Abstrakt
Exotic invasive plants are known to decrease mollusc species richness and also abundances of many snail species. However, there is not much evidence on how invasive plants influence snail trophic behaviour.
In this study, food preferences of alluvial land snails for invasive plants were studied. Two snail species (Succinea putris and Urticicola umbrosus) that commonly climb up invasive plants were chosen for food preference experiments.
The five most widespread exotic plant species invading river floodplains in Central Europe (Impatiens glandulifera, Helianthus tuberosus, Fallopia japonica, F. sachalinensis and F. bohemica) and one native species (Urtica dioica) were chosen as food for the snails. Results of the study confirmed a broadly accepted opinion, that land snails prefer senescent to fresh plant material.
The climbing efforts of the alluvial snails is therefore not for the purpose of foraging. The most important factors for snail food preferences were plant species identity and leaf condition.
The exotic plants were consumed to different extent, probably due to differences in defence mechanisms. The highest consumption was recorded for H. tuberosus and U. dioica, which are protected on their surface by trichomes.
Plants of the genus Fallopia, containing various secondary metabolites and high content of lignin, were mostly rejected. The native food source U. dioica did not change the preferences of the land snails when offered together with the invasive plants.