Effect of programmed circadian temperature fluctuations on population dynamics of Biomphalaria pfeifferi (Krauss)

Abstract

Until now all life-table studies on freshwater snails involving temperature as the variable factor have been conducted at constant temperatures. This study evaluates the differences between carefully programmed, cyclic, daily temperature fluctuations, namely 18 to 28°C and 20,5 to 25,5°C and a constant temperature of 23°C on the population dynamics of Biomphalaria pfeifferi (Krauss), an intermediate host snail of Schistosoma mansoni Sambon. Life-tables were compiled for cohorts of 25 snails each at each of the above-mentioned temperature regimes and the customary population parameters calculated for each cohort. The best results were obtained at the highest daily temperature fluctuation to which the snails were subjected during this investigation.