Abstract
Ants occupy a great variety of habitats, perform essential ecological roles, and interact with a wide variety of other organisms. However, the interaction between ants and mollusks is a lesser-explored relationship that can be categorized into (a) ant predation on mollusks, (b) shell collection as hoarding behavior, (c) the use of shells for nesting, and (d) myrmecophilic relationships. This study reports new data about several interactions from accidental field observations, a quantitative analysis of the snail shells found in 16 Messor ant nest cleanings, and a qualitative analysis of 51 additional nests of different species. We found 1127 snail shells from 20 species, most of them belonging to juveniles of the Geomitridae and Helicidae families. Notably, Granopupa granum was the only species found alive in the collected material. Furthermore, in our qualitative assessment, we found 86.8% of the analyzed nests with shell remains in the nest cleanings of at least nine ant species. Additional observations revealed ants transporting both empty shells and live snails to the nest, some living snail species around the nest entries, and additional interactions. Our results may support cases of (a) predation of snails of certain species by ants, as many shells were found with perforations compatible with ant attacks and we have recorded direct predation, (b) the collection of empty shells to gather the body remains of snails as a trophic resource or for other purposes, and (c) the potential existence of more myrmecophilous snail species than currently known, capable of living in ant nests without being attacked, like Cecilioides acicula, Ferrussacia folliculum, or G. granum. Although more studies are necessary to understand the intriguing relationship between ants and snails, the study of ant nest wastes can also become a valuable tool for detecting rare native micromollusc, as well as invasive, non-native, and aquatic species.