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Harlequin ladybirds are taking over the world

Vegetable and flower growers appreciate the work ladybirds do in keeping away aphids and other pests, but in ecology, balance is key.

By Brooks Hays
The harlequin ladybird was introduced in the United States in the early 20th century to keep aphids off crops. Photo by Maris Midgley
The harlequin ladybird was introduced in the United States in the early 20th century to keep aphids off crops. Photo by Maris Midgley

LONDON, March 31 (UPI) -- Most farmers and gardeners welcome the arrival of ladybirds -- or ladybugs, as they're known in the United States. But the beetles are actually invasive, and one species, the harlequin ladybird, is taking over fast.

"The rapid spread of this species has inspired biologists to study the process of invasion on a global scale," Helen Roy, a researcher at the the Centre for Ecology and Hydrology in England, said in a news release.

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Originally from Asia, the spotted beetle is now found throughout the United States, in parts of Canada, and most of Europe. The harlequin ladybird, Harmonia axyridis, has also made its way to a few regions of South America, as well as parts of northern and southern Africa.

It took just four years after its initial introduction for the species to spread across all of the Netherlands. The beetles was first found in western Russia in 2010. Every year since, its range has spread nearly 200 miles to the south.

Vegetable and flower growers appreciate the work ladybirds do in keeping away aphids and other pests, but in ecology, balance is key.

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Scientists are now working to identify natural enemies of the ladybird that might be able to keep the beetle in check. One helpful species is the parasitic wasp Dinocampus coccinellae, which is found all over the world and uses all types of ladybird species as hosts.

Though researchers are now closely monitoring the ladybug's rapidly expanding range -- with the help of citizen scientists -- they still aren't sure what effects the beetle's growing presence is having on the ecosystem.

To find out, they'll need to keep monitoring the harlequin ladybird.

The latest research was published in the journal Insect Invasions.

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