Ant

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Ants Fossil range: Cretaceous - Recent
Meat eater ant feeding on honey
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Hymenoptera Suborder: Apocrita Superfamily: Vespoidea Family: Formicidae Latreille, 1809
Subfamilies
Aenictogitoninae Agroecomyrmecinae Amblyoponinae (incl. "Apomyrminae") Aneuretinae Cerapachyinae Dolichoderinae Ecitoninae (incl. "Dorylinae" and "Aenictinae") Ectatomminae Formicinae Heteroponerinae Leptanillinae Leptanilloidinae Myrmeciinae (incl. "Nothomyrmeciinae") Myrmicinae Paraponerinae Ponerinae Proceratiinae Pseudomyrmecinae Cladogram of ant subfamilies Leptanillinae Amblyoponinae Paraponerinae Agroecomyrmecinae Ponerinae Proceratiinae Ecitoninae Aenictinae Dorylini Aenictogitoninae Cerapachyinae* Leptanilloidinae Dolichoderinae Aneuretinae Pseudomyrmecinae Myrmeciinae Ectatomminae Heteroponerinae Myrmicinae Formicinae A phylogeny of the extant ant subfamilies.[1] *Cerapachyinae is paraphyletic

Ants are social insects of the family Formicidae and, along with the related families of wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. Today, more than 12,000 species are classified. They are easily identified by their elbowed antennae and a distinctive node-like structure forming a slender waist.

The highly organised colonies and nests of ants may consist of millions of individuals. Individuals in a colony are mostly sterile females ("workers", "soldiers", and other castes) with some fertile males ("drones") and one or more fertile females ("queens"). Colonies can occupy and use a wide area of land to support themselves. Ant colonies are sometimes described as superorganisms because the colony appears to operate as a unified entity.^[2]

Ants have colonised almost every landmass on Earth. The only places lacking indigenous ants are remote or inhospitable islands. Ants dominate most ecosystems, forming 15–20% of the terrestrial animal biomass.^[3] Their success has been attributed to their social structure, ability to modify their habitats, tap resources and defend themselves. Their long co-evolution with other species has led to mimetic, commensal, parasitic and mutualistic relationships.^[4]

Ant societies have division of labour, communication between individuals and an ability to solve complex problems.^[5] These parallels with human societies have long been an inspiration and subject of study for man. Many human cultures make use of ants in cuisine, medication and rituals. Some species are valued in their role as biological pest control agents.^[6] However, the ability to exploit resources brings ants into conflict with humans, they can damage crops and invade buildings. The accidental introduction of species into new areas and a tendency to sting has made some ants major pests.^[7]

Contents 1 Taxonomy and evolution 1.1 Etymology 1.2 Distribution and diversity 2 Morphology 2.1 Polymorphism 3 Development 4 Behaviour and ecology 4.1 Communication 4.2 Defence 4.3 Learning 4.4 Nest construction 4.5 Food cultivation 4.6 Navigation 4.7 Locomotion 4.8 Cooperation and competition 4.9 Relationships with other species 5 Relationship with humans 5.1 As food 5.2 As pests 5.3 In science and technology 5.4 In culture 6 Citations 7 General references 8 External links 8.1 General 8.2 Pest management 8.3 Images 8.4 Regional

[edit] Taxonomy and evolution

Vespoidea Sierolomorphidae Tiphiidae Sapygidae Mutillidae Pompilidae Rhopalosomatidae Formicidae Vespidae Scoliidae Phylogenetic position of the Formicidae.[8]

The Formicidae family belongs to the order Hymenoptera, which also includes sawflies, bees and wasps. Ants are evolved from a lineage within the vespoid wasps. Phylogenetic analysis suggests that ants arose in the mid-Cretaceous period about 110 to 130 million years ago. After the rise of flowering plants about 100 million years ago, they diversified and assumed ecological dominance around 60 million years ago.^[9][10][11]

In 1966, E. O. Wilson and others obtained the first amber fossil remains of an ant (Sphecomyrma freyi) from the Cretaceous period. The specimen was trapped in amber from New Jersey and is more than 80 million years old. This species provides the clearest evidence of a link between modern ants and non-social wasps. Cretaceous ants shared both wasp-like and modern ant-like characteristics.^[12]

