Evaluation of Molluscicidal Activity of Croton microstachyus and Cissus quadrangularis against Biomphalaria and Bulinus Species of Snails

Abstract

Aim: The study was carried out to investigate the molluscicidal activities of different solvent extracts of two Eritrean local plants, Croton macrostachyus and Cissus quadrangularis identified using ethno-botanical, pharmacological information and also traditional use gathered from traditional healers. Methods: Various solvent extract concentrations of leaves of Croton macrostachyus and Cissus quadrangularis leaves and seeds were tested for their molluscicidal activity against adult Biomphalaria species, the intermediate host of S. mansoni and Bulinus species, the intermediate host of S. haematobium and S. intercalates. The LC50 and LC90 were determined at 24 hours of exposure. Comparison of molluscicidal activity of the different solvent extracts within and among the plants was also done. The effect of the increase in exposure time (36 and 48 hrs) on molluscicidal activity of the plants with respect to each solvent extract was then assessed. Results and Discussion: Screening test results indicated that a significant molluscicidal activity ranging from 15.558 ppm to 289.689 ppm was found. Comparison of the solvent extracts also revealed that a significant difference was shown in all the three plant materials, with p-value less than 0.05. Half (50%) of the plant extracts were found to have a significant difference in their molluscicidal activity upon increase in exposure time (p<0.05). In general, comparison of the plant material extracts showed that Croton marostachyus seed has the highest molluscicidal activity. Conculision: From the observations, it is concluded that plants, Croton macrostachyus leaf, seed and Cissus quadrangularis leaf were found to have molluscicidal effect against Bulinus species and Biomphalaria species of snails. Crude extracts of these plants caused death of the snails at varying concentrations. The best results in terms of toxicity to the intermediate host snail were exhibited by Croton macrostachyus seed, followed by Croton macrostachyus leaf. Prolonging the time of exposure was also found to increase the killing ability on half of the plant extracts.