Giant mutant ant colony found in Australia

MELBOURNE, Australia (AFP) - A huge ant colony measuring 100 kilometres (62 miles) across has been found under the southern Australian city of Melbourne, scientists said.

Monash University researcher Elissa Suhr said the supercolony of Argentine ants was threatening native biodiversity in Australia's second largest city.

Suhr said the introduced pest's natural aggression kept numbers under control in its native country but the genetic make-up of the ants found in Australia had mutated allowing them to cooperate to build the supercolony.

"In Argentina, their native homeland, ant colonies span tens of metres, are genetically diverse and highly aggressive towards one another," Suhr said.

"So population numbers never explode and they are no threat to other plants and animals.

"When they arrived in Australia, a change in their structure occurred, changing their behaviour so that they are not aggressive towards one another. This has resulted in the colonies becoming one supercolony."

Suhr said the Argentine ants killed native ants and the insect life they normally preyed upon, posing a major threat to biodiversity.

She said Argentine ants were ranked among the world's 100 worst animal invaders and had found an ideal habitat in the Mediterranean-type eco-systems of south-eastern Australia.