Toxicological evaluation of three methods of applying Rhizophora mangle on Galba cubensis (Mollusca: Gastropoda: Lymnaeidae)/Evaluación toxicológica de tres métodos de aplicación de Rhizophora mangle sobre Galba cubensis: (Mollusca: Gastropoda: Lymnaeidae)

Abstract

The molluscicidal e cacy of Rhizophora mangle on Galba cubensis was evaluated through three bioassays: two using aqueous extracts, one raw method extract (RME) and the other infusion method extract (IME), and direct application of powder (DAP). A completely randomized experimental design with three treatments, a control and ve replicates was used. LD50 and LD90 were determined using Probit-Log software. RME was used at 500, 400, 333 and 289 g L−1 concentrations; IME at 50, 25, 12.5 and 6 g L−1 ; and DAP extract at 0.540, 0.270 and 0.135 g. IME residence time and toxicity at 50 g L−1 in the substrate were also determined. We recorded 96, 80, 76, and 59 % cumulative mortalities with RME at 500, 400, 333, and 286 g L−1 concentrations, respectively; LD50 was 261.4 g L −1 and LD90, 442.79 g L−1 . For IME, it was 100, 94, 90 and 16 % for the concentrations of 50, 25, 12.5 and 6 g L −1 ; LDL50 was 8.57 g L−1 and LD90, 15.83 g L−1 . Mortalities with DAP extract were 70, 58, and 22 % at the 0.540, 0.270 and 0.135 g concentrations respectively, none of which reached LD90 and only the 0.540 g concentration reached LD50. IME residence and toxicity at 50 g L−1 decrease signi cantly after eight hours.

Keywords

• Molluscicidal
• mangrove
• Galba Cubensis