Reference : Production of alarm pheromone in aphids and perception by ants and natural enemies
Dissertations and theses : Doctoral thesis
Life sciences : Entomology & pest control
Production of alarm pheromone in aphids and perception by ants and natural enemies
[fr] Production de phéromone d'alarme chez les pucerons et perception par les fourmis et les enemies naturels
Verheggen, François mailto [Université de Liège - ULg > > Gembloux Agro-Bio Tech >]
Université de Liège, ​​Belgium
Doctorat en sciences agronomiques et ingéniérie biologique
Haubruge, Eric mailto
Thewis, André mailto
Francis, Frédéric mailto
Lognay, Georges mailto
Detrain, Claire
Hance, Thierry
[en] Aphids ; Alarm pheromone ; Chemical Ecology
[en] Most Aphidinae species produce and use (E)-ß-farnesene (Eßf) as an alarm pheromone. This
sesquiterpene is released by individuals under attack by a predator, and nearby aphids exhibit a variety of alarm behaviours. This PhD thesis aims to better understand how aphids manage their production and emission of alarm pheromone (Chapter IV). We also wanted, in a second step, to improve our knowledge on the roles that Eßf could play in the relationships that aphids have with their predators (Chapter V) and tending ants (Chapter VI), in order to better pinpoint the problem in this very tough context. The aphid predators have indeed a real advantage to be able to use the odorant cues emitted by their prey, to locate them and to select an adequate oviposition site. Ants establish with certain aphid species mutualistic relationships, which occurrence could be facilitated by the use of aphids’ odours. In Chapter IV, we have highlighted that aphid colonies non subjected to attack by predators release constantly small quantities of Eßf in their headspace, which means that this molecule could have additional roles than just acting as an alarm pheromone. In a second study, we demonstrated that the release of Eßf was not contagious, and therefore that a non stressed aphid receiving the alarm signal does not release additional Eßf. Since the production of alarm pheromone is likely to entail physiological cost, we tested and validated the hypothesis that aphids regulate their Eßf production according to their social environment. In Chapter V, we studied the ability of the hoverfly predator Episyrphus balteatus (Diptera, Syrphidae) to be used as biological control agent against aphids infesting tomato plants (Lycopersicon esculentum). After identifying the odours emitted by aphid infested plants, we have demonstrated that although this Diptera is able to perceive all the odours released by the system, it mainly uses Eßf to select its oviposition site. However, the E. balteatus larvae are not adapted to the architecture of tomato plants. We also showed that the Asian ladybeetle Harmonia axyridis (Coleoptera, Coccinellidae) olfaction was adapted to the perception of Eßf and that this beetle is also attracted by this sesquiterpene. Finally, in Chapter VI, we characterized the benefits accruing to aphid populations that have established mutualistic relationships with Lasius niger (Hymenoptera, Formicidae), and have demonstrated the role of Eßf and honeydew, respectively in locating aphid colonies and in the persistence of the mutualism.

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