Ants

Ant is a redirect to this article. Further meanings are listed under Ant (disambiguation) .

Ants
Ross ant ( Camponotus ligniperda )
Systematics
Trunk : Arthropod (arthropoda) Class : Insects (Insecta) Order : Hymenoptera (Hymenoptera) Subordination : Waist Wasps (Apocrita) Superfamily : Vespoidea Family : Ants
Scientific name
Formicidae
Latreille , 1802

Ants (Formicidae) are a family of insects within the order of the hymenoptera . They occur with more than 13,000 described species in tropical, subtropical and temperate climates of all continents. Some species also advance into the subarctic zones of Siberia. The greatest diversity of species is found in the tropics, with around 200 species in Europe. The oldest fossil finds come from the Cretaceous and are dated to an age of 100 million years. However, the age of the group is estimated to be possibly 130 million years.

Word origin

Old High German āmeiʒa, West Germanic * ǣmaitjōn (a reconstructed form, therefore written with a preceding asterisk) is a combination of Old High German ā or West Germanic * ǣ 'ab, weg' and one from the verbal stem of Old High German meiʒan or West Germanic * mait-a- ' cut 'formed noun (cf. new high German chisel ). The preferred explanation of the word for morphological reasons is therefore 'the one consisting of sections', i.e. the animal whose body is divided into clearly visible sections, which has a parallel in the etymology of insect (from Latin īnsecāre , 'cut in'). It is less likely to be named after the 'cutting off' of parts of the plant, which is less common in the case of the species native to the Germanic area.

In addition to Old High German, the word is also attested in Old English as ǣmet (t) e, ǣmytte ; from the later language levels it is Middle High German as āmeiʒe, ambeiʒe, emeiʒe etc., Middle Low German as āmete, ēmete (nine Low German extended by the -ken suffix as Imiken, Emken, Inken and the like), Middle Dutch as amete and Middle English amete, emete u. Ä. (New English ant, dialectal emmet ) handed down. Since the word formation had already become opaque early on, in Middle High German there was a reinterpretation of amei diee as ambeiʒe 'the bite' as well as numerous variants such as ämbeʒ, onmeiʒ, ommaiʒ, aimsche, eimesse and similar, which ultimately became the ones in today's German dialects occurring variants Ameis, Amois, Amas, Ambeiße, Ämess, Emenz, Emetz (e), Emmer, (H) omeise, O (a) mo (a) s, Omes, Omse, Ometzel, Umbeißi, Wurmbasle - to name but a few to call - led.

An older Germanic word for the ant is * meuriōn or in the ablaut relation to it * maura-, which is about Old West Norse maurr, Old East Norse myr (a), Middle Low German and Middle Dutch miere, Middle English müre in New Icelandic and New Norwegian as maur, in New Danish as myre, lives on in New Swedish as myra and in New Low German and New Dutch as mier (or, according to the smell of formic acid, as Pissmier ). This root is originally related to the Latin formīca, which continues an older * mormīca .

features

Scheme of a worker ( Pachycondyla verenae )

Ants have the typical body structure of insects, which is divided into head , chest (thorax) and abdomen, with three pairs of legs and, in winged individuals, two pairs of wings. Ants live in insect states based on the division of labor , which are always divided into at least three so-called castes, namely fertile females ( queen ), fertile males and workers. This division of labor is partly reflected in considerable differences in body structure ( morphology ). Queens in particular show a different shape. In contrast to those of the other females, their ovaries are fully developed, which is why the abdomen is usually noticeably large. In contrast, the nervous system, especially the cerebral ganglion (“brain”), is less differentiated because queens specialize in reproduction. The workers in most species of ants range in size from 2 to 14 mm, while males and queens can grow to be twice as large.

As with the other waist wasps , the first abdominal segment of the ants is fused with the last thorax segment and forms a wasp waist. The shape of the abdominal stalk is unique in the ants and therefore forms the decisive characteristic: the second abdominal segment, the petiolus, or the second and third abdominal segment (postpetiolus) together (as in the case of knot ants, for example ) form a stem-like, nodular or scale-like extension, the so-called Stalk. The anatomical abdomen ( abdomen ) thus forms part of the middle section of the body (or mesosoma), the stalk and the rear section of the body. Because the last section of the body morphologically consists of only part of the abdomen, it is called a gaster to distinguish it.

