African big-headed ants are a major threat to native ecosystems and have been successfully eradicated from several regions including Kakadu National Park, a campsite in the Daly River region, the Tiwi Islands and isolated places throughout north-east Arnhem Land. There is also an eradication program on Lord Howe Island, now in its final stages.
African big headed ants are a major pest
African big-headed ants (Pheidole megacephala) are listed as one of the 100 worst pests in the world.
The ants are a major threat to biodiversity and the environment because they can readily out-compete and displace native invertebrates, even to the point of local extinction.
Rainforest ecosystems are most at risk. For example, in the Howard Springs Nature Park in the Northern Territory, African big-headed ants have completely displaced all native ant species and reduced the populations of other invertebrates by up to 80 per cent.
The major (soldier) workers have huge heads, contributing almost half of the body size. The minor workers, which are seen more often, are small (about 2 mm) and vary in colour from light to dark brown.
African big-headed ants are slow moving, do not bite or sting, and have no smell when crushed.
Since the early 2000s CSIRO has been working in collaboration with land managers, particularly Aboriginal Ranger groups, across northern Australia to eradicate African big headed ant from remote locations.
In the early 2000s, CSIRO and Kakadu National Park staff eradiated African Big-headed ants from a 30 hectare site within the World Heritage listed site.
Following on from the success in Kakadu, CSIRO worked with the MalakMalak Rangers from the Daly River region south of Darwin to eradicate a significant population.
Further work with the Dhimurru Rangers has resulted in three populations of African big-headed ants being eradicated from north-east Arnhem Land, while the Tiwi Land Rangers have eradicated the ant from Tiwi Islands north of Darwin.
In 2012 CSIRO was engaged by the Lord Howe Island Board to provide expertise and oversight for the African big-headed ant eradication program on Lord Howe Island. To date, all known infestations of the ant have been treated, and most locations have already been declared free of the ant. The last known surviving ants were recently detected on a single property in March 2016, and the infested area has been re-treated. If no more ants are found in the next two years, the ant will be declared eradicated from Lord Howe Island in March 2018.
Listen to the podcast with Dr Ben Hoffman, speaking about the African Big-headed ant eradication program on Lord Howe Island.
Pests in paradise: saving Lord Howe Island from the ants
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