During the Cretaceous period, only a few species of primitive ants ranged widely on the super-continent Laurasia (the northern hemisphere). They were scarce in comparison to other insects, representing about 1% of the population. Ants became dominant after adaptive radiation at the beginning of the Tertiary period. By the Oligocene and Miocene ants had come to represent 20–40% of all insects found in major fossil deposits. Of the species that lived in the Eocene epoch, one of approximately ten genera survive to the present. Of the genera, 56% are represented in Baltic amber fossils (early Oligocene), and 92% of the genera represented in Dominican amber fossils (apparently early Miocene) still survive today.^[13][9]

Termites, sometimes called white ants, are not closely related to ants, although they have similar social structures. Velvet ants, although resembling large ants, are wingless female wasps.^[14][15]

[edit] Etymology

The word ant is derived from ante of Middle English which is derived from æmette and emmett of Old English and is related to the Old High German āmeiza from which comes ameise, the German word for ant.^[16] The family name Formicidae is derived from the Latin formica for ant.

[edit] Distribution and diversity

Region	Number of species [17]
Neotropics	2162
Nearctic	580
Europe	180
Africa	2500
Asia	2080
Melanesia	275
Australia	985
Polynesia	42

Ants are found on all continents except Antarctica. Many islands such as Greenland, Iceland, parts of Polynesia and the Hawaiian Islands lack native ant species.^[18][19] Within the environments where they occur, they have been estimated to contribute 15–20% (on average and nearly 25% in the tropics) of the total terrestrial animal biomass, which exceeds that of the vertebrates.^[3]

Ants range in size from 0.75 to 52 millimetres (0.030 to 2.0 in).^[20][21] Their colours vary; most are red or black, green is less common, some tropical groups have a metallic lustre. More than 12,000 species are currently recognised, with the greatest diversity in the tropics. Taxonomic studies continue to resolve the classification and systematics of ants. Online databases of ant species, including AntBase and the Hymenoptera Name Server, help in keeping track of the known and newly described species.^[22] The relative ease with which ants can be sampled and studied in ecosystems has made them useful as indicator species in biodiversity studies.^[23][24]

[edit] Morphology

Ants are distinct in their morphology from other insects by having elbowed antennae, metapleural glands, and by having the second abdominal segment strongly constricted into a node-like petiole, forming a narrow waist between their mesosoma (thorax plus the first abdominal segment, which is fused to it) and gaster (abdomen less the abdominal segments in the petiole). The petiole can be formed by one or two nodes (only the second, or the second and third abdominal segments). Ants appear to have three clear divisions which are the head, mesosoma and metasoma or gaster.^[25]

Ants, like other insects, have an exoskeleton, an external covering that provides a protective casing around the body and a place to attach muscles, in contrast to the internal skeletons of humans and other vertebrates. Insects do not have lungs, but oxygen and other gases like carbon dioxide pass through their exoskeleton through tiny valves called spiracles. Insects also lack closed blood vessels but have a long, thin, perforated tube along the top of the body (called the "dorsal aorta") that functions like a heart in that it pumps haemolymph towards the head, thus creating some circulation of the internal fluids. Their nervous system consists of a ventral nerve cord running the length of the body, with several ganglia and branches along the way into each extremity.^[26]

The head of an ant has many sensory organs. Ants, like most insects, have compound eyes with numerous tiny lenses attached together enabling them to detect movement very well. They also have three small ocelli (simple eyes) on the top of the head, which detect light levels and polarisation.^[27] Most ants have poor to mediocre eyesight and a few are completely blind. Some ants have exceptional vision, though, such as Australia's bulldog ant. Also attached to the head are two antennae ("feelers") which are special organs that detect chemicals. The antennae are used in communication, receiving signals by touch and detecting pheromones released by other ants. The antennae are also used as feelers, which can detect air movement and vibration. The head has two strong jaws, the mandibles, used to carry food, manipulate objects, construct nests, and for defence.^[26] In some species a small pocket, or infrabuccal chamber, inside the mouth holds food for passing to other ants or their developing larvae.^[28]

The mesosoma ("thorax") of the ant is where all six legs are attached. At the end of each leg is a hooked claw that helps ants climb and hang onto things. Most queens and male ants have wings; queens shed the wings after the nuptial flight leaving visible stubs, a distinguishing feature of queens. Wingless queens (ergatoids) and males can also occur.^[26]