The mouthparts consist of an upper lip ( labrum ), a paired upper jaw ( mandibles ), a paired lower jaw ( maxilla ) and an unpaired lower lip ( labium ). They correspond to the original chewing-biting type. The upper jaw can be used in many ways. In addition to feeding, they are also used for defense, grabbing prey, transporting food, transporting eggs, larvae, pupae and even nest mates when moving a colony and building nests.

The six legs each have two claws and an intervening adhesive device. The claws offer the best grip on rough ground, while the adhesive device allows the animal to climb up even on vertical glass panes. The front legs have a feeler plaster notch on the first leg.

Sense organs

Ant head in the scanning electron microscope

The kneeled antennae are the most important and most diverse sense organs of the ants. They are mainly used for touching, smelling and tasting. Ants can use it to perceive temperature changes, air currents and the carbon dioxide content of the air. Probably the sense of moisture can also be found on the antennae. In addition, the antennas are used to a large extent for tactile communication between the individuals. Ants usually have relatively small but well-developed complex eyes with typically a few hundred individual eyes ( around 400 for Pogonomyrmex , similar values ​​for most other genera). The number of individual eyes is usually higher in sex animals than in workers and increases allometrically with their body size. The three forehead eyes (ocelli) are present in the winged sex animals , they are absent in the workers or are inoperable (exception: some genera with a very highly developed optical sense such as Myrmecia and Harpegnathos ). Seeing colors has been demonstrated in a number of species. These species can perceive UV light but not red light. Usually there are only two differently color-sensitive visual pigments (bichromatic vision), many groups (e.g. leaf cutter ants ) are even color-blind. In addition, the ability to analyze linearly polarized light has been demonstrated, which means that the animals can determine the position of the sun even when the sky is partially covered. This ability is presumably used for orientation in the terrain (proven in the desert ant Cataglyphis ). Not much is known about the forehead eyes. They can differentiate between light and dark and also perceive ultraviolet and polarized light. However, they do not seem to have a significant impact on orientation skills. It is possible that the forehead eyes only support the abilities of the complex eyes.

internal structure

The intestinal tract has the goiter typical of social hymenoptera, an expandable extension at the end of the foregut that is connected to the midgut through a valve (valve funnel). The animals can not only take in food for their own benefit, but also store it for a short time in order to subsequently feed nestmates or larvae with it. The goiter is therefore also called the “ social stomach ” of the ants.

Ants have numerous glands . The metapleural gland is a unique characteristic of this group. It produces antibiotic substances, which enables the animals to live in the damp underground. Queens and workers always have a poison gland. Most of the time, the poison is sprayed on the victim. Some species, such as fire ants, have a venomous sting. Species of the subfamily Formicinae use formic acid for defense. As a breath poison, formic acid vapor is fatal for many small animals. Most other ants use poisons, some of which are complex protein mixtures , which have neurotoxic or histolytic effects, some of which are reinforced by histamines (such as ants of the genus Myrmecia ). Fire ants use alkaloids as poisons. In addition to poisons for attack or defense, alarm substances and attractants can also be included, through which conspecifics can be notified. Secretions from other glands serve as fodder juices to nourish the queen and the larvae, messenger substances, path markers and hormones that influence the development of the animals.

box

The typical insect state consists of individuals from different castes , almost without exception females: queens as well as workers or soldiers. Usually only one individual or a few individuals in an ant colony are fertile females ( monogyny or oligogyny), but sometimes several thousand ( polygyny ).

In addition to the workers and queens, there are also the winged males. You can watch them on their wedding flight . Males only arise to mate the young queens.

