Field work research on population dynamic of snails from the
regions of Belo Horizonte and Lagoa Santa give much information about
interactions among two or more species of mollusks: Pomacea haustrum
, B. tenagophila, B. straminea and Melanoides
. Data ranging from two years to several decades ago
suggest that the Pampulha reservoir is like a cemetery of B. glabrata
and B. straminea, species that coexist for more than 14 years in a
small part of a stream, whereas only B.glabrata lives in
all the streams of the basin. In the last ten to twenty years B.
tenagophila has coexisted with P. haustrum and M. tuberculata in
the Serra Verde ponds and in the Pampulha dam. However these species
have not settled in any of the brooks, except temporarily. The data
suggest that the kind of biotope and the habitat conditions
are decisive factors for the permanence of each species in
its preferencial biotope.
B. glabrata, natural from streams and riverheads, quickly
disappears from the reservoirs and ponds where it coexists with other
species for a short time, independently of the competitive process.
Competition needs to be better studied, since in Central America
and Caribean islands this kind of study has favored the biological
control of planorbid species.