Table 1:
Comparison of cold tolerance strategies in three species of European Helicidae
| Parameter | Helix pomatia | Cornu aspersum | Cepaea nemoralis |
|---|---|---|---|
| Annual cycle | Hibernation: 5–6 months Aestivation: few days | Hibernation/aestivation: highly variable across Europe (6–0 months) | Hibernation: 5–6 months Aestivation: few days |
| Shell breadth | 30–50 mm | 25–40 mm | 18–25 mm |
| Cold-tolerance processes | Tc = −2°C (activity) Tc = −6°C (dormancy) LT50 = −10°C (2 h exposure) | Tc = −3°C (activity) Tc = −5°C (dormancy) LT50 = −10°C (2 h exposure) | Tc = −4°C (activity) LT50 = −10°C (2 h exposure in activity) Tc = LLT = −10°C (dormancy) |
| Cold-tolerance strategy | Partly freeze tolerant | Partly freeze tolerant | Partly freeze tolerant (activity)Freeze avoidant (dormancy) |
| Distribution | South-Eastern Europe to England and Scandinavia | North Africa to North Western Europe (The Netherlands, England) and eastwards to the Rhine Valley | Central Europe from Mediterranean to England and eastwards to Poland |
| Status | Protected in Europe (Appendix III, Bern Convention) | Invasive in North and South America, Australia, South Africa and New Zealand | Invasive in North America |
| References | Nietzke (1970); Lind (1988); Kerney and Cameron (1999); Nicolai et al. (2005, 2011, 2012a, 2015); Ansart et al. (2014); personal observation A.N. | Kerney and Cameron (1999); Ansart et al. (2001, 2002, 2010, 2014); Nicolai et al. (2005); personal observations A.A. and A.N. | Kerney and Cameron (1999); Ansart et al. (2014); personal observations A.A. and A.N. |
Abbreviations: LT50, lethal temperature for 50% of individuals; LLT, absolute lower lethal temperature; Tc, temperature of crystallization.