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Pachycondyla chinensis

What do they look like?

Asian needle ants are a dark brownish-black color, with orange-brown mandibles (appendages near their mouth), legs, antennae, and stingers. Workers are 3.4 to 5.0 mm in length, while queens are much larger at 5.0 to 6.0 mm in length. Workers are wingless, while queens and males have wings, although queens lose their wings after mating. These ants have one large petiole, which is a bump on the skinny part between their abdomen and thorax, as well as large compound eyes, and a well-defined stinger. Their head is long, and the upper area of their first two segments is rounded outward. Their head, legs, the upper part of their first segment, and their final segment are covered in light, yellowish hair, which gives them a bronze glow. (Gotoh and Ito, 2008; MacGown, 2009; Smith, 1934)

  • Range length
    3.4 to 6.0 mm
    0.13 to 0.24 in

Where do they live?

Asian needle ants (Pachycondyla chinensis) are native to the Palearctic region; they are originally from Japan, China, and Korea. Currently, these ants are also found in the Nearctic, Oriental, and Australian regions. They were probably accidentally brought to the United States in the 1920s or 1930s due to human activities. This species is invasive in the United States, especially in the eastern states, including Alabama, Georgia, Virginia, and the Carolinas. Colonies of these ants have been found as far north as New York and Connecticut, and their range is likely expanding farther west. Asian needle ants are also found in New Zealand, South Korea, Vietnam, Thailand, Sri Lanka, India, Guam, Papua New Guinea, the Philippines, and Nepal. (Guenard and Silverman, 2011; Nelder, et al., 2006; Rice and Silverman, 2013; Rodriguez-Cabal, et al., 2012)

What kind of habitat do they need?

Unlike many invasive ants species, which only live in areas disturbed by human activity, Asian needle ants build nests in both disturbed and natural habitats. They prefer mild climates and are found in deciduous forests, hardwood forests, agricultural land, and in urban and suburban areas such as office parks and backyards. Nests are usually built on the forest floor, in decaying logs or in piles of leaves. During the winter, they move into dead trees or under several inches of soil. Some colonies also live inside termite nests. In urban areas, their nests may be built under the pavement or other man-made structures. (Bednar and Silverman, 2011; Guenard and Dunn, 2010; Rice and Silverman, 2013; Rodriguez-Cabal, et al., 2012)

How do they grow?

Asian needle ants are holometabolous, which means they go through an egg, larvae, pupae, and adult stage. Their first batch of eggs is laid in early spring, and egg laying continues throughout the summer. After a couple of weeks, the eggs hatch and develop into larvae, which are present in the colony from late spring until fall. Alate pupae can be found in the nest during the middle of summer, producing winged male and female adult ants for a couple weeks in the summer. Worker pupae are present from early summer until fall; adult workers are produced throughout much of the season. No broods are produced during the winter. (Gotoh and Ito, 2008)

How do they reproduce?

There is little information available about the mating habits of Asian needle ants. These ants are eusocial, meaning that only the queens produce young. Mating occurs in mid- to late summer. Queens only mate once in their lives. Workers do not have reproductive organs and therefore cannot mate. (Gotoh and Ito, 2008)

Asian needle ants are polydomous, which means that there are many nests per colony. There may be up to 20 queens per nest, although some nests are queenless. The number of queens per nest changes throughout the season. Throughout winter and early spring, most nests have about 5 queens. By the middle of the summer, about 80% of nests are queenless, which is the lowest rate during the year. The number of queens increases towards the end of summer after alate (winged ants) are produced, before decreasing again in fall. Queens breed from early spring into summer. Most eggs are laid by newly-mated queens; queens from the previous year are rejected from the nest. Rather than founding new nests, newly-mated queens are accepted into established nests after mating. During the reproductive season, even nests without queens have large broods. Non-winged virgin queens are often found in nests and may lay eggs that produce males. (Gotoh and Ito, 2008)

  • How often does reproduction occur?
    Queens mate once in their lives after reaching adulthood.
  • Breeding season
    Mating occurs in mid- to late summer.

Queens provide nutrients in their eggs. Once the eggs are laid, workers take over care; the queens do not participate in brood care. Workers provide care, feed the offspring, and transport the brood when necessary. Workers may even move broods to nests without queens. Larvae and eggs are kept in areas with high humidity. Workers move pupae into the upper parts of the nests, as they probably need a higher temperature and lower humidity to develop into adults. Once the offspring develop into adults, brood care stops and the new adults join the colony, either as workers or breeding ants. (Gotoh and Ito, 2008)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female

How long do they live?

