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C
Carpenter Ants
(Camponotus)
Natacha Rossi
1
and Heike Feldhaar
2
1
Laboratory of Experimental and Comparative
Ethology (LEEC), University of Paris 13,
Villetaneuse, France
2
Animal Ecology I, Bayreuth Center for Ecology
and Environmental Research (BayCEER),
University of Bayreuth, Bayreuth, Germany
Camponotus, the most species-rich ant genus,
has a worldwide distribution. Its highest diversity
and abundance is reached in tropical forests
and savannah habitats at low latitudes. Colonies
are often highly conspicuous due to the large
workers and often very large colony sizes. Most
species have a dimorphic worker caste with
smaller minor and distinctly larger, big-headed
major workers. Nests of Camponotus can be
constructed in soil or underneath stones, in dead
wood, or in live plants. Some species in tropical
regions can construct delicate silken nests on
the undersides of leaves. In contrast to most
other ants, several Camponotus species are able
to excavate cavities in solid wood (including
wooden structures of houses) as nesting space,
which has earned the genus the common name
carpenter ants.
Systematics and Evolution
Currently there are more than 1500 described
species of Camponotus in around 46 subgenera.
However, a detailed taxonomic analysis of the
status of many species as well as the subgenera
is overdue. While widespread species may
have many different intraspecic names and
junior synonyms (e.g., the African Camponotus
maculatus), other species may still go undetected
due to little morphological variation. The sheer
number of species in tropical and subtropical
regions renders a taxonomic revision of the
genus among the major challenges in ant taxon-
omy, one that awaits a very determined
myrmecologist.
Camponotus belongs to the species-rich
tribe Camponotini, which also includes the
genera Calomyrmex,Echinopla,Opisthopsis,
Overbeckia, and Polyrhachis. All species
of this tribe examined so far harbor the
vertically transmitted endosymbiotic bacterium
Blochmannia, which plays an important role in
nutritional upgrading (see below). A recent
phylogenomic study has shown that Camponotus
is not monophyletic. Blaimer and coworkers [1]
suggested that the former subgenera Colobopsis
and Dinomyrmex should be elevated to genus
level. Colobopsis includes species with workers
possessing phragmotic heads, which they use to
© Springer Nature Switzerland AG 2020
C. Starr (ed.), Encyclopedia of Social Insects,
https://doi.org/10.1007/978-3-319-90306-4_177-1
plug nest entrances, or explodingants such
as Co. saundersi. The latter and related species
possess a greatly hypertrophied mandibular gland
that can rupture due to muscular contractions
together with the intersegmental membranes,
releasing sticky secretions explosively onto an
enemy. This immobilizes the enemy effectively,
but it also kills the exploding ant [3]. The genus
Dinomyrmex now includes the single Southeast
Asian species D. gigas, the formerly largest
Camponotus species (and one of the largest ants
in the world) with major workers being around
3 cm in body length.
Morphology and Natural History
Camponotus workers can be recognized by their
12-segmented antennae and the insertion of the
antenna being well behind the clypeal margin.
In contrast to Polyrhachis,Camponotus never
have spines on the thorax. A peculiarity of
Camponotus (with few exceptions) is the loss of
the metapleural gland. This gland is one of the
autapomorphies of the family Formicidae and
produces antimicrobial substances. The loss of
the gland in Camponotus and a few closely
related genera is thought to be associated with
an arboreal lifestyle and the ability to weave
nests in the canopy with larval silk. Many species
of carpenter ants have an arboreal lifestyle and
forage in the canopy of trees. Similar to other
formicines, Camponotus ants have a large crop
that allows the transport and storage of large
quantities of liquid food, such as extraoral
nectar or honeydew collected from plant sap-
sucking insects (Fig. 1).
Species with large colonies can dominate an
ant community, displacing other ants from
food sources. Other species of Camponotus are
regarded as ecologically subordinate, in which
one to a few workers forage opportunistically.
They nd food sources fast but make no attempt
to defend them against other ants. Many species
of Camponotus are nocturnal or at least still active
at night. Since few ant genera show a strong
specialization to nighttime activity, Camponotus
are a major feature in a diurnal/nocturnal species
turnover within ant communities. In Southeast
Asia, for example, trophobionts that are visited
by Polyrhachis in the daytime may be visited by
Camponotus at night.
