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 molluscs is a lesser-explored relationship
that can be categorized into a) ant predation on molluscs, b) shell
collection as hoarding behaviour, c) the use of shells for nesting, and
d) myrmecophilic relationships. This study reports new data about these
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
analysed nests with shell remains in the nest cleanings of ten 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 between snails and ants. 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,
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.