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UN warns on threat of invasive species

MANY governments are ignoring alien invasive species such as weeds or rats that may be causing US$1.4 trillion damage a year to the world economy, the head of the United Nations Environment Program said yesterday.

"Time to get tough on alien species," UNEP head Achim Steiner wrote of insects, fungi, algae and other plants or animals often taken unwittingly by humans to new habitats, for instance in grain exports or in ships' ballast water.

Alien species may be "one of the least known threats to biodiversity and economies," he wrote in a statement to mark yesterday's International Biological Diversity Day.

"Far too many countries have failed to grasp the threat or are far too casual in their response," he said, praising countries including South Africa for eradication program or New Zealand for imposing tough customs controls.

He noted that one study put the cost of alien invasive species at US$1.4 trillion a year - almost 5 percent of the world economy - split between losses from introduced pests in crops, pastures and forests and other environmental damage.

"The US$1.4 trillion ... is still credible today," David Pimentel, a professor at Cornell University in the United States who led a 2001 study that came up with the number, said when asked if he might now revise the figure.

He said weeds and rats were the most destructive alien species that can thrive in new habitats when freed of natural predators.

Steiner pointed to the water hyacinth, a native of the Amazon basin with large flowers that has exploded in numbers since it was brought to Africa as an ornamental plant.

In Uganda, the hyacinths cause annual costs of US$112 million, by forming a floating mat choking parts of Lake Victoria since 1990. .

DAISIE, a project to curb invasive species in Europe, reckons there are more than 11,000 invaders of which 15 percent cause economic damage.


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