Physiological studies on Biomphalaria alexandrina and Bulinus truncatus, the snail vectors of Schistosommiasis

Summary

The Warburg's manometric technique was used to measure the rate of oxygen consumption of the second generation of laboratory-reared snails, Biomphalaria alexandrina and Bulinus truncatus at two temperatures of 25° and 30°C. The individual weight of the experimental snails ranged between 40 and 78 mg for B. alexandrina, between 60 and 90 mg for B. truncatus.

At 25°C, the uninfected snails B. alexandrina consumed oxygen at an average rate of 0.096 ± 0.020 ml/g wet wt/hr. The rate of oxygen consumption increased to an average of 0.147 ± 0.008 ml/g wet wt/hr for uninfected snails maintained at 30°C (about 53 per cent increase). The average RW value for uninfected snails maintained at 25°C was 0.80.

The snail Bulinus truncatus showed higher oxygen requirements than the snail Biomphalaria alexandrina. At 25°C, it consumed oxygen at an average rate of 0.124 ± 0.016 ml/g wet wt/hr. At 30°C, the rate of oxygen consumption reached a value of 0.220 + 0.006 ml/g wet wt/hr. The average RQ for Bulinus truncatus maintained at 25°C was 0.87.

The rate of oxygen consumption of the schistosome — infected Biomphalaria alexandrina snails, maintained at 25°C decreased to an average rate of 0.059 ± 0.010 ml/g wet wt/hr, (an average of 39 per cent decrease). The respiratory quotient (RQ) also decreased to an average value of 0.58. Further research is suggested to clarify the metabolism of both schistosome-infected and uninfected snails.