ORIGINAL PAPER Nesting habits shape feeding preferences and predatory behavior in an ant genus Alain Dejean & Nicolas Labrière & Axel Touchard & Frédéric Petitclerc & Olivier Roux Received: 6 December 2013 /Revised: 2 February 2014 /Accepted: 4 February 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract We tested if nesting habits influence ant feeding preferences and predatory behavior in the monophyletic genus Pseudomyrmex (Pseudomyrmecinae) which comprises terres- trial and arboreal species, and, among the latter, plant-ants which are obligate inhabitants of myrmecophytes (i.e., plants sheltering so-called plant-ants in hollow structures). A cafete- ria experiment revealed that the diet of ground-nesting Pseudomyrmex consists mostly of prey and that of arboreal species consists mostly of sugary substances, whereas the plant-ants discarded all the food we provided. Workers forage solitarily, detecting prey from a distance thanks to their hypertrophied eyes. Approach is followed by antennal con- tact, seizure, and the manipulation of the prey to sting it under its thorax (next to the ventral nerve cord). Arboreal species were not more efficient at capturing prey than were ground- nesting species. A large worker size favors prey capture. Workers from ground- and arboreal-nesting species show several uncommon behavioral traits, each known in different ant genera from different subfamilies: leaping abilities, the use of surface tension strengths to transport liquids, short-range recruitment followed by conflicts between nestmates, the consumption of the prey’ s hemolymph, and the retrieval of entire prey or pieces of prey after having cut it up. Yet, we never noted group ambushing. We also confirmed that Pseudomyrmex plant-ants live in a kind of food autarky as they feed only on rewards produced by their host myrmecophyte, or on honeydew produced by the hemipterans they attend and possibly on the fungi they cultivate. Keywords Ant genus Pseudomyrmex . Arboreal and ground nesting . Feeding preferences . Myrmecophytism . Predation Introduction Ants are ubiquitous, widespread, and abundant in terrestrial ecosystems where they constitute a large fraction of the animal biomass (Fittkau and Klinge 1973). They occupy different trophic levels including predation, scavenging, granivory, and direct (i.e., leaf-cutting ants) and indirect (i.e., feeding on plant exudates and hemipteran honeydew) herbivory. They also play other important ecological roles as they mix and aerate the soil, recycle nutrients, disperse seeds, and have mutualistic associations with other arthropods and plants (Rico-Gray and Oliveira 2007; Lange et al. 2013). Ground-nesting ants likely constitute the first line of defense in the biotic protection of plants while foraging for prey on vegetation. Indeed, ant–plant interactions vary from facultative, “diffuse” relationships to obligatory, “specific” associations. In diffuse relationships, plants induce different ant species to patrol their foliage by producing energy-rich food rewards such as extrafloral nectar (EFN) and/or food bodies (FBs). However, in the myrmecophyte–ant associa- tion, strict and necessary to the survival of both partners, the plant offers a nesting place (in hollow structures called domatia) and frequently EFNs or FBs to specialized “plant-ants.” In return, the latter protect the myrmecophytes Communicated by: Sven Thatje A. Dejean : N. Labrière : A. Touchard : F. Petitclerc CNRS, Écologie des Forêts de Guyane (UMR-CNRS 8172), Campus Agronomique, BP 316, 97379 Kourou cedex, France A. Dejean (*) UPS, INP, Laboratoire Écologie Fonctionnelle et Environnement (Ecolab), Université de Toulouse, 118 route de Narbonne, 31062 Toulouse, France e-mail: alain.dejean@wanadoo.fr O. Roux IRD, MIVEGEC (IRD 224-CNRS 5290-UM1-UM2) Équipe BEES, 911 avenue Agropolis, BP 64501, 34394 Montpellier Cedex 5, France Naturwissenschaften DOI 10.1007/s00114-014-1159-1