Saturday, 23 August 2008

First Harlequin Ladybird

At Claines Canna, we have seen our first Harlequin Ladybird today. It was in the vegetable patch on a crop of purple sprouting broccoli. The bed had been invaded by white fly and it had a good food supply to get on with!

Maybe, a good aphid controller like the Harlequin could be a blessing to Canna growers in the UK. Our biggest problem, besides the weather, is Canna virus. The vector for transmission of the disease is aphids. Our native ladybirds make a whole-hearted effort at consuming aphids, but they, themselves, are subject to two threats - 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 the Harlequin Ladybird is totally resistant to natural enemies here."

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.

"Gardeners need to take a pragmatic view and accept the fact that the harlequin ladybird is here to stay. Its food of choice is greenfly and other aphids, so it is going to help gardeners to control these troublesome pests."

So, there we have it. The Harlequin has arrived in Worcester and it's not going away. Let's look on the positive side and hope that, whatever other ecological damage it does, it controls the aphid population that has been over-whelming us for the last 20 years.

Maybe, I might start growing roses again!

No comments:

Post a Comment