Invasive ladybirds are really city slickers

Published: 10 October 2014 at 13:53

Anglia Ruskin scientist co-authors paper showing harlequins prefer urban areas

A new paper, co-authored by Anglia Ruskin University scientist Dr Peter Brown, shows that the invasive harlequin ladybird has a preference for Britain’s towns and cities.

By establishing rapidly in urban areas and overwintering inside buildings, the harlequin, first recorded in the UK in 2004, has severely affected native ladybird species which have suffered from the combined impacts of habitat deterioration and competition.

The new study, published today [13 October 2014] in the Journal of Biogeography, involved scientists from Anglia Ruskin University, the Centre for Ecology & Hydrology, the University of Edinburgh, and the University of Reading.

The research investigated the effect of both landscape and climactic factors on the spread of this ladybird.   It used records from citizen scientists who submitted around 23,000 sightings to the UK Ladybird Survey between 2003 and 2011.

While previous research on the same dataset had primarily focused on the effect of its broad diet and high reproduction rate, the new study compared sightings with spatial survival models in order to identify where the harlequin ladybird might appear next.

Spatial survival analysis has been widely applied in disease epidemiology but rarely used to explore the spread of invasive alien species.

Dr Peter Brown, Senior Lecturer in Zoology at Anglia Ruskin University, said:

“Urban environments can support large populations of ladybirds so are important habitats for these charismatic insects. 
“It is a serious concern that harlequin ladybirds appear to be displacing some native species in these habitats.  People can continue to help this research by contributing records to the UK Ladybird Survey.”

Lead author Dr Bethan Purse, from the Centre for Ecology & Hydrology, said:

“Our new study indicates that environmental factors, particularly habitat, have made some areas of Britain such as cities more vulnerable to rapid invasion of the harlequin ladybird than other areas, even after recording intensity and proximity to initial invasion sites are accounted for.”

The results also show that the harlequin ladybird has struggled to spread into coniferous woodland.  A number of ladybird species within Britain are largely confined to coniferous woodland and it appears that such habitats are more resistant to invasion by the harlequin.

The study was funded by the Natural Environment Research Council and the Joint Nature Conservation Committee.