An invasive ladybird in rural habitats: Harmonia Axyridis (Coleoptera: Coccinellidae) in the UK

This study investigates how the invasive alien harlequin ladybird Harmonia axyridis affects the ladybird (Coleoptera: Coccinellidae) community in rural habitats in the UK. A novel approach to species distribution models was used to determine where H. axyridis may next spread under various climate change scenarios. Field surveys were carried out in England and Wales to investigate how H. axyridis affects native coccinellids in rural habitats, including the rare 5-spot ladybird Coccinella quinquepunctata. Molecular techniques were employed to determine if intraguild predation occurred between H. axyridis and C. quinquepunctata. A combination of variables had an impact on the establishment and spread of H. axyridis with human influence being the most important factor. The future spread of H. axyridis is predicted to be affected by climate change, with a shift in global distribution expected north and west. In the UK, this species is predicted to spread further into areas such as Scotland and mid-Wales. Unlike urban habitats, rural woodlands are not dominated by H. axyridis. Furthermore, a distinct community of coccinellids is evident in both coniferous and deciduous woodland. Coccinella quinquepunctata appears not be negatively affected by H. axyridis at this time. It is thought this is due to the inhospitable habitat that C. quinquepunctata occupies. However, using molecular techniques, it was not possible to confirm if intraguild predation had occurred at the sites where C. quinquepunctata and H. axyridis were both observed. A range of interacting factors are necessary for H. axyridis to establish in a region and once established this species will spread to rural habitats yet does not dominate the coccinellid community as it does in urban habitats. Continued monitoring thorough Citizen Science is essential in further understanding this dynamic species and its impacts on native coccinellids.