Tobacco dust: A novel molluscicide for aquaculture applications

Parasitic trematodes require an intermediate host, such as a freshwater snail, to complete their lifecycle. It has been suggested that tobacco dust, a by-product of the tobacco industry, could be an effective molluscicide option for the aquaculture industry. Thus, the eradication of snails by this potential molluscicide could effectively reduce parasitic trematodes. Four types of tobacco dust were evaluated as a molluscicide including burley (8200 mu g/g nicotine), flue-cured (7200 mu g/g nicotine), truck burley (4400 mu g/g nicotine), and truck flue-cured (3900 mu g/g nicotine). Common freshwater snails (Physa spp.) and daphnia (Daphnia magna) were exposed to various concentrations of each type of tobacco dust over a three day period. Test concentrations included 0 g/L tobacco dust as a control and concentrations of 0.05, 0.25, 0.50, 1.0, and 2.5 g/L tobacco dust. Tests on goldfish (Carassius auratus) were also performed for a 21 day period. For flue-cured and burley tobacco dust, a dose as low as 1.0 g/L tobacco dust was effective in killing 100% of the snails within three days. For snails, the calculated LC50 (lethal concentration to kill half of the snails) values using all five concentrations of tobacco dust and four types were estimated to be 6.51, 2.51, and 2.10 mg/L nicotine for 24, 48, and 72 h exposure times, respectively. Daphnia were most sensitive to tobacco dust. Less than 70% of daphnia survived for 24 h at 0.05 g/L, the lowest tobacco dust concentrations evaluated. For daphnia, LC50 values were estimated to be 0.92,