The ants with the typical queen shape, the full females ( gynomorphs ), usually shed their wings after mating and then differ externally, among other things, in their size from the normal workers. A reliable feature for recognizing a queen is the so-called "queen hump". However, there are also small dwarf queens ( microgyne ) that keep their wings in the socially parasitic species . Queens with typical worker form are the ergatomorphs . In many species of ants, there are intermorphic females, which are anatomically an intermediate form (no wings, but fully developed gonads ). All three forms can theoretically function as both a queen and a worker.

In addition, there are very many species of ants with reproductive workers who have poorly developed gonads, slightly underdeveloped egg tubes and usually no or a severely reduced seed sac ( receptaculum seminis ). For example, they are used in monogynic states when the queen dies. Since workers are not mated, however, they cannot fertilize their eggs, and these therefore come about in a unisexual ( parthenogenic ) way. Therefore only males emerge from the eggs of the workers.

Within the worker caste there can be two to three sub- castes that differ morphologically , such as small and large workers or soldiers. Soldiers (for example with the driver ants) have a greatly enlarged head with very large mandibles. The so-called honey pots of the North American honey pot ants genus Myrmecocystus , the scale ants and, to a lesser extent , the southern European species Proformica nasuta , in which animals act as food stores: their goiter fills the entire guest and is filled with honey.

Systematics

Red wood ant ( Formica rufa )

Ants belong to the insect order of the hymenoptera (Hymenoptera). Within this they stand as the family Formicidae in the superfamily Vespoidea (fold wasps), a subordination of the waist wasps (Apocrita). The ants are therefore close relatives of the real wasps (Vespinae). Alternatively, the ants are sometimes assigned to their own superfamily Formicoidea. Recent genomic studies seem to support this alternative classification.

The system of ants is not yet undisputed. Bolton distinguishes 20 recent subfamilies, to which a 21st subfamily was added in 2008 (Martialinae). However, there is currently no consensus on this division, since recent molecular biological studies suggest a smaller number of independent subfamilies. These studies suggest a subdivision into three groups: Leptanilloids (Leptanillinae), Poneroids (Agroecomyrmecinae, Amblyoponinae, Paraponerinae, Ponerinae and Proceratiinae) and Formicoids (all other subfamilies).

Subfamilies of fossil and recent ants:

(System combined according to Moreau and Ward )

Formicidae

Armaniinae †      Sphecomyrminae †      Martialinae      Leptanillinae   Poneroids    Agroecomyrmecinae      Amblyoponinae      Paraponerinae      Ponerinae      Proceratiinae      Brownimeciinae †   Formicoids    Dorylomorpha   Ecitoninae      Aenictinae      Dorylinae      Aenictogitoninae      Cerapachylinae      Leptanilloidinae      Dolichoderinae      Aneuretinae      Pseudomyrmecinae      Myrmeciinae      Ectatomminae      Heteroponerinae      Myrmicinae      Formicinae      Formiciinae †      Paleosminthurinae †

Evolution, fossil record

Ants in Baltic amber

The origin and the early development of the ants is still not fully understood. Current molecular biological studies support the assumption of a monophyletic origin, i.e. the development of the entire group from a single parent form. The oldest fossils that can be assigned to the ants come from the Middle Cretaceous Period (from the Albium ) and are around a hundred million years old. The key feature of the assignment to the ants is the metapleural gland (or, in the case of fossils: its opening or its duct), the presence of a detached petiolus and the construction of the antennae with a long shaft member (scapus) and angled ("kneeling") are also important Scourge; also the reference to eusocial way of life through the discovery of animals that can be classified as workers. The extinct family Falsiformicidae, which belongs to the Chrysidoidea and had both kneeled antennae and a petiolus , shows that individual features can lead to misleading .

Most and the oldest ant fossils from the Cretaceous period come from amber finds in France and Myanmar (Burma). These are predominantly assigned to the extinct subfamily Sphecomyrminae . Sphecomyrminae were either representatives of the parent group of modern ants or their sister group . From the Sphecomyrmine Haidomyrmodes mammuthus found in France , workers and a queen were found next to each other in the same piece of amber, which proves a eusocial way of life. The most important difference to the modern ants (the " crown group ") is the construction of the antennae with a short scapus. Fossils of about the same age from the extinct Armaniinae are far less certain in terms of classification, because they only exist as compression fossils in limestone and therefore important features (such as the metapleural glands) cannot be identified.

