Toxicity of tobacco dust to freshwater snails (Planorbella trivolvis) and channel catfish (Ictalurus punctatus)

Tobacco dust is a waste product of the tobacco industry and has been suggested as a molluscicide for aquaculture production. Snails serve as a required intermediate host for a number of trematode parasites. If snails can be eliminated using a molluscicide then aquaculture producers could effectively minimize parasitic infections of trematodes in their fish stocks by breaking the trematode life cycle. Four types of tobacco dust were evaluated as a potential molluscicide including burley (8200 μg/g nicotine), flue-cured (7200 μg/g nicotine), truck burley (4400 μg/g nicotine), and truck flue-cured (3900 μg/g nicotine). Ramshorn snails (Planorbella trivolvis), a common snail found in freshwater aquaculture ponds, were exposed to various concentrations of each type of tobacco dust over a three day period. Test concentrations included of 0 g/L tobacco dust and concentrations of 0.05, 0.25, 0.50, 1.0, and 2.5 g/L tobacco dust. Flue-cured and burley tobacco dust were more toxic compared to truck-flue-cured and truck burley tobacco dust. Tests on channel catfish (Ictalurus punctatus) were also performed at the same concentrations that were evaluated for snails. A dose between 0.5 to 1.0 g/L tobacco dust was effective in killing 100% of the snails within three days. In other experimental trials, there were no mortalities or histological evidence of effects on catfish at either of the 0.50 and 1.0 g/L tobacco dust concentrations over a 21 day trial. For the ramshorn snails, LC50 (lethal concentration to kill half of the snails) values were estimated to be 8.31, 2.58, and 1.73 mg/L nicotine for 24, 48, and 72 h exposure times, respectively. LC99 (lethal concentration to kill 99% of the snails) values were estimated to be 16.5, 8.35, and 5.41 mg/L nicotine for 24, 48, and 72 h exposure times, respectively.