The impact of diet treatment on reproduction and thermophysiological processes in the land snails Cornu aspersum and Helix pomatia

Abstract

Resource acquisition and allocation is a basic task of all animals. Organisms often encounter environmental heterogeneity in space and time, and may adapt their life histories that have been described as heritable set of rules determining allocation to growth or storage for survival versus reproduction. In Cornu aspersum reproductive strategy depended on seasonal time constraints and investment in reproduction was influenced by the energy available in the environment. Nutrients available in food, like lipids, were deposited in eggs, and a mixed calcium source affected the thickness of egg shell. This might enhance offspring survival. Bacteria in food or soil could be responsible for low supercooling ability and might persist during hibernation in the gut. In Helix pomatia that is used recently in low input snail farms in Germany to maintain this endangered species as a regional specialty under the name Albschneck®, showed low reproductive success even with high energy food compared to an Italian farm population. Helix pomatia preserved a rich bacterial community in the gut probably with ice nucleating bacteria and accumulated cryprotectants, like amino acids, triglycerides and glycerol, to enhance cold hardiness during hibernation. However mortality could be related to perpetual physiological adjustments to high temperature variations and extreme weather situations like dryness, but also be due to limited resource allocation to survival maintaining processes. Protection measures of this species should therefore include the preservation of refuge possibilities in the natural or artificial habitat.