The majority of Camponotus species workers
are dimorphic, and task allocation is linked to
marked differences in worker morphology and
body size (worker polyethism) (Fig. 2). The
smaller minor workers tend to perform more
tasks related to brood care and foraging, while
the larger major workers play a more important
role in colony defense.InCamponotus
pennsylvanicus the exploitation of honeydew is
based on a specialization of worker subcastes. The
minors, with a head width of 12 mm, function as
guards of the aphid colony and solicit the aphids
to produce droplets of honeydew. The honeydew
is then transferred to the major workers whose
head has a width of 23 mm. The majors,
which are unable to efciently solicit aphids
because of their size, are specialized in the
transport of honeydew, moving back and forth
between the aphid colony and the nest as
tankers.As they can store ve to six times
more sugary liquids in their crop than minor
workers, this division of labor leads to energy
saving.
Carpenter Ants Have the Ability to
Excavate Wood
While most wood-nesting ants utilize preformed
cavities or excavate softer, already decomposing
Carpenter Ants, Fig. 1 Camponotus sericeiventris
major worker feeding on a droplet of honeydew
2 Carpenter Ants
wood, larger Camponotus species are also able
to excavate solid wood in living tree trunks. The
ability to destroy hardwood makes some carpenter
ants serious household or structural pests. For
instance, C. vagus, a species with large workers
occurring in Central and Southern Europe, lives in
old tree trunks. It can also penetrate homes and
attack wooden frames by taking advantage of
holes already drilled by wood-feeding beetles or
termites. C. ligniperda is another large carpenter
ant found in Northern Europe in upland forests.
Its workers remove the soft spring wood and do
not remove the harder wood, formed later in the
season. The resulting nest presents a system of
concentric chambers, separated by partitions that
are left intact (Fig. 3). Ants are unable to digest
wood. However, fungi, other microorganisms,
and wood-boring insects might play a role in
wood decay and wood detoxication, thereby
facilitating excavation of solid wood.
Interactions with Plants
Carpenter ants have a broad range of mutualistic
interactions with plants, including pollination,
seed dispersal, and aid in establishment of seed-
lings, or protection of plants against herbivores.
Most ants are poor pollinators, because their
metapleural glands produce antibacterial and
antifungal components that damage the pollen
membrane. However, at more than 2500 m
above sea level in the Sierra Nevada, USA, the
only pollinators to visit plants are ants. Due to
the lack of the metapleural gland, Camponotus
visiting owers can transport pollen without
damaging it [5].
Southeast Asian and American tropical
rainforest canopies house plenty of vascular
epiphytes. A few dozen of these epiphytes
(including some orchids and bromeliads) are
totally dependent on ants for their establishment
and proliferation. As the plantsseeds are actively
collected by the ants and then planted into their
carton nests on branches of trees, where they
germinate, these associations are called ant
gardens.Carton nests consisting of plant bers
and soil or detritus allow the ants to construct
their own nesting space independent of preformed
cavities in plants. Since carton nest building as
well as seed collection and planting behaviors
are not very widespread, only a few species
of ants are able to initiate these ant gardens.
The plants benet from the association through
dispersal of seeds, as well as protection from
herbivores by patrolling ants and fertilization,
since the carton is enriched in nitrogen, phospho-
rous, and potassium. The plants stabilize the nest
carton and anchor it on the branches with their
roots, while leaves protect against heavy rain and
may increase nesting space within leaves. Plant
seeds are selectively retrieved by the ants, most
likely based on chemical cues. In ant gardens of C.
irritabilis in Malaya and Sumatra, Hoya elliptica
(Apocynaceae) is planted by the ants. Growth is
strongly controlled by the ants to optimize the size
of nest chambers in accordance with the colonys
needs [9]. Ant gardens initiated by C. femoratus in
tropical South America can include other ant spe-
cies such as Crematogaster levior. Such nest
sharing is called parabiosis (see below).
The Bornean ant species Camponotus schmitzi
has an unlikely liaison with the carnivorous
pitcher plant Nepenthes bicalcarata. While the
plant is a deadly trap for many insects slipping
on the peristome and dropping into the pitcher, C.
schmitzi workers are able to enter the pitcher,
swim and dive in the pitcher uid, and then
crawl out of the pitcher again due to specic
Carpenter Ants, Fig. 2 Nest of Camponotus oridanus,
the Florida carpenter ant, with the queen on the left
surrounded by major and minor workers
Carpenter Ants 3
adaptations of their feet that enable walking on the
slippery surface. This ant species is obligately
associated with the pitcher plant and nests in its
hollow tendrils. The ants collect nectar that the
carnivorous plant presents at two spur-like exten-
sions protruding from the lid of the pitcher. How-
ever, the ants also supplement their food resources
with insect prey items retrieved from the pitcher!