The metasoma (the "abdomen") of the ant houses important internal organs including the reproductive organs, respiratory (tracheae) and excretory systems. Many species of ants have stingers used for subduing prey and defending their nests.^[26]

[edit] Polymorphism

In a few ants there are physical castes—workers come in a distinct range of sizes, called minor, median, and major workers. Often the larger ants will have disproportionately larger heads, and correspondingly stronger mandibles. Such individuals are sometimes called "soldier" ants because their stronger mandibles make them more effective in fighting other creatures, although they are still workers and their "duties" typically do not vary greatly from the minor or median workers. In a few species the median workers are absent, creating a sharp divide with clear physical difference between the minors and majors.^[29] In other ant species there is a continuous variation in size. The smallest and largest workers in Pheidologeton diversus show nearly a 500–fold difference on dry-weight.^[30] Workers cannot mate; however, because of the haplodiploid sex-determination system in ants, workers of a number of species are able to lay unfertilised eggs leading to fully fertile haploid males. The role of workers may change with their age and in some species, such as honeypot ants, young workers are fed until their gasters are distended, and play a role in food storage. These workers with a storage role are called repletes.^[31] This polymorphism in morphology and behaviour does not rely on a large or complex genome; an Australian bulldog ant, Myrmecia pilosula, has only a single pair of chromosomes (males have just one chromosome as they are haploid), the lowest number known for any animal.^[32]

[edit] Development

The life of an ant starts from an egg. If the egg is fertilised, the ant will be female (diploid); if not, it will be male (haploid). Ants are holometabolous, and develop by complete metamorphosis, passing through larval and pupal stages before they become adults. The larva is immobile and is fed and cared for by workers. Food is given to the larvae by trophallaxis, a process in which an ant regurgitates food held in its crop. This is also how adults distribute food, stored in the "social stomach", among themselves. The larvae grow through a series of moults and enter the pupal stage. The pupa is exarate as in most other apocritan hymenoptera, having the appendages held free.^[33] The differentiation into queens and workers (which are both female), and different castes of workers (when they exist), is determined by the nutrition that the larvae obtain. Larvae and pupae need to be kept at fairly constant temperatures to ensure proper development, and so are often moved around the various brood chambers within the colony.^[34]

A new worker spends the first few days of its adult life caring for the queen and young. After that it graduates to digging and other nest work, and then to foraging and defence of the nest. These changes are sometimes fairly abrupt and define what are called temporal castes. One theory of why this occurs is because foraging has a high death rate, so ants only participate in it when they are older and closer to death anyway.^[35][36]

Most of the commoner ant species have a system in which only the queen and breeding females have the ability to mate. Contrary to popular belief, some ant nests have multiple queens while others can exist in the absence of queens. Workers with the ability to reproduce are called "gamergates" and colonies that lack queens are then called gamergate colonies while those with queens are said to be queen-right.^[37] The winged male ants, called drones, emerge from pupae along with the breeding females (although some species, like army ants have wingless queens), and do nothing in life except eat and mate. During the short breeding period the reproductives, excluding the colony queen, are carried outside where other colonies of similar species are doing the same. Then, all the winged breeding ants take flight. Mating occurs in flight and the males die shortly afterwards. The females that survive land and seek a suitable place to begin a colony. There, they break off their own wings and begin to lay eggs, which they care for. Sperm obtained during their nuptial flight is stored and used to fertilise all future eggs produced. The first workers to hatch are weak and smaller than later workers, but they begin to serve the colony immediately. They enlarge the nest, forage for food and care for the other eggs. This is how most new colonies start. A few species that have multiple queens can start a new colony as a queen from the old nest takes a number of workers to a new site and founds a colony there.^[38]

Ant colonies can be long-lived. The queens can live for up to 30 years, and workers live from 1 to 3 years. Males, however, are more transitory, surviving only a few weeks.^[39] Thus ants are more K-selected than most insects. Ant queens are estimated to live 100 times longer than solitary insects of a similar size.^[40]

Ants survive the winter by going into a state of dormancy or inactivity. The forms of inactivity are varied and some temperate species have larvae going into diapause while in others the adults alone pass the winter in a state of reduced activity. Ants are active all year long in the tropics.^[41]

