Abstract

Trumpet snails (Melanoides tuberculata) are an invasive species commonly found in waterways and aquaria through transfer from aquariums.^1–3 While industrial pesticides and disinfectants are effective euthanasia agents,³ these chemicals are not practical for small-scale use. The study objective was evaluation of immersion euthanasia methods using common household and clinical solutions in trumpet snails.

Snails (n=230, 7.58 mm ± 2.24 mm) were randomly group-exposed (n=5 or 10/group) via immersion to one of 18 solutions (flat or carbonated beer, 5% ethanol, 10% or 25% oral antiseptic solution, 0.1, 0.125, 0.2 or 0.4 g/L clove oil, 0.4, 0.8, 1 or 2 g/L tricaine methanesulfonate, or 5, 7.5, 10, 15, or 20% MgCl₂) by immediate or gradual (over 5 minutes) exposure for 2 or 24 hours. Individual response to stimuli was serially assessed by manipulation with a 25g needle. At end-exposure, snails were placed in dorsal recumbency in freshwater and monitored for 96 hours. Time to sternal recumbency was recorded and failure to do so was considered consistent with euthanasia.

Immediate or gradual exposure to 10% or 20% MgCl₂ or 0.4 g/L clove oil for 24 hours and gradual exposure to 0.2 g/L clove oil for 24 hours resulted in euthanasia in 100% of exposed snails. The remaining treatments produced partial or no mortality. Exposure to >7.5% MgCl₂ for 2 hours resulted in prolonged time to sternal recumbency (>24 hours).

Prolonged exposure to ≥10% MgCl₂ or ≥0.2 g/L clove oil may be effective for trumpet snail euthanasia.

Acknowledgments

The authors would like to thank the NCSU CVM Aquatics Team for providing the snails used in this study.

Literature Cited

1.  Barros MRF, Chagas RA, Herrmann M, Bezerra AM. 2020. New record of the invasive snail Melanoides tuberculata (Gastropoda, Thiaridae) – Ceara State, Brazil. Braz J Biol 80:368–372.

2.  McClure MR. 2021. Novel introduction for the invasive red-rim melania Melanoides tuberculata (Muller) in Southeastern Texas. Southwest Nat 64:232–235.

3.  Mitchell AJ, Hobbs MS, Brandt TM. 2011. 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. N Am J Fish Manag 27:1287–1293.