The presence of high numbers of empty shells in anthropogenic habitats is insufficient to attract shell adopters among the insects

Abstract

Abstract Terrestrial snail shells can be considered partial resources for insects, and as such, the expansion of numerous snail species to anthropogenic habitats makes them increasingly available. Here, we address for the first time a complete profile of insects that use empty terrestrial snail shells during the winter period in Central Europe. The specialisation for shells made by certain snail species was uncommon; however, a number of species showed significant preferences for certain shell types. We found that the presence of empty snail shells in anthropogenic habitats drives the presence of many empty snail shell adopters in these habitats. Nevertheless, the increased availability of snail shells proved to be insufficient for a transition of all the species of snail shell adopters from natural to anthropogenic habitats. The avoidance of anthropogenic habitats among snail shell adopters was particularly distinct in species that use them only as a winter retreat but which require additional feeding and breeding resources, such as the true bugs. The availability of snail shells is thus a pre‐requisite of the presence of specialised snail shell adopters but is not necessarily sufficient to establish their presence in the respective habitat.