Impact of desiccation on biology of Biomphalaria alexandrina and Bulinus truncatus snails

ABSTRACT

Biomphalaria alexandrina and Bulinus truncates snails were exposed to either complete or partial desiccation. Complete desiccation was carried out in dried plastic jars, while in partial one, the snails were exposed on filter paper saturated with dechlorinated and chlorinated water. Desiccation periods were 1 or 3 days, followed by recovery [1, 4, 6 and 8 days]. This technique was continued throughout 6 weeks for B. truncates and 18 weeks for B. alexandrina. Also, the hatchability of eggs laid by desiccated B. alexandrina eggs was evaluated. All treatments of both partial and complete desiccation decreased the survival and net reproductive rates of B. alexandrina and B. truncates snails. The net reproductive rates for snails partially desiccated for 24hr, followed by 6 days of recovery were reduced by 72.3% and 57.9% for B. alexandrina and B. truncates, respectively. Moreover, elongation of partial desiccation to 3 days, followed by 4 days of recovery highly suppressed this parameter for B. truncates to be 1.68 compared to 13.29 for control groups as well the life span of desiccated snails was shortened. In addition, B. truncates could not survive after 3 days of complete desiccation followed by 4 days of recovery, while only 7% of B. alexandrina survived at the 6th week of the test. Data also indicated that hatchability of B. alexandrina eggs obtained from snails exposed to both types of desiccation was not approximately affected, but the hatchability period was elongated in some treatments