Invasion is everyone’s war when little fire ants are marching south

Invasive species usually wreak havoc in rural Australia. The imposition of an emergency biosecurity order following the discovery of an imported red fire ant nest in the NSW’s Northern Rivers about 100 kilometres south of the Queensland border brings it closer to home.

A five-kilometre zone has beenimposed around the town of Wardell while sniffer dogs and baiting continue in an effort to find and eradicate other colonies. The discovery followed an attack on a gardener.

Unlike many other invasive species,fire ants can kill. They were introduced to the US state of Alabama in the 1930s and spread across America,wheremore than 80 deaths have been recorded. Their bite typically causes a burning sensation that lasts up to an hour and,in some cases,a fatal anaphylactic shock.

The Wardell discovery comes two months after fire ant nests were detected for the first time in the state,at South Murwillumbah,13 kilometres south of the border.

Fire ants are native to South America. They were discovered in Australia in 2001. They arrived at Brisbane by boat. The insects will be able to establish colonies in 99 per cent of mainland Australia,and a nationwide infestation is feared if the ants enter the Murray Darling Basin network and form rafts in the river system. The federal government is co-ordinating a national fire ant eradication program and there are plans for a $600 million effort in Queensland to reduce the threat to the nation but Western Australia,South Australia,Tasmania and the Northern Territory are yet to commit their share of the funds.

Previously,colonies have beeneradicated in Port Botany,NSW,and,more recently,in Fremantle,WA. Shortly after the Wardell discovery,Australia Post in Tasmania last week found one fire ant among plant material imported from the mainland.

Since European settlement,Australia has been a home away from home for invasive species. The cane toad is the most notorious,partly because its arrival was such a massive own goal that it served as a kind of national joke about Queensland. Imported from Hawaii in 1935 to eradicate beetles from sugar crops,Bufo marinus escaped from an experimental farm outside Gordonvale in far north Queensland and hopped into NSW,the Northern Territory and Western Australia. The toads did not like the beetles but devoured everything they could and were poisonous to local fauna.

Before that,rabbits ate much of Australia dry after being released in Victoria by the Western District squattocracy to be hunted and bring a bit of England to the bush. The myxoma virus controlled the rabbit plagues,but they remain our most destructive invasive species,destroying plants and competing with native grazing animals for food. Meanwhile,other newcomers – cats,pigs,goats,foxes,rays,cattle and camels – continue to devastate the country or slaughter local species.

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In concert with the introduced animals,plants have proved equally dangerous. Blackberry,lantana and root rot fungus are playing havoc with local flora. A cactus,prickly pear,used for garden decoration,raced through rural Australia,infecting one million hectares a year until the cactoblastis moth was introduced in the 1920s in an exercise still regarded as the world’s most successful pest plant repression by biological means.

The fire ant invasion is unlikely to be so readily stopped. The insects,which are hard to identify,will keep coming south. While there is debate on government funding to fight the ant colonies,the best thing the people of northern NSW on the front line can do is to learn to spot the enemy.

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