainfall, temperature and biotop. In the municipality of Piquete, the increase in variation of the population density fluctuated in direct relationship to the decreasing of temperature and rainfall, being the largest number of molluscs captured during the dry period of the year, from May to October. On the other hand, in the municipality of Redenção da Serra, the high organic matter content in the biotop was responsible for the capture of the largest number of molluscs in the period of January to March, which corresponded to the period of high temperature and rainfall.
Population dynamic; Lymnaea columella; Fasciola hepatica
