Some angles of the biology of Biomphalaria glabrata (Say, 1818) and Biomphalaria tenagophila (D'Orbigny, 1835) (Pulmonata, Planorbidae): I. Duration of the embryo period

Abstract

The incubation periods of Biomphalaria glabrata and Biomphalaria tenagophila were compared during one year, in the laboratory. The average time for eggs hatching was 7,6 and 8,0 days for Biomphalaria glabrata and Biomphalaria tenagophila, respectively; the difference was not significant at the 5% level. The fastest development of the eggs was verified in the summer when the average water temperature was approximately 28°C. The analysis of the correlation coeficient showed that the influence of temperature on the egg development period was not strong: Biomphalaria glabrata showed best correlation with minimum air temperature (36,2%) and with water temperature (36,0%), while Biomphalaria tenagophila correlated best with minimum air temperature (27,0%).