The Effect of Chemical Treatments on Red-Rim Melania Melanoides tuberculata, an Exotic Aquatic Snail that Serves as a Vector of Trematodes to Fish and Other Species in the USA

Abstract

The red-rim melania Melanoides tuberculata, a subtropical and tropical snail, is a nonindigenous species that has become established and is spreading in the United States. Of concern is the potential of the red-rim melania to displace native snail populations and to transmit trematodes that cause serious problems. One of these, a fish gill trematode, Centrocestus formosanus, has negatively affected U.S. commercial and wild fish stocks, including some endangered species. The snail has an operculum that can protect it from desiccation and can remain viable for days on dry fisheries equipment. Thus, contaminated fisheries equipment is suspected as one of the ways the snail is being moved from place to place. A study was conducted to find chemical treatments that would kill 100% of the red-rim melania. Thirteen different chemicals and chemical combinations were evaluated at different concentrations and for various exposure periods. Roccal-D-Plus, Hydrothol 191, niclosamide, and Virkon showed promise in 24-h exposures at concentrations of 20 mg/L active ingredient (AI), 80 mg/L AI, 2 mg/L, and 1,600 mg/L AI, respectively. Additionally, Roccal-D-Plus killed all snails exposed to 2,000 mg/L for 1 h and to 600 mg/L for 16 h. Roccal-D-Plus has a history of use as a disinfectant for fishery equipment.