title: Aggregation behavior of Harmonia axyridis under non-wintering conditions.
abstract: The invasive multicolored Asian ladybeetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), aggregates inside dwellings during winter to avoid cold weather. This adaptive behavior disturbs homeowners, because of the large numbers of individuals that aggregate, which induces allergic reactions. The migratory flight patterns of this species have been well documented, with individuals preferentially moving toward prominent and high color contrast elements. However, the factors involved in the selection of aggregation sites by this species have yet to be elucidated. Here, we evaluated the influence of (i) the density of individuals and (ii) the type of available shelters on decisions by H. axyridis to settle and aggregate under shelters. A dual choice bioassay conducted in the laboratory demonstrated the presence of mutual attraction to conspecifics. We also found that individuals preferentially settled under red covered shelters compared to transparent shelters, and that the type of shelter outweighed the effect of social interactions among conspecifics. Moreover, this experiment was performed under non-wintering conditions, providing the first evidence that aggregative behavior in this species can also occur under those specific conditions.
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: Delphine
authors.initials: D
authors.lastname: Durieux
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: Bérénice
authors.initials: B
authors.lastname: Fassotte
authors.affiliation: Unit of Social Ecology, Université libre de Bruxelles, Brussels, Belgium.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Deneubourg
authors.affiliation: Applied Statistics, Computer Science and Mathematics, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: Yves
authors.initials: Y
authors.lastname: Brostaux
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: Axel
authors.initials: A
authors.lastname: Vandereycken
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: Emilie
authors.initials: E
authors.lastname: Joie
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: Eric
authors.initials: E
authors.lastname: Haubruge
authors.affiliation: Functional and Evolutionary Entomology, Gembloux Agro-Bio Tech, University of Liege, Gembloux, Belgium.
authors.forename: François J
authors.initials: FJ
authors.lastname: Verheggen
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D002755:Choice Behavior; D001517:Coleoptera / Q000502:physiology*; D003116:Color; D058865:Introduced Species; D012621:Seasons; D012919:Social Behavior
keywords: group effect; invasive species; luminosity; multicolored Asian ladybeetle; shelter selection; social behavior