In the same old (often in the same) fossil deposits that the Sphecomyrminae provided, there are also fossils of ants that can be classified into modern ( recent ) subfamilies. One of the oldest is Kyromyrma neffi made of amber from New Jersey , which belongs to the recent subfamily of the Formicinae . Kyromyrma is about 92 million years old. Burmomyrma rossi and Myanmyrma gracilis from Burma (about 99 million years old) as well as Cananeuretus occidentalis from Canada probably belong to the Aneuretinae . Of this subfamily, only one species, Aneuretus simoni , has survived on the island of Sri Lanka today . Morphologically primitive recent groups such as the bulldog ants (Myrmeciinae), today only in Australia and New Caledonia , are widespread in the fossil record, but somewhat younger.

Ants have become more and more common in the fossil record from the Cretaceous until today. While they make up barely 1 percent of the finds in Cretaceous fossil deposits, in the Eocene Baltic amber it is already 5 percent (from 118 species), in the early Oligocene limestone from Florissant 20 percent and in the Miocene Dominican amber 36 percent, making them the most common animal group here represent. Many types from the Baltic and Dominican amber can be assigned to modern genera. Age estimates based on the methods of the molecular clock revealed an age of the ants of 140–168 or 115–135 million years, depending on the investigation. However, it is striking that ants are completely absent in famous and abundant fossil deposits that are more than a hundred million years old, for example in the Santana Formation in Brazil (the species Cariridris bipetiolata described there is no longer considered an ant today) or in the Lebanese Amber. There is speculation here about a development on the Ur-continent Laurasia , so that they would be missing in Gondwana sites .

Of the ant species living today, the species Martialis heureka (subfamily Martialinae) or the subfamily Leptanillinae , which were only discovered in the Brazilian jungle in 2008, appear to be the most original group.

Ants and the evolutionary theory of altruistic behavior

The workers of the ants are altruistic creatures: while they do not reproduce themselves, they “selflessly” work to ensure that the queen can pass on her genes to offspring. Darwin was aware of the dilemma for the theory of evolution : How are altruistic genes passed on if their carriers - the workers - never reproduce? His attempt to explain: Complete family associations could also benefit from the selection. In 1968, the British biologist formulated William D. Hamilton 's mathematically based and generally accepted theory of kin selection (kin selection). Due to the special reproduction of state-building insects, ant workers are 75 percent related to each other, i.e. more than would be possible with their own daughter. That is why natural selection favors those genes which induce workers to raise sisters and not daughters of their own - the basis of the altruistic social ant state.

Way of life and behavior

All known ant species are organized in states . They represent the most important group of eusocial insects. Ant colonies consist of a few dozen to several million individuals. Ant colonies are organized based on the division of labor and always have at least three so-called castes: workers, females (queen) and males . In contrast to other state-forming hymenoptera, the workers in ants are basically wingless. Only the sexually mature females and males usually have wings. For mating, winged females and males are reared in most species, which leave the parental den at the same time in large flocks. In some kin groups and species, however, only the males are winged, or reproduction takes place parthenogenetically , i. H. without male. After mating, the males die, while the females shed (or bite off) or lose their wings and found new colonies of their own or return to their parents' den, in which several queens then coexist.

Ants develop a wide variety of different ways of life, from nomadic "hunters" to "gatherers" and "cattle breeders" to species that cultivate mushrooms as a source of food: the leaf cutter ants (genera Atta and Acromyrmex ). Some species are practicing slavery, as it were, by kidnapping ant larvae of other species and later letting them work for them ( e.g. Polyergus rufescens ), or social parasitism, in which the females immigrate to existing states of another species and let them raise their offspring ( e.g. Anergates atratulus ).

Ant colonies have a lasting impact on their environment. They contribute significantly to the redeployment of the upper layers of the earth, support the breakdown of plant material, spread plant seeds or, as predators, regulate the populations of other arthropods .

