The molluscicidal effects of Hyptis suaveolens on different stages of Bulinus globosus in the laboratory

Abstract

The molluscicidal effect of the ethanolic extract of the plant Hyptis suaveolens was evaluated against different stages: eggs, juveniles and adults of the freshwater snail Bulinus globosus. Ten healthy one week old juveniles were exposed to different concentrations of the extract for 3 h, while three to four weeks old snails and the adults were exposed for 24 h. The egg masses were exposed for seven days. The mortality rates varied with concentrations and time of exposure. The LC₅₀ values for the eggs, of one week old juveniles, three to four week old immature snails and the adult snails were 0.614, 0.196, 0.161 and 0.077 ppm, respectively. The corresponding LC₉₀ values were 0.796, 0.353, 0.274 and 0.467 ppm, respectively. The results showed that the egg stage of B. globosus was the most resistant to the ethanolic extract of H. suaveolens.

Key words: Hyptis suaveolens, Bulinus globosus, mortality rate, LC₅₀ and LC₉₀.