Molluscicidal activity of tabaco dust against the brackishwater pond snail Telescopium telescopium (Gastropoda: Potamididae)

Abstract

Telescopium telescopium, a molluscan potamidid snail thrives in the muddy substrates of brackishwater ponds in the Philippines. It occurs in considerable numbers but uncontrollable increases in its population poses serious threats to pond production. Tobacco dust is considered as a potential biomolluscicide that is able to control pond snail infestation. A short-term bioassay was conducted to know the effectiveness of tobacco dust as a molluscicide against T. telescopium by determining its median lethal concentration (LC50) after a period of 96 hours. Twenty-five telescope snails were subjected to varying concentrations of tobacco dust, from 0 to 1.0 kg/L at 0.2-kg increments. Three replicates were done for every treatment. Counting of dead snails was done after 48 and 96 hours of exposure. Snails exposed to varying concentrations of tobacco dust exhibited several defense mechanisms such as avoiding the toxic solution by crawling out of the area, closing their operculum and retracting their bodies toward their shell. Highest snail mortality was observed at the 1.0-kg/L treatment. After the 96-hr. exposure time, the concentration of tobacco dust that proves to be lethal to 50% of the snails was computed to be 0.5849 kg/L. Indeed, tobacco dust is an effective molluscicide against brackishwater pond snails, particularly T. telescopium.