Interaction Between The Intermediate Host Of Schistosomiasis In Brazil, Biomphalaria Glabrata (Say, 1818) And A Possible Competitor, Melanoides Tuberculata (Müller, 1774): A Field Study

The snail Melanoides tuberculata has been used successfully in the control of Biomphalaria glabrata, intermediate host of Schistosoma mansoni. Melanoides tuberculata has been introduced in Brazil, but its effects on populations of B. glabrata have not yet been evaluated in the field. Here we describe the population dynamics of B. glabrata before and after the invasion by M. tuberculata in an irrigation channel in the municipality of Sumidouro, Rio de Janerio. The abundance of B. glabrata varied seasonally according to rainfall until the period of invasion by M. tuberculata. After this period, the abundance of B. glabrata declined steadily. The population of M. tuberculata dispersed quickly along the irrigation channel, reaching to 7053 individuals/m2. In areas of recent invasion, small individuals dominated the population of M. tuberculata. This snail could be controlling the population of B. glabrata by chemical interaction, resource competition, or apparent competition through facilitation. However, its introduction and use to control B. glabrata must be considered with caution because the mechanisms of the interaction are not clearly understood.