[edit] Behaviour and ecology

[edit] Communication

Ants communicate with each other through pheromones. These chemical signals are more developed in ants than in other hymenopteran groups. Like other insects, ants smell with their long, thin and mobile antennae. The paired antennae provide information about direction as well as intensity. Since ants spend their life in contact with the ground, the soil surface makes a good place to leave a pheromone trail that can be followed by other ants. In those species which forage in groups, when a forager finds food they mark a trail on the way back to the colony, and this is followed by other ants that reinforce the trail when they head back to the colony. When the food is exhausted, no new trails are marked by returning ants and the scent slowly dissipates. This behaviour helps ants adapt to changes in their environment. When an established path to a food source is blocked by a new obstacle, the foragers leave the path to explore new routes. If successful, the returning ant leaves a new trail marking the shortest route. Successful trails are followed by more ants, and each reinforces the trail with more pheromone (ants will follow the heaviest marked trails).^[42]

Ants use pheromones for more than just making trails. A crushed ant will emit an alarm pheromone which in high concentration sends nearby ants into an attack frenzy; and in lower concentration, merely attracts them. Several ant species use "propaganda pheromones" to confuse their enemies, causing them to fight amongst themselves.^[43] Pheromones are produced by a wide range of glandular structures including Dufour's glands, poison glands and glands on the hindgut, pygidium, rectum, sternum and hind tibia.^[40] Pheromones are also exchanged mixed with food and passed by trophallaxis, transferring information within the colony.^[44] Ants can detect what task group (e.g. foraging or nest maintenance) other ants belong to.^[45] In ant species with queen castes, workers begin to raise new queens in the colony when the dominant queen stops producing a specific pheromone.^[46]

Some ants also produce sounds by stridulation using the gaster segments and also using their mandibles. They may serve to communicate among colony members as well as in interactions with other species.^[47][48]

[edit] Defence

Ants attack and defend themselves by biting and in many species, by stinging, often injecting or spraying chemicals like formic acid. Bullet ants (the genus Paraponera), located in Central and South America, are considered to have the most painful sting among insects, although these are usually non-fatal. They are given the highest rating on the Schmidt Sting Pain Index. Jack jumper ants, Myrmecia pilosula, located in Australia have stings that can kill susceptible humans.^[49] A vaccine from its venom extract has however been developed.^[50] Fire ants, Solenopsis spp., are unique in having a poison sac containing piperidine alkaloids.^[51] They are also of medical significance and hypersensitive humans can be at risk.^[52]

Ants of the genus Odontomachus are equipped with mandibles called trap-jaws. This snap-jaw or catapult mechanism, is enabled by a large band of muscles that are released by a "trigger". The blow is incredibly fast, snapping together within 0.13 ms in Odontomachus bauri. This is far faster than any other predatory movement in the animal kingdom.^[53] Before the strike, the mandibles open wide and are locked in the open position. The attack is triggered by stimulation of sensory hairs at the side of the mandibles. The mandibles are also able to function as a tool for more finely adjusted tasks. Trap-jaws are also seen in the Dacetini, an example of convergent evolution.^[54]

Apart from defence against predators, ants also need to protect their colonies from disease organisms. Some ant workers' maintain the hygiene of the colony and their activities include undertaking or necrophory, the transport of dead nest-mates.^[55] Oleic acid has been identified as the compound released by dead ants that triggers undertaking behaviour in Atta mexicana.^[56]

Nests may also be protected from physical threats such as flooding by elaborate structures such as elevated chambers and entrances. Workers of Cataulacus muticus, an arboreal species that lives in plant hollows, respond to flooding by drinking water inside the nest, and excreting it outside.^[57]

[edit] Learning

Many types of animals can learn behaviours by imitation but ants may be the only group apart from mammals where interactive teaching has been observed. A knowledgeable forager of Temnothorax albipennis leads a naïve nest-mate to newly discovered food by the excruciatingly slow process of tandem running. The follower obtains knowledge through its leading tutor. Both leader and follower are acutely sensitive to the progress of their partner with the leader slowing down when the follower lags, and speeding up when the follower gets too close.^[58]

Controlled experiments with colonies of Cerapachys biroi suggest that nest roles are taken up based on their previous experience. An entire generation of identical workers was divided into two groups whose outcome in food foraging was controlled by the researchers. One group was continually rewarded with prey, while it was made certain that the other failed. As a result, members of the successful group intensified their foraging attempts while the unsuccessful group ventured out less and less. A month later, the successful foragers continued in their role while the others moved to specialise in brood care.^[59]

