A small number of workers with specific personality traits perform tool use in ants.

István Maák,Garyk Roelandt,Patrizia D'Ettorre

doi:10.7554/elife.61298

Abstract

Ants use debris as tools to collect and transport liquid food to the nest. Previous studies showed that this behaviour is flexible whereby ants learn to use artificial material that is novel to them and select tools with optimal soaking properties. However, the process of tool use has not been studied at the individual level. We investigated whether workers specialise in tool use and whether there is a link between individual personality traits and tool use in the ant Aphaenogaster senilis. Only a small number of workers performed tool use and they did it repeatedly, although they also collected solid food. Personality predicted the probability to perform tool use: ants that showed higher exploratory activity and were more attracted to a prey in the personality tests became the new tool users when previous tool users were removed from the group. This suggests that, instead of extreme task specialisation, variation in personality traits within the colony may improve division of labour.

Highlights

Tool use is a widespread phenomenon within the animal kingdom (Shumaker et al, 2011; Sanz et al, 2013) and new examples of animal tool use are regularly discovered, such as recently in pigs (Root-Bernstein et al, 2019) and seabirds (Fayet et al, 2020)
In Experiment 3, we studied the possible link between individual personality traits and tool use
We studied tool use behaviour at the individual level in Aphaenogaster senilis to determine whether any forager that knows the location of the food and the tools puts the two together, or if it is an attribute of a subset of workers

Summary

Introduction

Tool use is a widespread phenomenon within the animal kingdom (Shumaker et al, 2011; Sanz et al, 2013) and new examples of animal tool use are regularly discovered, such as recently in pigs (Root-Bernstein et al, 2019) and seabirds (Fayet et al, 2020). Among the best described examples is the use of debris to transport liquid food by some species of ants (Morrill, 1972; Barber et al, 1989), in particular, several species of the genus Aphaenogaster (Fellers and Fellers, 1976; Tanaka and Ono, 1978; McDonald, 1984; Agbogba, 1985). Workers of these species are characterised by the lack of a distensible crop and by a chitinous gaster, preventing the transportation of large amounts of liquid food inside their bodies, a feature common in many other ant species (Holldobler and Wilson, 1990; Davidson et al, 2004). Workers forage individually mostly on the ground level and can cover large areas in habitats with scarce food

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