Harlequin ladybird invasion could endanger 1000 native UK species 30/06/2009 11:50:34

Harlequin succinea - Credit the late Professor Mike Majerus of Cambridge University.

June 2009. Scientists presenting at the Royal Society Summer Science Exhibition, which opened on 30th June will say that the harlequin ladybird is likely to threaten over 1000 native species in Britain.

Spread across the country in just 4 years
The harlequin has spread from Essex to Orkney in only four years and is now one of the fastest spreading non-native insects in Europe and the most invasive ladybird on Earth. Scientists from across the UK have been working to monitor its spread and impact. They are also seeking inventive methods of control, some of which will be presented at the Exhibition.

Harlequin caused severe declines in the USA
Project leader, Dr Helen Roy from the Centre for Ecology & Hydrology said: "We believe that the negative impacts of the harlequin on Britain will be far reaching and disruptive, with the potential to affect over 1000 of our native species. In the United States, where the harlequin arrived over 20 years ago, it has been associated with severe declines in native species."

The researchers' first step has been to understand how the harlequin has spread. The public has played a key role in monitoring the invasion through the Harlequin Ladybird Survey (www.harlequin-survey.org), which was launched in 2005, and has now received over 30,000 online records.

Invasive alien species - Major threat to biodiversity
"Invasive alien species are one of the greatest threats to global biodiversity," says co-investigator Dr Remy Ware from the University of Cambridge. "Using data from the Harlequin and UK Ladybird Surveys, we have a unique opportunity to study the early establishment, spread and adaptation of an invasive species."

Natural, native enemies
The research team are now exploring how the few native enemies that do exist could be used to control the harlequin invasion. One of the most promising ideas is using a sexually transmitted mite, which makes some ladybirds infertile. If the transmission of these mites could be encouraged, the harlequin population could become greatly reduced. Other possible control options are through fungal disease, male-killing bacteria, a parasitic wasp and two species of parasitic fly.

The scientists will be on hand at the exhibition, which runs from 30 June to 4 July, to talk visitors through their research. On the exhibition stand, visitors can learn how to distinguish harlequins from native species, get up close and personal with harlequins under the microscope, and find out how scientists are trying to control the invasion.

• Britain has 45 different species of native ladybird, which play a key role in the ecosystem.
• Many ladybirds are voracious predators of crop and garden pest insects, particularly aphids.
• The harlequin can eat over 12,000 aphids in a year. Unfortunately, harlequins prey on more than just pest insects, and will eat non-pest and beneficial insects, including the larvae of other ladybirds.
• Since the 1990s, a scientist at the University of Cambridge, the late Professor Mike Majerus, had widely expressed his concerns that the harlequin ladybird would soon arrive in Britain and have devastating effects.
• The harlequin, native to Asia, was introduced to North America and continental Europe as a biological control agent as it eats more pest insects than any other ladybird. In 2004, it arrived in Britain and is now thought to be threatening 1000 native species, confirming Mike's worst fears.
  

• Ladybirds don't have many enemies. They are distasteful or toxic to many predators and advertise this with their bright colouring. A yellow fluid is released when they are disturbed, which is packed full of bitter-tasting chemicals.
• Adult harlequins can be a nuisance, entering our homes in autumn in their thousands to sleep out the winter on window frames, curtains and in attics. As their prey becomes scarce in autumn, they may feed on fruit, such as grapes, causing damage in vineyards and contaminating wine.
• The harlequin can also have negative impacts on native biodiversity. In the United States, where the harlequin arrived over 20 years ago, it has been associated with severe declines of many native species and, through the Survey, we are already getting indications of native species at risk in Britain.
  

Harlequin ladybirds, Hertford in 2007 - Photo credit Shirley Taylor.