[edit] Nest construction

Main articles: Ant colony and Ant hill

Complex nests and galleries are built by many ants but some species are nomadic and do not build permanent structures. Various species may form subterranean nests or build them on trees. Nests can be found in the ground, under stones or logs, inside logs, hollow stems or even acorns. The materials used for construction include soil and plant matter,^[38] and ants carefully select their nest sites; Temnothorax albipennis will avoid sites with dead ants, as these may be indicators of pests or disease. They are also quick to abandon established nest sites at the first sign of these threats.^[60]

The army ants of South America and the driver ants of Africa do not build permanent nests, but instead alternate between nomadism and stages where the workers form a temporary nest (bivouac) out of their own bodies.^[61]

Weaver ant (Oecophylla spp.) workers build nests in trees by attaching leaves together, first pulling them together with bridges of workers and then inducing their larvae to produce silk as they are moved along the leaf edges. Similar forms of nest construction are seen in some species of Polyrhachis.^[62]

[edit] Food cultivation

Main article: Ant-fungus mutualism

Leafcutter ants (Atta and Acromyrmex) feed exclusively on a specially adapted fungus that grows only within their colonies. They continually collect leaves which are returned to the colony, cut into tiny pieces and placed in fungal gardens. The workers are divided into a range of sizes, each suited to different tasks. The largest ants cut stalks, smaller workers chew the leaves and the smallest tend the fungus. Leafcutter ants are sensitive enough to recognise the fungi's reaction to different plant material, apparently detecting chemical signals from the fungus. If a particular type of leaf is toxic to the fungus the colony will no longer collect it. The ants feed on special structures produced by the fungi called gongylidia. Symbiotic bacteria on the exterior surface of the ants produce antibiotics that help keep away bacteria that may be harmful to the fungi.^[63]

[edit] Navigation

Desert ants Cataglyphis fortis make use of visual landmarks in combination with other cues to navigate.^[64] In the absence of visual landmarks, the closely related Sahara desert ant (Cataglyphis bicolor) has been shown to navigate by keeping track of direction as well as distance travelled, like an internal pedometer that keeps tracks of how many steps they take in each direction, and integrate this information to find the shortest route back to their nest.^[65] Several species of ants are able to detect and use the Earth's magnetic field.^[66] Ants' compound eyes have specialised cells that detect polarised light from the Sun, which is used to determine direction.^[67][68]

[edit] Locomotion

Worker ants do not have wings and reproductive females remove theirs after their mating flights in order to begin their colonies. Therefore, unlike their wasp ancestors, most ants travel by walking. Some ants are capable of leaping. A particularly notable species is Jerdon's jumping ant, Harpegnathos saltator. Jumps are made by the synchronised action of the mid and hind pair of legs.^[69]

The more cooperative species of ants sometimes form chains to bridge gaps, whether that be over water, underground, or through spaces in vegetation. Some species also form floating rafts that help them survive floods. They may also have a role in colonisation of islands.^[70] Polyrhachis sokolova, a species of ant found in Australian mangrove swamps, can swim and lives in nests that are submerged underwater. They make use of trapped pockets of air in the submerged nests.^[71]

There are several species of gliding ant including Cephalotes atratus, this may be a common trait among most arboreal ants. Ants with this ability are able to control the direction of their descent while falling.^[72]

[edit] Cooperation and competition

Not all ants have the same kind of societies. The Australian bulldog ants are among the biggest and most basal (primitive) of ants. Each individual hunts alone, using its large eyes instead of its chemical senses to find prey. Like all ants they are social, but their social behaviour is poorly developed compared to more advanced species.^[73][74]

Some species (such as Tetramorium caespitum) attack and take over neighbouring ant colonies. Others are less expansionist but nonetheless just as aggressive; they invade colonies to steal eggs or larvae, which they either eat or raise as workers/slaves. Extreme specialists of these slave-raiding ants, such as the Amazon ants, are incapable of feeding themselves, and must rely on captured worker ants to care for them . In some cases ant colonies may have other species of ants or termites within the same nest.^[75]

Some ant species enter the colonies of others and establish themselves as social parasites; species like Strumigenys xenos are parasitic to the extent that they do not have workers but instead rely on their Strumigenys perplexa hosts.^[76][77]

Ants identify kin and nestmates through their scents, hydrocarbon-laced secretions that coats their exoskeletons. If an ant is separated from its original colony, it will eventually lose the colony scent. Any ant that enters a colony with a different scent than that of the colony will be attacked.^[78] (See also Kin selection)

