It's becoming harder to spot native ladybird with invader species
Published 15/06/2011 | 05:00
A newly published atlas which maps all 47 different ladybirds in Ireland and Britain reveals that, in the UK, 10 species of the speckled insect have been decreasing in the past 20 years.
The dramatic decline across the Irish Sea is linked to the arrival there in 2004 of the invasive Asian Harlequin ladybird which competes for food and preys on the larvae of other smaller species.
And the bad news for Irish ladybirds is that the same invasive species was found in Cork and Wicklow last year.
The sighting of two Harlequin ladybirds here prompted John Kelly from Invasive Species Ireland to issue an appeal to the public to report any suspected cases of the species.
Now the publication of the atlas confirms the devastation the Asian arrival has wreaked on ladybird populations in the UK and environmentalists fear it is only a matter of time before the problem is recreated here.
Dr Helen Roy, from the Centre for Ecology and Hydrology (CEH) and one of the authors of the atlas, the result of a six-year research project, said: "What's quite striking is that in the same way as butterflies and moths have seen very common species going into decline, we're seeing the same happen with ladybirds."
But while butterflies feed on nectar from wildflowers, "ladybirds are predatory and carnivorous species" on the next level up the food chain, she said.
"They are telling us there are changes going up through the food chain. Ladybirds can be used as indicators of wider changes in our environment."
Tony Lowe of Friends of the Irish Environment said the "worrying" decline in bees and other insects was caused by the disappearance of wilderness from the habitat.
"We are squeezing out so much biodiversity and when there is an invasive species, it makes the situation worse," he said.
The new atlas is based on records originally gathered by experts but has received widespread contributions from the public.