Yellow crazy ants invade Northern Australia

[Orstio]

Northern Australia has been invaded by one of the world's worst species of ant, which could affect human health and damage the environment, agriculture, and the economy.

"This little Yellow Crazy ant will destroy our culture, our land, our life," says Balupalu Yunupingu, Dhimurru senior ranger, north-east Arnhem Land.

The Yellow Crazy ant is recognised by the Global Invasive Species Programme as one of the world's worst invaders, and represents a major environmental and economic threat to northern Australia.

CSIRO research fellow, Dr Ben Hoffmann, says Yellow Crazy ants form multi-queened 'super-colonies' in which ants occur at extremely high densities over large areas.

"The density of foraging worker ants in super-colonies is amazing, reaching around 1000 per square metre or 79 million per hectare of bush," he says.

Dr Hoffmann says the ants are a threat to human health as their acid spray can send people and animals blind.

"When the ants are swarming people get acid on their hands and can accidentally rub it into their eyes. This is particularly a concern for infants", he said.

Dr Hoffmann says the ants are a major environmental threat as they totally displace native animals from infested areas, and seriously disrupt ecological processes.

"They are also a serious pest of agriculture as they cause outbreaks of sap-sucking insects which harm plants," he says.

The Yellow Crazy ant (Anoplolepis gracilipes) is believed to have come from India and was accidentally introduced by people to Australia probably about 60 to 70 years ago.

Dhimurru Land Management Aboriginal Corporation Senior Cultural Adviser, Nanikiya Munungurritj, says the ant has been found around human settlements, along creeks and in shaded areas on the Gove peninsula in eastern Arnhem Land.

"Yellow Crazy ants need help from people to move across country. If the ants had found their way into densely populated areas instead of this remote area they would have already spread right across the country", he says.

"People should be aware of Crazy ants. We need to track their locations and treat them before they get out of hand".

Yellow Crazy ants are also a serious pest in homes. The ants nest in all kinds of materials, from potting mix to packaging, making it very easy for them to be accidentally transported by people.

Northern Land Council project officer Mark Ashley says the threat of Yellow Crazy ants should not be underestimated.

"These ants have the capacity to spread from Broome in Western Australia across to Queensland", he says.

"We have an opportunity now to do something about them while their distribution is limited. It will cost money but if we act quickly it will be far more cost efficient than if we wait 10 years."

On Christmas Island, Yellow Crazy ants have completely eliminated the Island's famous red land crabs in areas where super-colonies exist. An estimated 15-20 million red crabs have been killed since crazy ant super-colonies were first reported in 1989, a decline of 30 per cent of the crab population. This had led to major changes in the island's rainforest ecosystem, and is threatening a range of rare and endangered species on the island.

Mr Munungurritj says the Dhimurru Land Management Aboriginal Corporation, the Northern Land Council and CSIRO have developed a proposal for a control program.

"We want to keep the country as it is. The way it was always long before these Crazy ants came. So we would like to eradicate them as soon as possible - on the spot", he says.

Mr Munungurritj, Mr Ashley and Dr Hoffmann will be presenting a joint seminar on Yellow Crazy ants in northern Australia at CSIRO today (Friday) in Darwin.