Tuesday, 7 August 2012

Harlequin ladybirds becoming a major pest

Introduction of Asian ladybirds into Europe serious mistake
August 2012. In retrospect, introducing the Asian (Harlequin) ladybird into Europe was a serious mistake. The insect was introduced some twenty years ago in a conscious attempt to combat aphids. But research carried out at Wageningen UR (University & Research centre) into the invasion of this foreign insect has shown that the disadvantages far outweigh this single advantage. The Asian species is displacing the native European ladybird and has become a pest that can contaminate homes and spoil the taste of wine.
The Asian ladybird, Harmonia axyridis, which originated in China and Japan, is larger than its European counterpart and has an almost invisible dent towards the rear of its wing cover; but the colour and dots are much the same which can make identification difficult.
Introduced into France & Netherlands
The foreign insect was introduced into France in the early 90s, and was first used in the Netherlands in around 1996. The Asian ladybird was thought to be a formidable weapon in the fight against aphids in greenhouses and on avenue trees, from which lice excrete sticky honeydew onto cars.
Eating native ladybirds
However, time has shown that these insects, which have very few natural enemies in Europe, are also devouring the native ladybirds. Furthermore, colonies of the Asian variety hibernate in houses and other buildings, where their excrement can cause contamination. 

Attacking vinyards
Last but least, it has been discovered that when the supply of aphids runs out, this insect has an appetite for grapes and spoils the taste of the wine.

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