Field observations on the population dynamics of Bulinus globosus, the intermediate host of Schistosoma haematobium in the Ifakara area, Tanzania.
The population dynamics of Bulinus globosus were studied in a stream and an adjacent pool near Ifakara, Tanzania. Experiments with caged snails were used to determine fecundity, hatching rates, growth and mortality. Growth and mortality rates were also estimated for the natural population from successive size frequency distributions. Oviposition began in snails as small as 6.6 mm and there was a positive correlation between the size of the snails at oviposition and the number of embryos per egg mass. Fecundity was season-dependent. In the pool, snail growth was constant throughout the year, while in the stream, growth was markedly reduced during the rainy season. Mortality rates correlated with fluctuations in snail population density and were highest during the rainy season and among young snails. The high intrinsic rate of natural increase observed for B. globosus enables it to exist in habitats which alternate frequently between favorable and adverse conditions.
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D000818:Animals; D002033:Bulinus / Q000254:growth & development / Q000469:parasitology / Q000502:physiology*; D004199:Disease Vectors; D005260:Female; D009026:Mortality; D010058:Oviposition; D011157:Population Dynamics; D012548:Schistosoma haematobium / Q000254:growth & development*; D012621:Seasons