The influence of above-optimal constant temperatures on South African Biomphalaria pfeifferi (Krauss) (Mollusca: Planorbidae).

The effects of constant above-optimal temperatures on the hatching, growth, survival, fecundity and development of the ovotestis of Biomphalaria pfeifferi from Komatipoort, South Africa, have been studied and compared with observations reported on B. glabrata. While rates of gametogenesis at 25 degrees C and ambient temperature (mean 22-8 degrees C) were similar, they were slightly accelerated at 27 degreesC. Fecundity and survival at 27 degrees C were considerably reduced and at 29 degrees C hyperthermia was pronounced.