[edit] Relationships with other species

Ants are associated with a wide range of species and form mutualisms with other insects, plants, and fungi. They parasitise each other. They are preyed on by many animals and even certain fungi. Because their nests are such hospitable places, many species of arthropods sneak in and integrate themselves in various ways to the ant's daily lives. These inquilines sometimes bear a close resemblance to ants. The adaptive significance of resemblance to ants, ant mimicry or myrmecomorphy, is not clear. The exact nature of mimicry varies with some cases involving Batesian mimicry, where the mimic reduces the risk of predation. Other forms show Wasmannian mimicry, a form of mimicry associated with inquilinism.^[79][80]

Aphids secrete a sweet liquid called honeydew which they exude in the process of feeding from plants. The sugars can provide a high-energy food source, which many ant species collect. In some cases the aphids secrete the honeydew specifically in response to the ants tapping them with their antennae. The ants in turn keep predators away and will move the aphids around to better feeding locations. On migrating to a new area, many colonies will take new aphids with them, to ensure that they have a supply of honeydew in the new area. Ants also tend mealybugs to harvest their honeydew. Mealybugs can become a serious pest of pineapples if ants are present to protect mealybugs from natural enemies.^[81] Myrmecophilous (ant-loving) caterpillars of the family Lycaenidae (e.g., blues, coppers, or hairstreaks) are herded by the ants, led to feeding areas in the daytime, and brought inside the ants' nest at night. The caterpillars have a gland which secretes honeydew when the ants massage them. Some caterpillars are known to produce vibrations and sounds that are sensed by the ants.^[82] Some caterpillars have evolved from being ant-loving to ant-eating and these myrmecophagous caterpillars secrete a pheromone which makes the ants think that the caterpillar is one of their own larvae. The caterpillar is then taken into the ants' nest where it feeds on the ant larvae.^[83]

Fungus-growing ants that make up the tribe Attini, including leafcutter ants, actively cultivate certain species of fungus in the Leucoagaricus or Leucocoprinus genera of the Agaricaceae family. In this ant-fungus mutualism, both species depend on each other for survival. The ant Allomerus decemarticulatus has evolved a tripartite association with their host plant Hirtella physophora (Chrysobalanaceae), and a sticky fungus which is used to trap their insect prey.^[84]

Lemon ants make devil's gardens by selectively killing surrounding plants and leaving a pure patch of lemon ant trees Duroia hirsuta.^[85] Many trees have extrafloral nectaries that provide food for ants and the ants in turn protect the plant from herbivorous insects.^[86] Some species like the bullhorn acacia, Acacia cornigera, in Central America have hollow thorns that serve to house colonies of stinging ants, Pseudomyrmex ferruginea, that defend the tree against insects, browsing mammals, and epiphytic vines. Isotopic labeling studies suggest that plants may also obtain nitrogenous nutrients from symbiotic ants.^[87] In return, the ants obtain food from protein-lipid Beltian bodies. Another example of this type of ectosymbiosis comes from the Macaranga tree which have stems adapted to house colonies of Crematogaster ants. Many tropical tree species have seeds that are dispersed by ants.^[88] Seed dispersal by ants or myrmecochory is widespread particularly in Africa and Australia.^[89] Some plants in fire-prone grassland systems are particularly dependent on ants for their survival and dispersal. Many ant-dispersed seeds have special external structures, elaiosomes, that are sought after by ants as food.^[90] A convergence, possibly a form of mimicry, is seen in the eggs of stick insects. They have an edible elaisome-like structure and are taken into the ant nest where the young hatch.^[91]

Flies in the Old World genus Bengalia (Calliphoridae) are kleptoparasites which prey on ants and often snatch prey or brood from the adult ants.^[92] Wingless and legless females of the Malaysian phorid fly Vestigipoda myrmolarvoidea live in the nests of ants of the genus Aenictus and are cared for by the ants.^[92]