Queens probably only live a year, as most broods are produced by newly developed queens. Likewise, males probably do not survive long after mating and workers likely live less than a year. (Gotoh and Ito, 2008)

  • Typical lifespan
    Status: wild
    1 (high) years

How do they behave?

Asian needle ants have many nests, which form small colonies. Nest locations change seasonally. They generally nest on the forest floor from spring to fall, then move to dead trees or below the soil surface for the winter. The number of workers per nest, as well as the number of nests per colony also changes seasonally. During the winter and early spring, when the fewest nests are maintained, there are about 200 workers per nest. As the number of nests increase in the summer and during the reproductive season, the number of workers per nest decreases to about 20 per nest. More workers are present in nests with multiple queens, than in nests that are queenless. (Gotoh and Ito, 2008; Guenard and Dunn, 2010; Guenard and Silverman, 2011; Smith, 1934)

Asian needle ants are mostly found on the ground, as they have trouble climbing trees and vertical surfaces. These ants are diurnal, and do most of their foraging during the day. They perform an unusual behavior known as 'tandem carrying' when they find large prey. After finding a large prey item that cannot be carried by a single ant, such as a large insect, scouts return to their nest and drum their antennae on a nearby worker ant. In response, the worker ant draws its legs into its body so that the scout can pick it up by wrapping its mandibles around the worker's body. While the scout runs with the worker in its mandibles, the worker ant stays motionless on its back. Once they reach the food source, the scout releases the worker ant. The worker than pulls the food apart and brings it back to the nest. (Gotoh and Ito, 2008; Guenard and Dunn, 2010; Guenard and Silverman, 2011; Smith, 1934)

Home Range

Asian needle ants may forage as far as 10 meters from their home nest. Since there are often many nests within a colony, ants move between the nests. Nests move seasonally, often from the ground in the summer to dead trees in the winter, though these locations are likely in the same area. (Gotoh and Ito, 2008; Rodriguez-Cabal, et al., 2012)

How do they communicate with each other?

Their sense of smell, also known as olfaction, is very important when hunting, Asian needle ants are able to detect termites and other insect prey by smell alone. Their vision may also be important while they are hunting and foraging. Physical contact is also used to communicate between ants. When a scout finds a food source it returns to the nest and drums its antennae on a worker ant to get its attention. These ants also use a method called 'tandem carrying' when foraging. After a scout has alerted a worker to the presence of a food source, the scout picks the worker up with its mandibles and physically transports the worker to the source. (Bednar and Silverman, 2011; Guenard and Silverman, 2011)

What do they eat?

Asian needle ants consume insects and other invertebrates as well as vertebrate carrion, dead insects, and rotting fruit. In their native range, these ants specialize on termite prey. Termites make up an important part of their diet in their introduced range as well. These ants sting their prey, injecting them with venom, wait for the prey to die, and then collect the body. To collect termite prey, large numbers of ants gather outside the entrance of the termite's nest and wait for the termites to emerge. (Bednar and Silverman, 2011; Guenard and Dunn, 2010; Guenard and Silverman, 2011)

  • Animal Foods
  • carrion
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • fruit

What eats them and how do they avoid being eaten?

Little information is available about the predators of Asian needle ants, although they are likely preyed upon by small mammals, birds, and other vertebrates in their range. These ants have a venomous sting that they can use to defend themselves. (Guenard and Dunn, 2010)

What roles do they have in the ecosystem?

As an invasive species in the eastern United States, Asian needle ants are displacing native ants and other insect species. The population size of native ants decrease significantly in areas where Asian needle ants invade. This can affect other animals, such as the mammals and reptiles that feed on native species. This can also cause problems for native plants by disrupting the seed dispersal conducted by some native ant species, such as Aphaenogaster rudis, a significant seed disperser. Asian needle ants kill A. rudis and likely compete for nest sites, which prevents seed dispersal to those areas. Colonies of Asian needle ants are even displacing Argentine ants, an invasive species found in urban areas of the eastern United States. Even though Argentine ants have huge colonies and are very aggressive, Asian needle ants are able to make nests earlier in the year, when temperatures are too cold for Argentine ants, taking control of areas before Argentine ants have the opportunity. (Rice and Silverman, 2013; Rodriguez-Cabal, et al., 2012)

