Cannibal harlequin ladybirds from East Asia have been feasting on native ladybird species across Europe, scientists have discovered.
The harlequin ladybird was first spotted in the UK in 2004 and is much larger that native British species. It is one of the fastest spreading invasive insects in the world.
Scientists at Anglia Ruskin University have examined the harlequin ladybird DNA to discover that the species is cannibalistic, eating other ladybird species across Europe.
Lead authors Peter Brown and Alison Thomas found DNA of several native insect species in the guts of harlequin ladybirds.
They examined 177 larvae from the wild in England, France, Germany, Slovakia and Czech Republic. Other species the harlequin ladybird ate included hoverflies and lacewings.
Published in the journal Entomological Science, the authors note that the harlequin ladybird is believed to be responsible for the decline of several native ladybird species because of direct predation and competition.
Brown warned that an increase in the harlequin species will further threaten those native to Britain and the rest of Europe: "This study shows that harlequin ladybirds in the wild commonly prey on a number of insects, other than just aphids. The results offer further evidence that the harlequin is a generalist predator which is having a damaging effect on native species across Europe.
"Ladybirds and other aphid-feeding insects are a very important part of ecosystems, acting as natural pest controllers. There are 47 ladybird species in the UK and it is vital that this diversity is maintained."