What makes the invasive Harmonia axyridis so successful? Six years of research in Gembloux provide additional answers

Following the introduction of the invasive species Harmonia axyridis (Pallas) in Europe, many research works were conducted on its ecological, economic and social impacts. Recently, our team has been involved in the characterization of the behavioral traits making this lady beetle species so successful. The main conclusions of two PhD works will be shortly presented: (1) Through a six-year inventory performed in Belgian agroecosystems, we have demonstrated that H. axyridis has become well established and was among the most abundant aphidophagous predatory species, causing a severe depression of biodiversity, even if communities of aphid predators are still quite diversified. (2) The social issues associated with the establishment of overwintering aggregations in human constructions were also carefully investigated. We have demonstrated the importance of social interactions on the establishment and cohesion of the aggregates. Finally, we have demonstrated that the deposition of a set of saturated and non-saturated hydrocarbons on the surfaces where the lady beetles were settling on, allowed their conspecifics to follow their markings and join the group.