Molluscicidal activity of Thai indegenous plant extract against Pomacea canaliculata

Abstract

Pomacea canaliculata (Lamarck) is one of a number of rice pests that causes serious problems because of rice field devastation. This study shows that the crude extracts of Thai indigenous plants have the capability of killing P. canaliculata (Lamarck). In toxicity tests, aqueous and ethanolic extracts of Thai indigenous plants were tested against P. canaliculata (Lamarck), 3-5 and 20-30 mm in size, and the toxicity was measured by LC50 at 72 h, with a 95% confidence limit. Results showed that for small snails (3-5 mm operculum diameter), strong activity was observed in aqueous extracts of Bougainvillea spectabilis, Calotropis gigantea and Croton tiglium and ethanolic extracts of Acacia concinna, Allamanda cathartica, Alpinia galanga, Bougainvillea spectablitis, Calotropis gigantea, Cosmos sulphureus, Lantana camara, Murraya paniculata and Sesbania grandiflora. When the toxicity of aqueous and ethanolic extracts of each plant was compared, ethanolic extracts of Alpinia galanga, Calotropis gigantea and Sesbania grandiflora had significantly greater toxicity than their aqueous extract, whereas the aqueous extract of Mimusops elengi had significantly greater toxicity than the ethanolic extract. For large snails (20-30 mm operculum diameter), strong activity was observed in aqueous extracts of Bougainvillea spectabilis and Calotropis gigantea, and ethanolic extracts of Alpinia galanga, Bougainvillea spectabilis, Croton tiglium and Sesbania grandiflora. When toxicity of aqueous and ethanolic extracts of each plants was compared, toxicity of the ethanolic extract of Croton tiglium was significantly greater toxicity than in the aqueous extract, whereas the aqueous extracts of Calotropis gigantea and Mimusops elengi had significantly greater toxicity than the ethanolic extracts. The Toxicity of various plant extracts with small and large snails was compared and aqueous extracts of Acacia concinna, Allamanda cathartica, Alstonia macrophylla, Bougainvillea spectabilis and Croton tiglium were more toxic to small snails than to large snails at a p-value <0.05. On the other hand, the ethanolic extracts of Calotropis gigantea, Cosmos sulphureus, Croton tiglium, Mimusops elengi and Murraya paniculata were more toxic for small snails than for large snails at a p-value <0.05. These findings suggest that isolation and purification of the active ingredients in these plants and more field studies should be done in future research. © Global Science Publications.