In a behavioural bioassay, effluents from cigarette butts, cured tobacco and tree leaves differentially affect resting site selection in the land snail Cornu aspersum

Abstract

ABSTRACT Cigarette butts (CBs) contain a plethora of chemicals, including many that are toxic. Although numerous studies have demonstrated the toxicity of CBs to aquatic organisms, there is less evidence that terrestrial organisms are severely impacted. Because CBs are commonly discarded on the ground, ground-dwelling organisms such as land snails may be especially affected. Many land snails are generalist detritivores/herbivores and ingest a variety of plant secondary compounds as they feed. This evolutionary exposure may render CBs (made principally of cured tobacco leaves) less toxic to these land snails than CBs are to less exposed aquatic animals. We investigated this possibility of reduced effects using a new behavioural assay to test the choice of ‘flavoured’ vertical resting sites in the land snail Cornu aspersum, which commonly rests on upright surfaces. In four experiments, regions of container walls were coated with different concentrations of CB and cured tobacco effluents, and effluents from three tree species and cured tobacco. Snails avoided high CB and tobacco effluent concentrations, which is consistent with toxicity. However, snails preferentially rested on dilute concentrations of both CBs and tobacco. Preference among tree leaf effluents was less evident, with a trend towards snails preferring the more readily eaten maple than the less readily eaten oak. Selection of the preferred tobacco concentration did not differ from that of tree leaves, indicating that C. aspersum was not repelled by dilute tobacco effluent. These results indicate that compounds leaching from discarded CBs may have little effect on snails and perhaps other soil organisms under environmentally realistic conditions.