title: An invasive ant species able to counterattack marabunta raids.
abstract: In the Neotropics where it was introduced, the invasive ant Pheidole megacephala counterattacked raids by the army ants Eciton burchellii or E. hamatum. The Eciton workers that returned to their bivouac were attacked and spread-eagled and most of them killed by their outgoing colony mates. Little by little the zone where returning and outgoing Eciton workers encountered one another moved away from the Pheidole nest which was no longer attacked, so that most of the colony was spared. Using a water-based technique rounded out by bioassays, we show that Pheidole compounds were transferred onto the Eciton cuticle during the counterattacks, so that outgoing workers do not recognize returning colony mates, likely perceived as potential prey. Because P. megacephala is an introduced African species, this kind of protection, which cannot be the result of coevolutive processes, corresponds to a kind of by-product due to its aggressiveness during colony defence.
authors.affiliation: CNRS UMR 8172, Écologie des forêts de Guyane, BP 316, 97379 Kourou cedex, France; Université de Toulouse, UPS, INP, laboratoire Écologie fonctionnelle et Environnement (Ecolab), 118, route de Narbonne, 31062 Toulouse, France. Electronic address: alain.dejean@wanadoo.fr.
authors.forename: Alain
authors.initials: A
authors.lastname: Dejean
authors.affiliation: Université de Toulouse, UPS, INP, laboratoire Écologie fonctionnelle et Environnement (Ecolab), 118, route de Narbonne, 31062 Toulouse, France; CNRS UMR 5245, Ecolab, 31062 Toulouse, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Azémar
authors.affiliation: IRD; MIVEGEC (IRD 224 CNRS 5290-UM1-UM2) Équipe BEES, 911, avenue Agropolis, BP 64501, 34394 Montpellier cedex 5, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Roux
mesh_terms: D000374:Aggression / Q000502:physiology*; D000818:Animals; D001000:Ants / Q000502:physiology*; D008401:Gas Chromatography-Mass Spectrometry; D006838:Hydrocarbons / Q000737:chemistry; D011235:Predatory Behavior / Q000502:physiology*; D021641:Recognition, Psychology; D013045:Species Specificity
chemical_list: D006838:Hydrocarbons
keywords: Antipredation; Antiprédation; Army ants; Colony mate recognition; Eciton; Fourmis légionnaires; Pheidole; Reconnaissance coloniale