Asian Harlequin Ladybird Now Dominant Species
The Asian harlequin ladybird has become the dominant species in the
south east of England in less than four years, scientists have said.
A nationwide survey shows that the insect, which originated in Japan,
has gone from a handful of sightings in 2004 to virtually total
coverage of the South East and is now found as far afield as Scotland,
Northern Ireland and Wales.
With its voracious appetite and longer breeding period there are fears
it could threaten the survival of the 46 domestic ladybird species.
The findings of the UK Harlequin Ladybird Survey were underlined by
separate research which named the harlequin as Britain's second
biggest garden pest of last year.
It is described as "the most invasive ladybird on Earth" by scientists
from the Centre for Ecology and Hydrology, Cambridge University and
Anglia Ruskin University, who compiled the survey.
They found that its rapid spread is largely down to its resistance to
the two main enemies of native ladybirds - a parasitic wasp and a fungus.
Dr Helen Roy of the Centre for Ecology and Hydrology said: "It is
fascinating, if a little bleak, that it is totally resistant to
natural enemies here."
Dr Roy said that the ladybird was being found in lime trees and
sycamores where it ate aphids and other aphid predators, such as
lacewings and horse fly larvae.
It also ate native ladybirds and cannibalised its own species.
"Staggering scenes of carnage are going on," she said.
A study in Oxford showed that the harlequin ladybird was now the
dominant ladybird species found in trees. This was leading to a
reduction in the number of native species, she said.
The harlequin, which was introduced into Europe as a form of
biological control aimed at aphids, already rivals other model
examples of invasive species without native enemies such as the grey
squirrel, added Dr Roy.
The growing dominance of the harlequin was also illustrated by its
first appearance in the Royal Horticultural Society's list of the ten
biggest garden pests of 2007. Only slugs and snails presented a bigger
problem for gardeners.
Andrew Halstead, principal entomologist for the RHS, said: "The
harlequin ladybird rapidly established itself in England and there is
no possibility of eradicating it or preventing its further spread.
Telegraph: March 2008
