The Asian Needle Ant is an invasive threat every bit as worrying as its name would suggest.
The Asian needle ant, Brachyponera chinensis, is an invasive ant with a difference. In areas it invades, not only does it displace native ants, but predates on termites. Most invasive ants are particularly adept at exploiting disturbed areas, but the Asian needle ant will also invade undisturbed native forests, where it can have a significant impact on native ecosystems. Endemic to Asia – China, Taiwan, North and South Korea, and Japan – it has invaded Russia, Georgia and the United States. Although not known to be in Australia, it is certainly an ant we need to keep out of the country and pest managers should know how to identify this potential invader.
The Asian needle ant is a small dark brown/black ant, 4-5 mm long. As its name suggests it has a very potent sting, which can also result in anaphylactic shock! In the US they are sometimes confused with red imported fire ants and are similarly seen as a public health threat. They nest in leaf litter or moist soil under rocks and logs, but also under pavers and in lawns. They can produce multi-nest, multi-queen colonies, although many of the nests in a colony are queenless. They also produce alates that have a dispersal flight.
It is a predatory ant, typically feeding on small invertebrates, including termites. Indeed, the Asian needle ant does not occur in areas lacking in Rhinotermitidae termites. They are also known to enter buildings to scavenge for food and are sometimes attracted to sugar when available. They also appear to have an unusual foraging pattern as they are not known to produce trail pheromones or develop foraging trails. Instead, they adopt a slow recruitment process called ‘tandem carrying’, whereby foragers who have found a food source carry nestmates from the nest back to the food source, which is then taken back to the nest.1
From an environmental point of view, they are a significant threat. In the US, in areas of native forest where it has become established, it has displaced many native species. It also seems capable of displacing Argentine ants, another invasive ant, which nests in similar locations. Surveys in North Carolina have shown that Asian needle ants have become twice as abundant as all the native ants combined, and the number of native ant species has reduced by a third. With native ants a significant contributor to seed dispersal, it could have a significant impact on plant species composition and therefore the local ecosystem. The apparent preference and specialisation in termite predation also means that environments with a significant termite fauna will provide the Asian needle ant with the ideal resources for rapid colonisation. A significant impact on termite numbers will also impact decomposition rates and soil structure.
Controlling such an unusual ant is not straightforward. Not surprisingly, normal ant baits are not always effective, partly due to their unique food preferences and partly due to their unusual foraging behaviour and lack of mass recruitment to food sources. However, researchers have augmented a commercial granular bait with termite extracts (Reticulitermes flavipes) to good effect in laboratory trials, with increased acceptance and speed of colony control. However, no significant difference was measured in the field, and is the subject of further research.2
The Asian needle ant already thrives in a wide range of climates (as long as termites are present) and climate change has been predicted to increase the habitat suitable to Asian needle ant invasion by 65%.3 This makes large areas of coastal Australia a potential paradise for the Asian needle ant, should it arrive.
More information on ants.
1 Guenard, B and Silverman, J (2011). Tandem carrying, a new foraging strategy in ants: Description, function, and adaptive significance relative to other described foraging strategies. The Science of Nature 98(8):651-9.
2 Buczkowski, G (2023). Termite cuticular extracts improve acceptance of bait for controlling invasive Asian needle ants, Brachyponera chinensis. Pest Management Science 79(10):4004-4010.
3 Bertelsmeier C, Guenard B and Courchamp F, Climate change may boost the invasion of the Asian needle ant. PLoS One 8:e75438 (2013).
