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Harlequin Ladybird Putting 1,000 UK Species At Risk

June 30, 2009

Scientists have warned that the Harlequin ladybird is putting over 1,000 species in the UK in peril, BBC News reported.

Dr. Helen Roy of the Center for Ecology and Hydrology called the rate of spread “dramatic and unprecedented.”

In just four years, the ladybird has spread to most parts of the UK, where it feeds on many other insects.

But the Royal Society’s Summer Science Exhibition produced research that suggests local ladybird parasites are adapting to prey on the interloper.

Scientists are now suggesting introducing a mite that renders the ladybirds infertile in an effort to help that process along.

The harlequin, which originally came from Asia, preys on a wide variety of insects, including the larvae of other ladybirds, and it will also eat fruit. It was introduced in continental Europe to control pest insects.

The tiny invader insect was quickly classified as a major threat to the UK’s 45 native ladybird species when it was first “spotted” in 2004 around Essex.

Experts have been tracking its spread since 2005 with a survey that invites members of the public to report sightings.

Roy said the southeast is the stronghold, but they have also reached Orkney, Northern Ireland, far west Wales and far west Cornwall.

He told BBC News the Harlequin ladybird is a top predator and experts are aware that it sits within a web of many other insects and organisms that it interacts with.

Roy said they believe that 1,000 species all have the potential to be impacted because there’s nothing very much that attacks it.

Several potential measures to stop the frantic spread of the ladybirds are being looked into by Dr. Remy Ware of Cambridge University.

She said that parasitoids, which are natural enemies of UK ladybirds, are adapting to prey also on the Harlequin. Parasitoid flies and wasps lay their eggs inside ladybirds, killing them.

Ware told BBC News they have evidence from the past two years that these two groups may be adapting to attack the harlequin as a novel host.

A sexually transmitted mite that renders female ladybirds infertile may prove a more promising predator for the insects. The mite must be passed from one generation to the next by inter-generational mating.

However, there is not enough time for the mite to propagate, given that native ladybird species produce just one generation per year. But the Harlequin has as many as five generations per year, making it an ideal candidate to carry and pass on the mite.

But Ware said they’re not suggesting that they introduce a novel enemy into the UK.

“It’s actually already here and in time we expect it would naturally take on in the harlequin,” she explained.

While she stresses that the suggestions are still in the formative stages, Ware said they’ve developed methods whereby they can artificially infect Harlequin ladybirds with the mite.

“It’d be a case of infecting them and releasing into the wild,” she said.

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