Asian needle ants are rarely found on plants, which suggests that this species does not tend any honey-dew producing insects, unlike many other ant species. Their taste for termites may help these ants establish their range, as termites are plentiful, have high nutritional value, and are easily processed. Asian needle ants may also live in abandoned and active termite nests, living with and eating the termites. As a termite specialist, Asian needle ants reduce termite populations in urban areas, which is convenient for humans. However, in natural habitats, reducing termite populations can decrease the rate of termite-driven decomposition. Asian needle ants are also an intermediate host of chicken tapeworms in Japan. These tapeworms can damage domestic chicken health and yields. (Bednar and Silverman, 2011; Nelder, et al., 2006; Rodriguez-Cabal, et al., 2012)

Commensal or parasitic species (or larger taxonomic groups) that use this species as a host
  • chicken tapeworms (Raillietina kashiwarensis)

Do they cause problems?

Asian needle ants can give a painful, venomous sting. Their venom can cause an allergic reaction with symptoms including swelling, pain, itching, and nausea. This is treated with antihistamines, but medical attention may be needed for people who have severe reactions such as hives, swelling of the tongue and face, respiratory distress, chest pain, and anaphylaxis. Fortunately, Asian needle ants are not usually aggressive towards humans and only sting when threatened or trapped. Asian needle ants are also an intermediate host of chicken tapeworms in Japan, which could cause economic losses. As an invasive species displacing native insects, Asian needle ants are causing a loss of biodiversity in the eastern United States, which will likely worsen as their range expands. (Nelder, et al., 2006; Rodriguez-Cabal, et al., 2012)

How do they interact with us?

Asian needle ants are avid termite predators, which could help stop termite infestations in homes and buildings. (Bednar and Silverman, 2011; Rodriguez-Cabal, et al., 2012)

  • Ways that people benefit from these animals:
  • controls pest population

Are they endangered?

Asian needle ants have no special conservation status.

Some more information...

Asian needle ants (Pachycondyla chinensis) were formerly known as Brachyponera solitaria and Euponera solitaria. (Smith, 1934)

Contributors

Angela Miner (author), Animal Diversity Web Staff, Leila Siciliano Martina (editor), Animal Diversity Web Staff.

References

Bednar, D., J. Silverman. 2011. Use of termites, Reticulitermes virginicus, as a springboard in the invasive success of a predatory ant, Pachycondyla (=Brachyponera) chinensis. Insectes Sociaux, 58/4: 459-467.

Gotoh, A., F. Ito. 2008. Seasonal cycle of colony structure in the Ponerine ant Pachycondyla chinensis in western Japan (Hymenoptera, Formicidae). Insectes Sociaux, 55/1: 98-104.

Guenard, B., R. Dunn. 2010. A New (Old), Invasive Ant in the Hardwood Forests of Eastern North America and Its Potentially Widespread Impacts. PLOS ONE, 5/7: e11614. Accessed September 22, 2013 at http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0011614.

Guenard, B., J. Silverman. 2011. Tandem carrying, a new foraging strategy in ants: description, function, and adaptive significance relative to other described foraging strategies. Naturwissenschaften, 98/8: 651-659.

MacGown, J. 2009. The Asian needle ant, Pachycondyla chinensis (Emery) (Hymenoptera: Formicidae), reported from Alabama. Midsouth Entomologist, 2/2: 88-89.

Nelder, M., E. Paysen, P. Zungoli, E. Benson. 2006. Emergence of the Introduced Ant Pachycondyla chinensis (Formicidae: Ponerinae) as a Public Health Threat in the Southeastern United States. Journal of Medical Entomology, 43/5: 1094-1098.

Rice, E., J. Silverman. 2013. Submissive behaviour and habituation facilitate entry into habitat occupied by an invasive ant. Animal Behaviour, 86/3: 497-506.

Rodriguez-Cabal, M., K. Stuble, B. Guenard, R. Dunn, N. Sanders. 2012. Disruption of ant-seed dispersal mutualisms by the invasive Asian needle ant (Pachycondyla chinensis). Biological Invasions, 14/3: 557-565.

Smith, M. 1934. Ponerine ants of the genus Euponera in the United States. Annals of the Entomological Society of America, 27: 557-564.

 
University of Michigan Museum of ZoologyNational Science Foundation

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Miner, A. 2014. "Pachycondyla chinensis" (On-line), Animal Diversity Web. Accessed October 24, 2017 at http://www.biokids.umich.edu/accounts/Pachycondyla_chinensis/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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