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Yellow crazy ants invade Australia
By Stephen Sheldon
UPI Science News
From the Science & Technology Desk
Published 3/4/2003 9:52 AM
SYDNEY, Australia, March 4 (UPI) -- Northern Australia has been invaded by one of the world's most destructive ant species, the yellow crazy ant, which scientists said has the potential to destroy wildlife and agriculture across the top half of the continent.
"This is an invasive alien species which has catastrophic effects wherever it goes," Dennis O'Dowd, an ecologist and crazy ant specialist at Melbourne's Monash University, told United Press International. "It is recognized by the Global Invasive Species Database as one of the world's 100 worst invaders, and is a major threat to biodiversity."
Ben Hoffmann, an ant specialist with the Commonwealth Scientific and Industrial Research Organization, is leading the fight to eradicate the ant from northern Australia's Arnhem land. He told UPI that researchers have found 63 nests on the eastern tip of the Gove Peninsula, near a former U.S. military base from World War II. He said the proximity of the nests to the former base has led to conjecture that crazy ants entered Australia long ago via American troop ships from Indonesia.
One of the crazy ant's nightmarish characteristics, Hoffmann said, is because the queens do not fly, the colony buds outwards, forming a multi-queened "super-colony," in which ants move at extremely high densities over an ever-expanding area.
In Arnhem Land, he said he has found colonies more than half a mile long. "It's just mind-boggling to see it," he said.
A spokesman for the National Aboriginal Land Council told UPI the ant has been found around Aboriginal settlements and along creeks in the "Top End," where local Aborigines live traditional lifestyles in sparsely populated communities. He said the Aboriginal groups are worried.
This concern was summed up by Balupalu Yunupingu, a senior ranger in Arnhem Land, who told local media: "This little yellow crazy ant will destroy our culture, our land, our life."
Yellow crazy ants also have been intercepted along Australia's northeast coast, between Brisbane and Cairns and as far west as Perth.
The crazy ant (Anoplolepis gracilipes) also is known, depending on its location, as the ashinaga-ki-ari, the gramang ant, long-legged ant and Maldive ant.
Only 3-to-4 millimeters long -- less than 1-5th of an inch -- it moves in a frenetic manner, skittering around rapidly when disturbed -- hence its name.
"When their nest is disturbed, almost instantaneously they go ballistic," said O'Dowd.
O'Dowd said the ant preys on a variety of animals, from insects to large land crabs, birds, mammals, and reptiles which it attacks en masse, blinding them with a spray of formic acid.
Like many other ants, it also eats the honeydew excreted by sap-sucking aphids and scale insects, which it "farms" on stems and leaves.
The crazy ant is thought to have originated in India or western Africa. A successful hitch-hiker, it has been introduced across the subtropics and tropics, where it has arrived in cargo, ships and land transports.
O'Dowd has been studying crazy ants on Christmas Island since 1985, where they have eliminated an estimated 20 million of the island's famous red land crabs.
He said the ants are a major environmental threat because they totally displace native animals from infested areas and disrupt ecological processes.
"They also seriously affect agriculture as they cause outbreaks of sap-sucking insects which harm plants," he said. They have been responsible for destroying banana and cocoa plantations in many countries, including New Guinea and Indonesia.
The effort to eliminate crazy ants from Arnhem Land involves lacing a fish meal attractant with the intoxicant, Fipronil. The concentration of Fipronil is low, so foraging ants live long enough to return the bait to the colony and disperse it among other workers, larvae, and queens.
On Christmas Island, this method was used on a crazy ant infestation covering nearly 5,000 acres.
"We had a 99-percent knock-down rate," said O'Dowd.
Hoffmann is confident of achieving similar results. "All we need to do is load up the poison on a helicopter, and go," he said.
O'Dowd remains cautious, however. "This problem will need ongoing surveillance," he said.
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