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
- palearctic
- oriental
- australian
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
- terrestrial
- Terrestrial Biomes
- forest
- Other Habitat Features
- urban
- suburban
- 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
- heterothermic
- bilateral symmetry
- 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
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
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
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
- sperm-storing
- 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
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-independence
-
provisioning
- female
-
protecting
- female
-
provisioning
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.
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.
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
- Animal Foods
- 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.
- chicken tapeworms ( Raillietina kashiwarensis )
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
- 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
Contributors
Angela Miner (author), Animal Diversity Web Staff, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- oriental
-
found in the oriental region of the world. In other words, India and southeast Asia.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- urban
-
living in cities and large towns, landscapes dominated by human structures and activity.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- agricultural
-
living in landscapes dominated by human agriculture.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- venomous
-
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
- eusocial
-
the condition in which individuals in a group display each of the following three traits: cooperative care of young; some individuals in the group give up reproduction and specialize in care of young; overlap of at least two generations of life stages capable of contributing to colony labor
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- sperm-storing
-
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
- delayed fertilization
-
a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- colonial
-
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
- carrion
-
flesh of dead animals.
- venomous
-
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
- causes or carries domestic animal disease
-
either directly causes, or indirectly transmits, a disease to a domestic animal
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
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.