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Harmful fruit fly on its way to Belgium

Drosophila suzukii or ‘spotted-wing drosophila’, is the name of the latest addition to the Belgian list of flies. But whether this variety is really welcome is an open question. This fruit fly is an invasive kind of pest which in America already causes heavy losses in the fruit sector.
 
On 21 November 2011 in a garden in Oostende a small but typical fruit fly was collected. The fly, about 2.5 mm in size, was after some research identified as the Drosophila suzukii. The long hairy feelers on the antennae, the big spots on the wing top, the double rows of brushes across the legs and the coloured behind showed this one to be a male. An exceptional find, never before established in Belgium. In addition this kind is known as an exceptionally invasive kind of pest.
 
The first determined member of Drosophila suzukii in Belgium
Contrary to most fruit flies, which lay their eggs in rotten fruit, this variety does this in ripening fruit. The eggs grow into larvae, which destroy the fruit. The pulp becomes soft and impossible to eat. In general fruit growing in gardens, such as cherries, raspberries, bilberries, grapes and strawberries are favourite places to lay the eggs. In principle every fruit with a thin skin, both cultivated and wild, is a potential site to lay eggs. As soon as the female lays her eggs underneath the skin of the fruit very often contamination by bacteria and mildew come into play causing the fruit to deteriorate even quicker.
 
In 2009 the variety was spotted for the first time in Europe: first in Italy, shortly after in France. The next year Spain, Slovenia and Switzerland followed. Where the variety was only apparent more southerly now is much more northerly at the Belgian coast, In the area of origin - China, Japan and some surrounding countries - this Drosophila variety is active through the entire year. This latest Belgian observation makes one think that the fly can do this in Europe as well. She has an exceptionally fast life cycle, which is often completed within ten days. The distribution within an area is very quick as a result, both by full grown flies and the larvae which are moved with the rotten fruit. It is suspected that this newcomer, as soon as more moderate areas such as Northern Europe are reached, could acquire a more invasive character. Because of the great potential to grow into a real pest EPPO (European and Mediterranean Plant Protection Organisation) decided to keep track of its arrival in Europe.
 
In America they already have rotting pears. In 2008 the first variety showed itself
and mainly on the west coast. Drosophila suzukii did a lot of damage. Recently it also appeared at the east coast. As a result certain orchards had crops which were up to 25% smaller than average. In a nursery in Oregon just about the entire crop was destroyed! Such enormous losses were not as yet reported in Europe. The variety, however, extends its area in Europe and therefore good counter measures
are necessary.
 
Is this observation the beginning of a new kind of pest? For the time being we are O.K. Research in America made it clear that potential invasions can de controlled quite cheaply by putting simple bottle traps in the orchards. There are therefore solutions, but it remains important to keep a strict watch on this variety!
 
 
 

Publication date: 12/2/2011


 


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