Ants are not closely related with the also state-forming termites that belong to a separate order (Isoptera) and closely related to mantis (mantis) and cockroaches are.

State formation

→ Main article : Hymenoptera state

The ants are among the eusocial ( state-building ) insects. In the case of ants, there are states of hardly more than ten ( Dinoponera ) to over 20 million animals. States with only one queen can usually only live as old as the queen herself, since eggs are no longer laid after her death. Queens like those of the red wood ant ( Formica rufa ) can live up to 25 years, while workers rarely live longer than two to three years. In the case of the black garden ant ( Lasius niger ), the maximum life expectancy of the queens is estimated to be 29 years. For most species of ants that train winged queens to mate exclusively outside the nest, a colony or colony can never grow older than the founding queen. In the meantime, however, numerous species with different life cycles are known, some examples are listed in the box and types chapter below. In many species the queens are wingless and resemble workers, in some of them mating occurs within the nest. Are then new colonies by division or sprouting, i. H. Jointly established by young queens and part of the workers of the old colony, the life of the state is potentially unlimited. The degree of relationship of the workers within a colony, in the theoretical ideal case 0.75, can fall to almost any value up to almost 0.

Some ant species combine numerous queens per colony ( polygyny ) with numerous nest locations per colony, with new nests being formed by sprouting ( polydomies such as Tapinoma melanocephalum ). These species can form huge super-colonies that stretch for thousands of kilometers and comprise billions of individuals, especially when the ants are introduced as neozoa into areas where they were not previously native. The ants in the various nests are not aggressive towards one another, they can freely switch back and forth between the nests, while individuals from other colonies (including other super-colonies) are fought vigorously. In the species Linepithema humile from South America, two such super-colonies were found on the coasts of the Mediterranean and the Atlantic, one of which stretches from northern Italy to Galicia, on over 6000 kilometers of coastline. This makes it the largest colony of a multicellular living being.

Nest types

Most nests are made of small pieces of wood or plants, crumbs of earth, resin from conifers, or other natural materials. Different nest types can occur within one ant species.

Ants' nests can either be built in natural or created cavities or freely.

Nests in cavities

Earth nest

Soil nests on the Pearl Beach Fire Trail, Brisbane Water National Park

Entrance to an earth nest between the tiles of a terrace

Ant paths under a stone

The earth nest is the most common type of nest in which at least the majority of all corridors and chambers are below the surface of the earth. Earth nests are very susceptible to the weather, so that they can usually only be found in particularly protected places such as under heat-storing stones. Some species also form a crater wall around their nest.

Most earth nests - such as that of the yellow meadow ant ( Lasius flavus ) - have a small dome. Such earth nests can collect more sun rays than shallow nests.

Hill nest with scattered domes

The burrow of the red wood ant is a nest of hills with scattered domes

The hill nests with scattered domes ("anthills") offer better ventilation and, at the same time, better heat storage. These nests are mostly built around rotten tree stumps that give them support. Most species of the genus Formica live in such hills . The upper layer of plant parts protects the nest from rain and cold; the lower layers are made of earth. The corridors are laid out so that water can run off them. In such nests, which can reach a height of two meters and a diameter of five meters and are twice as deep as they are high, there are numerous floors and galleries. Such nests have to struggle with fungi due to their plant components, which is why the ants completely dig up the surface of the nest every one to two weeks. This can be observed very well if you spray some paint on it: after two weeks at the latest, it has completely disappeared and reappears in another place after four to six weeks. In winter, the upper part of the hill nests serves as frost protection, while all ants hibernate in the deeper chambers.

Wooden nest

Different species of ants use their mandibles to cut nest chambers and duct systems in rotten deadwood , not infrequently also in the heartwood of living trees that have been partially degraded by fungi and whose sapwood still has enough water and nutrient pipes to survive. The entrances are at the ends of the roots so that the nest cannot be seen from the outside of the trunk. Especially the Central European black horse ant ( Camponotus herculeanus ) gnaws pronounced nest chamber systems, so-called hanging gardens, into rotten trunks. Woodpeckers, especially the black woodpecker , can locate them acoustically there.

