Pachycondyla chinensis

Geographic Range

Asian needle ants ( Pachycondyla chinensis ) are native to the Palearctic region, specifically Japan, China, and Korea. These ants have been introduced to the Nearctic, Oriental, and Australian regions. They were likely accidentally introduced to the United States in the 1920s or 1930s by human travel and commerce activities. This species is invasive in the United States, particularly in the eastern states, including Alabama, Georgia, Virginia, and the Carolinas. Colonies have been found as far north as New York and Connecticut, and their range is likely expanding farther west. Asian needle ants are also present in New Zealand, South Korea, Vietnam, Thailand, Sri Lanka, India, Guam, Papua New Guinea, the Philippines, and Nepal.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
• palearctic palearctic
  • native native
• oriental oriental
  • introduced introduced
• australian australian
  • introduced introduced

Habitat

Unlike many invasive ants species, which only live in areas disturbed by human activity, Asian needle ants build nests in both disturbed areas and natural habitats. They are a temperate species, 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, often 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, nests may be built under the pavement or other man-made structures.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural

Physical Description

Asian needle ants are a dark brownish-black color, with orange-brown mandibles, legs, antennae, and stingers. Workers are 3.4 to 5.0 mm in length, while queens are significantly 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, large compound eyes, and a well-defined stinger. Their head is long, and their pronotum and mesonotum are convex in profile. Their head, pronotum, coxae, tibia, and gaster are covered in light, yellowish hair that gives them a bronze luster.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry
• venomous venomous

Development

Asian needle ants are holometabolous, undergoing complete metamorphosis. 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 males and females 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 found over the winter.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

There is little information available about the mating habits of Asian needle ants. Mating occurs in mid- to late summer. Queens only mate once in their lives. Workers do not have reproductive organs and therefore cannot mate.

• Mating System
• eusocial eusocial

Asian needle ants are polydomous, with many nests per colony. These nests are mainly polygynous, with up to 20 queens per nest. Other nests are monogynous or entirely queenless. The number of queens per nests changes throughout the season. Throughout winter and into early spring, most nests are polygynous, with about 5 queens per nest. By the middle of the summer, about 80% of nests are queenless, which is the lowest point for the year. The rate rises throughout the end of summer after alate production, before decreasing again into fall. Queens are reproductively active from early spring into summer. Most brood production is done by newly-mated queens, while queens from the previous year either die or are rejected from nests during alate production season. Rather than starting new nests, newly-mated queens are accepted into established nests after mating. Queens have a large number of ovarioles, between 18 to 36, though this varies between queens. During the reproductive season, even nests without queens have large broods. Dealate virgin queens are often found in nests, and may lay eggs that produce males.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous
• sperm-storing sperm-storing
• delayed fertilization delayed fertilization

Queens provide provisioning in their eggs. Once the eggs are laid, workers take over brood care, in which the queens do not participate. Workers provide care, feed the offspring, and transport the brood when necessary. Workers 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 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 as reproductives.

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

Lifespan/Longevity

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.

Behavior

Asian needle ants live in small colonies. They are a polydomous species, with many nests forming a colony. 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.

Asian needle ants are primarily ground-dwelling, and are rarely found on foliage, as they have trouble climbing trees and vertical surfaces. When foraging for prey, they exhibit an unusual recruitment behavior called 'tandem carrying'. When a scout returns to the nest after finding a food source or prey item, it drums its antennae on a worker as an alert. In response, the worker draws its legs in, and the scout picks the worker up with its mandibles, wrapping its mandibles around the worker's thorax between the first and second pair of legs. The carried worker stays on its back, remaining motionless, while the scout runs with it in its mandibles to the food source, where it releases the worker. Workers deconstruct the food source and bring it back to the nest. This generally occurs when the food source is a larger insect or invertebrate that cannot be brought back by one individual. Asian needle ants are diurnal, most of their foraging takes place during the day.

• Key Behaviors
• terricolous
• diurnal diurnal
• motile motile
• colonial colonial

Home Range

Among Asian needle ants, the farthest recorded foraging distance from their home nest was 10 meters. Since there are often many nests within a colony, ants move between the nests. Nests move seasonally, often from ground locations in the summer to dead trees in the winter, though these locations are most likely in the same area.

Communication and Perception

Olfaction is incredibly important in hunting prey, as Asian needle ants can detect termites and other insect prey by smell alone. Visual cues are also used when hunting and foraging. Currently, there is no evidence of Asian needle ants using any pheromones or chemicals to recruit nest mates when foraging, but physical contact between ants is used to communicate. When a scout finds a food source and returns to the nest to recruit, the scout drums its antennae on a worker, 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.

• Communication Channels
• visual visual
• tactile tactile

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Asian needle ants consume insects and other invertebrates as well as vertebrate carrion, dead insects, and rotting fruit. In their native range, these ants are termite specialists, although termites are still a significant portion of their diet in their introduced range. 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.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore

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

• Plant Foods
• fruit

Predation

Little information is available about the predators of Asian needle ants. They are likely preyed upon by small mammals, birds, and other vertebrates that live in their range. They have a potent venomous sting that they can use for defense.

Ecosystem Roles

As an invasive species in the eastern United States, Asian needle ants are displacing native ants and arthropod species. Populations of native ants are decreasing significantly in areas where Asian needle ants have invaded. This can affect members of other trophic levels, such as mammals and reptiles that feed on native species. They also cause problems for native plants by disrupting some ant-seed dispersal mutualisms, such as by displacing Aphaenogaster rudis , a significant seed dispersal mutualist. 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 another invasive species, Argentine ants , from urban areas in 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.

Asian needle ants are rarely found on foliage, which suggests that this species does not tend any honey-dew producers, unlike many other ant species. Ants of subfamily Ponerinae do not possess a crop, which makes farming honeydew difficult, as they have no way to transport it back to the nest. Since honeydew mutualisms are one way invasive ant species establish themselves in foreign areas, it is interesting that Asian needle ants do not participate. However, their termite-rich diet may help these ants establish their range, as termites are plentiful, have a high nutritional value, are easily processed, and have resilient populations, as many are produce per brood. 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 living. 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 the health and yields of domestic chickens.

Economic Importance for Humans: Positive

Asian needle ants are avid termite predators, which could be useful for curbing infestations in homes and buildings.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

Asian needle ants are an emerging health threat as they can administer a painful, venomous sting. Their venom can cause an allergic reaction with symptoms including swelling, pain, itching, and nausea. This can be treated with antihistamines, but medical attention has been required for severe reactions where humans develop hives, swelling of the tongue and face, respiratory distress, chest pain, and anaphylaxis. Fortunately, Asian needle ants are not particularly 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 arthropods, Asian needle ants are causing a loss of biodiversity in the eastern United States, which will likely worsen as their range expands.

• Negative Impacts
• injures humans
  • bites or stings
  • venomous venomous
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

Asian needle ants have no special conservation status.

Other Comments

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

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

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

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.