A fungus, Cordyceps, infects ants, causing them to climb up plants and sink their mandibles into the plant tissue. The fungus kills and engulfs the ant and produces its fruiting body. It appears that the fungus alters the behaviour of the ant and uses the ant to help disperse its spores.^[93] Strepsipteran parasites also manipulate their ant host to climb grass stems so as to help the parasite find mates.^[94] A nematode (Myrmeconema neotropicum) that infects canopy ants Cephalotes atratus causes the gasters of workers to turn red. The parasite also alters the behaviour of the ant, causing them to carry their gasters high. The conspicuous red gasters are mistaken by birds for ripe fruits such as Hyeronima alchorneoides and eaten. The droppings of the bird are collected by other ants and fed to their young leading to the further spread of the nematode.^[95]

South American frogs in the genus Dendrobates feed primarily on ants and the toxins on their skin may be derived from the ants.^[96] Several South American antbirds follow army ants to feed on insects flushed.^[97] Birds indulge in a peculiar behaviour called anting that is as yet not fully understood. Here birds may rest on ant nests or pick and drop ants onto their wings and feathers, presumably to rid themselves of ectoparasites. Anteaters, pangolins and several marsupial species in Australia have special adaptations for living on a primary diet of ants. These adaptations include long sticky tongues to pick the ants and strong claws to break into the ant nests. Brown bears (Ursus arctos) have been found to feed on ants, with as much as 12%, 16%, and 4% of their faecal volume in spring, summer, and autumn, respectively being made up of ants.^[98]

[edit] Relationship with humans

Ants perform many ecological roles that are beneficial to humans including the suppression of pest populations and aeration of the soil. The use of weaver ants in citrus cultivation in southern China is considered as one of the oldest known applications of biological control.^[6] On the other hand, ants can become nuisances when they invade habitations or cause economic losses.

In some parts of the world large ants, especially army ants, are used as sutures by pressing the wound together and applying ants along it. The ant in defensive attitude seizes the edges in its mandibles and locks in place. The body is then cut off and the head and mandibles can remain in place, closing the wound.^[99][100]

Some ants of the family Ponerinae have toxic venom and are of medical importance. The species include Paraponera clavata (Tocandira) and Dinoponera spp. (false Tocandiras) of South America^[101] and the Myrmecia ants of Australia.^[102] In South Africa, ants are used to help harvest rooibos, Aspalathus linearis, the small seeds of which are used to make a herbal tea.^[103]

[edit] As food

Main article: Entomophagy

Ants and their larvae are eaten in different parts of the world. The eggs of two species of ants are the basis for the dish in Mexico known as "escamoles". They are considered a form of insect caviar and can sell as high as 40 USD per pound because they are seasonal and hard to find. In the Colombian department of Santander, hormigas culonas (Spanish for "fatass ants") Atta laevigata are toasted alive and eaten.^[104]

In areas of India, and throughout Burma and Siam, a paste of the green weaver ant, Oecophylla smaragdina, is served as a condiment with curry.^[105] Weaver ant eggs and larvae as well as the ants themselves may be used in a Thai salad, yum (ยำ), in a dish called yum khai mod daeng (ยำไข่มดแดง) or red ant egg salad, a dish that comes from the Issan or north-eastern region of Thailand. Saville Kent, in the Naturalist in Australia wrote "Beauty, in the case of the green ant, is more than skin-deep. Their attractive, almost sweetmeat-like translucency possibly invited the first essays at their consumption by the human species". Mashed up in water, after the manner of lemon squash, "these ants form a pleasant acid drink which is held in high favor by the natives of North Queensland, and is even appreciated by many European palates".^[106]

John Muir, in his First Summer in the Sierra notes that the Digger Indians of California ate the tickly acid gasters of the large jet-black carpenter ants. The Mexican Indians eat the replete workers, or living honey-pots, of the honey ant (Myrmecocystus).^[106]

[edit] As pests

Some ant species are considered pests,^[7] and because of the adaptive nature of ant colonies, eliminating them is nearly impossible. Pest control is a matter of controlling local populations, instead of eliminating an entire colony, most attempts at control are temporary solutions.

