Researchers from the Centre for Ecology and Hydrology in the UK and the Institute for Nature and Forest (INBO) in Belgium have discovered a species of alien ladybirds that have invaded in Europe.
Apparently the non-native Harlequin ladybirds are replacing the 2-spot native ladybirds, leading to the large spatial-scale decline of the latter species. According to the researchers, after the arrival of the Harlequin, numbers of the 2-spot native ladybird had declined by 30 percent in Belgium and 44 percent in Britain over the five year period of the research.
The scientists examined thousands of ladybird distribution records, collected through public participation surveys in Britain and Belgium. They found that of the eight different species found in both Belgium and Britain, the numbers of five in the former and seven in the latter country had declined after the arrival of the Harlequin ladybird.
Fortunately, one species - the large 7-spot ladybird - has retained a stable distribution and can be found in abundant numbers across Europe.
"This study provides strong evidence of a link between the arrival of the Harlequin ladybird and declines in other species of ladybird, a result that would not have been possible without the participation of so many members of the public gathering ladybird records across Britain, Belgium and Switzerland," said Dr. Helen Roy from the Centre for Ecology and Hydrology.
"At the continental scale the arrival of the Harlequin could impact on the resilience of ecosystems and severely diminish the vital services that ladybirds deliver," said Tim Adriaens from the Research Institute for Nature and Forest.