title: Foraging leaf-cutting ants learn to reject Vitis vinifera ssp. vinifera plants that emit herbivore-induced volatiles.
abstract: Leaf-cutting ants (LCAs) are dominant herbivores of the Neotropics, as well as economically important pests. Their foraging ecology and patterns/mechanisms of food selection have received considerable attention. Recently, it has been documented that LCAs exhibit a delayed rejection of previously accepted food plants following treatment with a fungicide that makes the plants unsuitable as substrate for their symbiotic fungus. Here, we investigated whether LCAs similarly reject plants with induced chemical defenses, by combining analysis of volatile emissions with dual-choice bioassays that used LCA subcolonies (Atta sexdens L.). On seven consecutive days, foraging ants were given the choice between leaf disks from untreated control plants and test plants of Vitis vinifera ssp. vinifera L. treated with the phytohormone jasmonic acid (JA) to mimic herbivore attack. Chemical analysis revealed the emission of a characteristic set of herbivore-induced volatile organic compounds (VOC) from JA-induced plants. Dual-choice experiments indicated that workers did not show any preference initially, but that they avoided JA-treated plants from day five onwards. Our finding that A. sexdens foragers learn to avoid VOC-emitting plants, which are likely detrimental to their symbiotic fungus, represents the first evidence for avoidance learning in attine ants toward plants with induced defenses.
authors.affiliation: Plant Ecology and Systematics, University of Kaiserslautern, P.O. Box 3049, 67653, Kaiserslautern, Germany.
authors.forename: Theresa
authors.initials: T
authors.lastname: Thiele
authors.forename: Christian
authors.initials: C
authors.lastname: Kost
authors.forename: Flavio
authors.initials: F
authors.lastname: Roces
authors.forename: Rainer
authors.initials: R
authors.lastname: Wirth
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D003517:Cyclopentanes / Q000494:pharmacology; D005247:Feeding Behavior; D060434:Herbivory; D054883:Oxylipins / Q000494:pharmacology; D018515:Plant Leaves; D027843:Vitis / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D055549:Volatile Organic Compounds
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D055549:Volatile Organic Compounds; C011006:jasmonic acid