Sunday, May 20, 2012

The leaf beetle family

Chrysolina variolosa
Leaf beetles are members of an insect family represented  by about sixty species in Malta

The one pictured with this article is known simply as a leaf beetle and in Maltese as żabbella a name that was used also for the ladybirds. The scientific name which distinguishes this beetle from all other leaf beetles is Chrysolina variolosa.

This species is frequent although not common. 

It is usually found on the spiny asparagus, (spraġġ in Maltese) as it probably eats its leaves.

But the specimen I photographed last Sunday at Mistra Bay was walking on rocks far from any asparagus plant.

The leaf beetle family is the largest and most commonly encountered beetle family. It is estimated that there are over 35,000 species in this family. Several species are of economic importance because of their impact on agricultural produce. 

Some have been used to control weeds biologically especially in Australia and in California.

But the greatest impact is probably that of another species - the Colorado potato beetle which can devastate entire crops of potato.

The Colorado potato beetle is indigenous to the Americas but it was not until 1840 that it started to become a pest of the potato plant. 

It appeared in Germany in Germany in 1877 but was soon eradicated from there. It reappeared in Europe sometime during World War I. It was first observed near American military bases in Bordeaux and from there it spread to Belgium, the Netherlands and Spain eating its way through potato fields.

Soon after the Colorado potato beetle started to spread in Europe the Maltese Government, prohibited the importation of crops from any areas where this beetle was present and managed to keep the Maltese islands free from this pest.

In 2008 the European Union issued a Directive by means of which Malta was declared a protected zone and was thus given special protection to be able to take measures such as plant quarantine to keep the Colorado potato beetle away from the islands. 

This article was published in The Times on 23.11.11)

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