title: Do aphid colonies amplify their emission of alarm pheromone?
abstract: When aphids are attacked by natural enemies, they emit alarm pheromone to alert conspecifics. For most aphids tested, (E)-beta-farnesene (EBF) is the main, or only, constituent of the alarm pheromone. In response to alarm pheromone, alerted aphids drop off the plant, walk away, or attempt to elude predators. However, under natural conditions, EBF concentration might be low due to the low amounts emitted, to rapid air movement, or to oxidative degradation. To ensure that conspecifics are warned, aphids might conceivably amplify the alarm signal by emitting EBF in response to EBF emitted by other aphids. To examine whether such amplification occurs, we synthesized deuterated EBF (DEBF), which allowed us to differentiate between applied and aphid-derived chemical. Colonies of Acyrthosiphon pisum were treated with DEBF, and headspace volatiles were collected and analyzed for evidence of aphid-derived EBF. No aphid-derived EBF was detected, suggesting that amplification of the alarm signal does not occur. We discuss the disadvantages of alarm signal reinforcement.
authors.affiliation: Institute of Ecology, Friedrich-Schiller University, Dornburger strasse 159, Jena, Germany.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Hatano
authors.forename: Grit
authors.initials: G
authors.lastname: Kunert
authors.forename: Stefan
authors.initials: S
authors.lastname: Bartram
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Boland
authors.forename: Jonathan
authors.initials: J
authors.lastname: Gershenzon
authors.forename: Wolfgang W
authors.initials: WW
authors.lastname: Weisser
mesh_terms: D000818:Animals; D001042:Aphids / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects*; D008401:Gas Chromatography-Mass Spectrometry; D010675:Pheromones / Q000378:metabolism* / Q000494:pharmacology; D012717:Sesquiterpenes / Q000494:pharmacology*; D014835:Volatilization
chemical_list: D010675:Pheromones; D012717:Sesquiterpenes; C062671:beta-farnesene