title: Role of long-chain hydrocarbons in the aggregation behaviour of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae).
abstract: The multicoloured Asian ladybirds, Harmonia axyridis (Pallas), form large aggregations inside dwellings to survive cold winters, causing annoyance to householders due to their abundance, allergenic properties and problems consequent on reflex bleeding. Flight to overwintering sites and macrosite choice of this species is well documented. H. axyridis shows a hypsotactic behaviour and a clear preference for contrasting visual elements. However, how the microsite is selected remains undocumented, although a better understanding of the factors implicated could lead to the development of new control methods for this pest. In this work, we hypothesised that non-volatile compounds are involved in the microsite choice and aggregation of this beetle. Long chain hydrocarbons were identified at aggregation sites, comprising saturated and unsaturated homologues. An aggregation bioassay was then conducted on overwintering individuals, highlighting the retention capacity of the identified compounds on the tested ladybirds. Additional investigations showed that H. axyridis males and females, originating from overwintering sites, deposit a similar blend of molecules while walking. A Y-shaped tube assay revealed that this blend is used by male and female congeners as cue allowing individuals to orientate towards the treated side of the olfactometer. These results suggest the use of two different blends of long chain hydrocarbons by H. axyridis during its aggregative period, the first one to lead conspecifics towards aggregation sites (microsites) and the second to ensure the cohesion of the aggregation. These findings support the potential use of these blends, in association with volatiles, in the design of traps in order to control infestations of this species in dwellings.
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Passage des Déportés 2, 5030 Gembloux, Belgium. D.Durieux@ulg.ac.be
authors.forename: Delphine
authors.initials: D
authors.lastname: Durieux
authors.forename: Christophe
authors.initials: C
authors.lastname: Fischer
authors.forename: Yves
authors.initials: Y
authors.lastname: Brostaux
authors.forename: John J
authors.initials: JJ
authors.lastname: Sloggett
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Deneubourg
authors.forename: Axel
authors.initials: A
authors.lastname: Vandereycken
authors.forename: Emilie
authors.initials: E
authors.lastname: Joie
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Wathelet
authors.forename: Georges
authors.initials: G
authors.lastname: Lognay
authors.forename: Eric
authors.initials: E
authors.lastname: Haubruge
authors.forename: François J
authors.initials: FJ
authors.lastname: Verheggen
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D002755:Choice Behavior / Q000502:physiology*; D001517:Coleoptera / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006838:Hydrocarbons / Q000032:analysis / Q000378:metabolism*; D008297:Male
chemical_list: D006838:Hydrocarbons