Typical ants that are classified as pests include pavement ants, sugar ants, Pharaoh ants, carpenter ants, Argentine ants, and red imported fire ants. Control of populations is achieved using insecticide baits, either in granule or liquid formulations. Bait is gathered by the ants as food and brought back to the nest where the poison is inadvertently spread to other members of the brood – a system that can severely reduce the numbers in a colony if used properly. Boric acid and borax are often used as insecticides that are relatively safe for humans. With the recent insurgence of the red fire ant, a tactic called broadcast baiting has been employed, by which the substance (usually a granule bait designed specifically for fire ants) is spread across a large area, such as a lawn, in order to control populations. Nests may be destroyed by tracing the ants' trails back to the nest, then pouring boiling water into it to kill the queen. This works in about 60% of the mounds and needs about 14 litres (3 gallons) per mound.^[107]

[edit] In science and technology

See also: Myrmecology, Biomimetics, and Ant colony optimisation

Myrmecologists study ants both in the laboratory and in their natural conditions using a number of tools and techniques. The complex and variable social structures have made ants ideal model organisms for testing ideas in contemporary biology. Studies on ants have provided ideas in ecology, sociobiology and means to test hypotheses based on the theories of kin selection and evolutionarily stable strategies. Ant colonies can be studied by rearing or temporarily maintaining them in formicaria, specially constructed glass framed enclosures.^[108] Individuals may be tracked for study by marking them with colours.^[109]

The successful techniques used by ant colonies have been studied in computer science and robotics to produce distributed and fault-tolerant systems for solving problems. This area of biomimetics has led to studies of ant locomotion, search engines that make use of "foraging trails", fault tolerant storage and networking algorithms.^[5]

[edit] In culture

Ants have often been used in fables and children's stories to represent industriousness and cooperative effort. They are also mentioned in religious texts.^[110][111] In the Book of Proverbs in the Bible, ants are held up as a good example for humans for their hard work and cooperation. Aesop did the same in his fable "The Grasshopper and the Ants". In parts of Africa, ants are considered to be the messengers of the gods. Ant bites are often said to have curative properties. The sting of some species of Pseudomyrmex is claimed to give fever relief.^[112] Some Native American mythology, such as the Hopi mythology, consider ants as the very first animals. Others use ant bites in initiation ceremonies as a test of endurance.^[113][114]

The Japanese word for ant, ari, is represented by an ideograph formed of the character for insect combined with the character signifying moral rectitude, propriety (giri). So the Japanese character could possibly be read as The Propriety-Insect.^[115]

Ant society has always fascinated humans and has been written about both humorously and seriously. Mark Twain wrote about ants in his A Tramp Abroad. Some modern authors have used the example of the ants to comment on the relationship between society and the individual. Examples are Robert Frost in his poem "Departmental" and T. H. White in his fantasy novel The Once and Future King. The plot in French entomologist and writer Bernard Werber's science-fiction novel Les Fourmis is divided between the worlds of ants and humans, ants and their behaviour being described using contemporary scientific knowledge. In more recent times, animated cartoons and 3D animated movies featuring ants have been produced include Antz, A Bug's Life, The Ant Bully, The Ant and the Aardvark , Atom Ant, and there is a comic book superhero called Ant-Man.

From the late 1950s through the late 1970s, ant farms were popular educational children's toys in the United States. In the early 1990s, the video game SimAnt, which simulated an ant colony, won the 1992 Codie award for "Best Simulation Program".^[116]

Ants are also quite popular as the inspiration for many science-fiction creatures, such as the Formics of Ender's Game, the Bugs of Starship Troopers, and the giant ants in the film Them!. In strategy games, ant-based species often benefit from increased production rates due to their single-minded focus, such as the Klackons in the Master of Orion series of games or the ChCht in Deadlock II. These characters are often credited with a hive mind, a common misconception about ant colonies.

[edit] Citations

[edit] General references

• Bolton, Barry (1995). A New General Catalogue of the Ants of the World. Harvard University Press. ISBN 9780674615144. 
• Borror, Donald J., Charles A. Triplehorn & Dwight M. Delong (1989). Introduction to the Study of Insects, 6th Edition. Saunders College Publishing. ISBN 0030253977. 
• Hölldobler, B. & E. O. Wilson (1998). Journey to the Ants: A Story of Scientific Exploration. Belknap Press. ISBN 0674485262. 
• Hölldobler, B. & E. O. Wilson (1990). The Ants. Harvard University Press. ISBN 0674040759. 

[edit] External links

[edit] General

• Antweb from The California Academy of Sciences
• AntBase - a taxonomic database with literature sources
• Discover Life— images, information and links
• Antnest—keeping ants

[edit] Pest management

• National Pesticide Information Center
• Ant management
• Control of House Ants, University of North Texas

[edit] Images

• Myrmecos
• BugGuide

[edit] Regional

• Ants in France
• Australian ants
• Ants in Russia