Ants of Northern Australia

7/29/2019 Ants of Northern Australia

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Money-box sugar ants (Camponotusdenticulatus and related species) buildnest mounds with distinctive slit-shaped entrances, and forage mostlylate in the afternoon and at night.

Only one species of the infamousBull ants of the genus Myrmecia occurs in the Top End, where itis restricted to the sandstonecountry of Kakadu NationalPark. Species of  Myrmeciaarerenowned for their aggressivenessand powerful sting.

Australia has an estimated 350species of Pony ants of the genusRhytidoponera. They all have tough,heavily sculptured skins and aregeneralist predators and scavengers.

TheCoconut antCamponotus rubiginosus has a very strong coconutsmell when crushed. Itsbody is covered withlong, ne hairs.

Giant foaming ants are named after thefoam-like venom that is injected from

their powerful stings. They occur in verysmall and queenless colonies, and

are specialist predators of termites.

Some ants, such as Meranoplusunicolor , are specialistgranivores, harvesting hugenumbers of plant seeds. Theirnest middens of discarded seedhusks are a conspicuous featureof the Top End environment.

Green tree ants work together as a teamto build their nests, by pulling the edges of leaves together and ‘weaving’them using

their silk-producing larvae like tubes of glue.The silk shrinks as it dries, forming a

tight seam between the leaves.

Muscleman tree ants (species of Podomyrma) nest in cavities of livingtrees, and are exclusively arboreal.

Savanna spiny ants (Polyrhachis senilis) have silveryheads and golden abdomens, with the colours

produced by dense mats of hairs. They have longspines protecting their neck and waist.

Ants are probably the most familiar of all Australian insects, and the Top Endof the Northern Territory is blessed with an extraordinary number of them!Scientists estimate that ants make up about one-quarter of the total weightof all land animals combined, which is an incredible gure for such smallcreatures. Any hectare of typical Top End bush is likely to harbour manymillions of ants, representing 100 or more different species.

 At least 500 ant species occur in the Top End, withmore than 100 found nowhere else in the world! 

Ants: small but important!In terms of their role in ecosystems, ants are probably the most importantanimals in the Top End environment. As predators and scavengers they playa key role in nutrient cycling and energy ow, and their burrowing activitiespromote soil health.

Ants have many close relationships with plants. Many plants offer foodrewards such as nectar to entice ants to forage on them, in order to controlthe plant’s natural enemies. Other plants encourage ants to disperse theirseeds, by having a special ‘ant food’ body attached to the seed. Australiais the world’s home for such a phenomenon, with more than 1500 plantspecies relying on ants for seed dispersal. Most of the Top End’s acacias andgrevilleas have their seeds dispersed by ants.

Ants can help us manage the environmentThe great diversity and ecological importance of ants make them valuablebio-indicators of the health of our ecosystems – if ant communities

are in good shape then this is likely to indicate thatthe environment is likewise in good shape. Antsare commonly used as bio-indicators to monitorenvironmental health for a wide range of land-uses,including mining, grazing and re management.

 Ants are the life-blood of 

northern Australia’s tropical  savanna ecosystems.

TheGiant snappy ant(Odontomachus sp.) is sometimesknown locally as the Darwin bull-ant, and is a very large ant with apowerful sting. Despite its localname, it is not at all related to thetrue bull-ants of southern Australia.

More than 1500 plantspecies in Australiarely on ants forseed dispersal. Hereis an acacia seedbeing carried by theLesser-horned ponyant (Rhytidoponeraaurata) to its nest. Thisant will eat the whitefood body (elaiosome)and discard the seedundamaged.

TheNorthern meat ant (Iridomyrmex sanguineus)

is an extremely common, highly active andaggressive species in the Top End. It canoccur in huge colonies covering a hectareor more, with multiple nest entrances joined by ant ‘freeways’.

Strobe ants (species of Opisthopsis) are medium-sized, orange-and-black antsthat have a very distinctive jerky movement.

One of the best-known Top End

ants, with its distinctive leafy nests,is the Green tree ant (Oecophyllasmaragdina). It occurs throughout the

south-east Asian region, and is used asa biocontrol agent to manage pests of 

tropical horticulture.

Cannibal ants (species of Cerapachys) arespecialist predators of the brood of other ants.

CSIRO Ecosystem Sciences, Darwin NTPhone: (08) 8944 8400

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