The plant in turn benets from its ant partner
in several ways. The workers defend the plant
against Alcidodes weevils that can destroy the
pitchers. In addition, the ants provide nitrogen-
rich waste products in the form of remains of
workers and feces, which enhance plant growth
[2].
Interactions with Aphids and Other
Insects
Many Camponotus species maintain mutualistic
relationships with trophobionts. These are plant
sap-sucking Hemiptera, whose sugary exudates
(honeydew) are collected by workers. Most
of these associations are opportunistic and facul-
tative mutualisms that are not species-specic.
In return for the honeydew, the ants defend
the trophobionts against enemies and competing
ants. In addition, some Hemiptera gain a hygienic
benet. They rid themselves of the honeydew
that might otherwise foster mold proliferation
due to the fermentation of sugars, which could
harm both the plants and the hemipteran. While
most hemipterans can ick the honeydew away,
others need to be cleaned by ants who directly
remove the droplets of honeydew [8].
The evolved mutualism in this case has led to
particular behaviors in the two partners: ants can
request honeydew from the aphid by antennal
solicitation, and aphids can signal to ants by pro-
ducing an anal droplet of honeydew and
reabsorbing it several times (e.g., Euphyonarthex
phyllostoma and C. brutus).
Many buttery species of the families
Lycaenidae and Riodinidae maintain symbiotic
relationships with ants, including species
of Camponotus. Mutualistic associations can be
facultative, in which the caterpillars do not require
ant attendance, or obligate, in which they do
require ants for survival under eld conditions.
The caterpillars show specic adaptations related
to ant attendance. First, the cuticle is much
thicker, and the head can be retracted, which
sometimes gives lycaenid larvae a resemblance
to limpets. This is regarded as a defense against
ant bites. Ants are attracted to caterpillars by
substances mimicking alarm pheromones,
emitted by specialized organs. Caterpillars benet
from the vigilance of ants against predators and
parasites. Ants, in turn, are rewarded by droplets
containing sugar and amino acids from the cater-
pillarsabdominal gland [7].
However, not all relationships with
Lepidoptera are to mutual benet. For instance,
Carpenter Ants, Fig.
3Damage in wood caused
by carpenter ants. (Photos
by Uwe Noldt)
4 Carpenter Ants
the lycaenid butteryNiphanda fusca has an
obligate parasitic relationship with its host ant,
C. japonica. The caterpillars enter the ants
nest, where they are fed mouth to mouth
and raised by adult ants until pupation. This
cuckoo-like interaction is facilitated by chemical
mimicry of the cuticular prole of their host [7].
A few species of Camponotus are associated
with other ant species with whom they share a
nest or whose foraging trails they can follow.
Nest sharing (parabiosis) often involves a
Camponotus species and a member of the genus
Crematogaster. An association of species of
these two genera has evolved repeatedly in
both the New World and Old World tropics.
Parabiosis has been shown to be a mutually
benecial interspecic association. Carpenter
ants can provide nest space in the form of ant
gardens (see above) and may be better at
defending the nest than the associated
Crematogaster species. In turn, Camponotus
benets from the parabiosis by following
pheromone trails laid by Crematogaster workers.
Thus, food sources discovered by Crematogaster
can be exploited by Camponotus. Workers of
the two colonies in a parabiotic association
tolerate each other. Absence of aggression is
achieved by two different mechanisms. First,
parabiotic ants possess longer cuticular hydro-
carbon molecules than non-parabiotic species.
These substances allow discrimination between
nestmates and intruders. Longer-chained hydro-
carbons are less volatile and can thus potentially
be perceived less well, so that parabiotic ants
provide fewer recognition cues. Non-nestmate
colonies of the partner species are therefore
often tolerated. Second, at least the paleotropic
Crematogaster modiglianii produces substances
(so called crematoenones) that reduce the aggres-
sion of its partner Camponotus rufemur [6].
Endosymbiotic Bacteria Help Overcome
Nitrogen Limitation in Camponotus Ants
Due to the arboreal lifestyle and manifold
associations with trophobionts, carpenter ants
often rely on resources that are directly
produced by plants, such as extraoral nectar,
or indirectly on honeydew produced by
trophobionts. In addition, workers often forage
on leaf surfaces and collect pollen or fungal
hyphae. Thus, carpenter ants feed at a relatively
low trophic level with a diet rich in carbohydrates
but low in protein. Endosymbiotic bacteria
that are housed intracellularly in the midgut
tissue help to overcome this limitation. The endo-
symbiotic bacteria Blochmannia are obligately
associated with Camponotus and related genera
such as Polyrhachis.Blochmannia is transmitted
from generation to generation via the eggs. In
spite of its strongly reduced genome, this
proteobacterium can provide its host ant with
essential amino acids, and it may play an
important role in the recycling of nitrogenous
metabolic waste products. Blochmannia enables
Camponotus to metabolize urea and hence use
nitrogen sources inaccessible to most other ant
species. Provisioning of essential amino acids
seems to be most important directly after
the hatching of pupae, since relatively large
amounts of essential amino acids are required
for the development and tanning of the cuticle
in adult ants [4].
