Encounters with an alien: Harmonia axyridis in Europe

Abstract

Invasive species are considered among the greatest threats to global biodiversity. The rapid increase in introduced exotic species worldwide and the potential of these species to become invasive has ecological and evolutionary consequences. Ladybirds have a long history of use as biological control agents against pest insects. Indeed, the Australian vedalia ladybird, Rodolia cardinalis, is heralded as marking the advent of modern biological control. Harmonia axyridis was released in many European countries through the 1980 and 1990s and just a decade later there were many reports of establishment. Harmonia axyridis is now widely regarded as an Invasive Alien Species (IAS) first and foremost because it threatens the diversity of native aphidophagous species and may contribute to biotic homogenization. There are many lessons to be learnt from H. axyridis as a model IAS to help prevent, or mitigate, subsequent releases of high risk organisms. I will review the status of H. axyridis in Europe, from introduction to establishment, and consider where our encounters with this alien are contributing to understanding of biological invasions