Cross-References
Ant Gardens
Colony Defense
Communication, Alarm
Communication, Pheromones
Crematogaster
Cuticular Hydrocarbons
Extra-Floral Nectaries
Honeydew
Pollination
Polyrhachis
Worker Polyethism
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methods outperform traditional multi-locus approaches
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6 Carpenter Ants
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Carpenter ants (genus Camponotus) are considered to be omnivores. Nonetheless, the genome sequence of Blochmannia floridanus, the obligate intracellular endosymbiont of Camponotus floridanus, suggests a function in nutritional upgrading of host resources by the bacterium. Thus, the strongly reduced genome of the endosymbiont retains genes for all subunits of a functional urease, as well as those for biosynthetic pathways for all but one (arginine) of the amino acids essential to the host. Nutritional upgrading by Blochmannia was tested in 90-day feeding experiments with brood-raising in worker-groups on chemically defined diets with and without essential amino acids and treated or not with antibiotics. Control groups were fed with cockroaches, honey water and Bhatkar agar. Worker-groups were provided with brood collected from the queenright mother-colonies (45 eggs and 45 first instar larvae each). Brood production did not differ significantly between groups of symbiotic workers on diets with and without essential amino acids. However, aposymbiotic worker groups raised significantly less brood on a diet lacking essential amino acids. Reduced brood production by aposymbiotic workers was compensated when those groups were provided with essential amino acids in their diet. Decrease of endosymbionts due to treatment with antibiotic was monitored by qRT-PCR and FISH after the 90-day experimental period. Urease function was confirmed by feeding experiments using 15N-labelled urea. GC-MS analysis of 15N-enrichment of free amino acids in workers revealed significant labelling of the non-essential amino acids alanine, glycine, aspartic acid, and glutamic acid, as well as of the essential amino acids methionine and phenylalanine. Our results show that endosymbiotic Blochmannia nutritionally upgrade the diet of C. floridanus hosts to provide essential amino acids, and that it may also play a role in nitrogen recycling via its functional urease. Blochmannia may confer a significant fitness advantage via nutritional upgrading by enhancing competitive ability of Camponotus with other ant species lacking such an endosymbiont. Domestication of the endosymbiont may have facilitated the evolutionary success of the genus Camponotus.
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In primary lowland rain forest in Brunei Darussalam, we studied arboreal ant communities to evaluate whether densities and spacing of spatially territorial taxa along 2.9 km of well-studied trails are consistent with existence of a continuous mosaic of dominant ants. A median intercolony distance of 24.5 m, about twice or less distances over which colonies of most included species regularly ranged, suggested a relatively continuous mosaic. Despite relying on nesting sites in preformed plant cavities, carpenter ants contributed > 70 percent of mapped colonies. Most belonged to the Camponotus (Colobopsis) cylindricus (COCY) complex, including SE Asia's ‘exploding’ ants. Their lack of aggression against certain Polyrhachis species was associated with interspecific territory sharing by members of the two groups, and with a dominance-discovery trade-off. Experimental approaches yielded evidence for two putative contributors to positive association. Larger-bodied Polyrhachis parasitize food-finding abilities of smaller, more populous Camponotus workers, and the two taxa cooperate in territorial defense. Highly territorial and predatory weaver ants (Oecophylla smaragdina) were an important component of the ant mosaic in primary forest, second only to codominant COCY and Polyrhachis taxa. Members of the genus Crematogaster were significantly associated with Oecophylla in baiting censuses and regularly monopolized near-nest baits to the exclusion of weaver ants. Litter ant abundances differed between territories of Oecophylla and less predatory COCY species, but direction of difference was inconsistent over time. The densely packed mosaic of spatially territorial, and differentially predatory, taxa in Bornean rain forest likely contributes to spatial variation in ant effects on plant and arthropod communities.
  • A Weissflog
  • E Kaufmann
  • U Maschwitz
Weissflog, A., Kaufmann, E., & Maschwitz, U. (2017). Ant gardens of Camponotus (Myrmotarsus) irritabilis (Hymenoptera: Formicidae: Formicinae) and Hoya elliptica (Apocynaceae) in Southeast Asia. Asian Myrmecology, 9, e009001.