The smaller species, especially those of the genus Leptothorax , do not need larger territories. Rather, they use small knotholes from various larvae or live in snail shells or acorns.

Ant plants

→ Main article : Ant plant

Ant plants (myrmecophytes) are all those plants that ants use as permanent living space, for nutrition (e.g. elaiosomes ) or for reproduction.

Domatia are cavities in plants where ants nest. In return, the ants usually offer the plants protection from predators or competitors ( myrmecophylaxis ). The species of the tropical genus Tetraponera ( Pseudomyrmecinae ) and the Malaysian Cataulacus muticus ( Myrmicinae ) live in the hollow stalks of two giant bamboo species. Some ants breed aphids in the plants , such as the species of the genus Azteca , which live in hollow branches and trunks of the plants of the genus Cecropia , divided by transverse walls .

Other plants in whose cavities ants live are those of the genus Myrmecodia , or the buffalo horn acacia of the species Acacia sphaerocephala , in whose hollow thorns the ants nest.

Free nester

Free nests of the ants can be bivouac nests, silk nests or cardboard nests.

Bivouac nest

Bivouac of the driver ants

→ Main article : Bivouac nest

Free nests represent the most puristic "nest shape". They are very mobile, mostly also very temporary and consist only of the ants, often of every stage of development, and their ant guests. They are formed by wandering and driving ants (of the subfamilies Dorylinae , Aenictinae and Ecitoninae ) as well as from the ponerine genus Leptogenys .

Fire ants ( Solenopsis invicta ) form floating bivouac nests during floods . Seen up close, all the bivouac nests look chaotic.

Cardboard nest

Cardboard nests are mainly found in tropical ants, which they erect on the ground or on branches.

The glossy black wood ants ( Lasius fuliginosus ) are the only native representatives to build cardboard nests in trees. To do this, they crush small wood and earth materials and soak this kneaded cardboard substance with honeydew that has been choked out of the goiter. This building material contains up to 50 percent sugar. Then they grow the fungus Cladosporium myrmecophilum , which gives stability to the nest walls through its hyphae (filamentous cell structure typical of mushrooms). Both creatures live in symbiosis , because the fungus finds optimal food sources.

Silk nest

The silk nest of the weaver ant Oecophylla smaragdina in Kinnarsani WS, India

Weaver ants of the genus Oecophylla build their nests using the silk secretion of their larvae, with which tufts of leaves are spun together. Most of these nests are free-hanging.

Silk Nest, Malaysia

Polyrhachis dives (often incorrectly also called weaver ants) build their nests (several smaller or very large) mainly from silk, which they often attach in cavities such as tree hollows orcover or camouflagewith dead organic material ( detritus ).

Organization of the ant colony

orientation

Traces left by ants in yogurt leftovers on a spoon

In addition to their sense of touch and pheromones , ants can also use the polarization of light to orientate themselves. The ants determine their direction of travel in the interplay of the direction of the light waves, which varies with the time of day, and an internal biological clock. The desert ants Cataglyphis fortis can also determine the straight line to the starting point (entrance of the underground colony) from the distance they have traveled.

Some other species also use ultrasound to orient themselves . To do this, they send through stridulation , namely by rubbing the rear pair of legs with small hooks on the abdomen (cf. the chirping when barbecuing ), sound waves from eight kilohertz up to the ultrasonic range. These are reflected on objects, collected with Johnston's organ and evaluated. Stridulation sounds can also be created by moving a gastric segment up and down on one edge of the postpetiolus . For example, leaf cutter ants that have been buried can "call for help" and be heard and dug up by other species.

communication

The exchange of information in ants takes place largely chemically via various scents and tactile by touching with the feelers. There are secretions for every situation, for example the alarm pheromones , such as the undecane from Dufour's glands . This olfactory communication is the ants' most important means of communication.

Any necessary information can also be passed on via antenna crosses. For example, the feelers touch each other briefly or long and abruptly or slidingly. This is called tactile communication. With this method, one ant can trick another ant to signal that it is hungry and needs goiter food. Even if one ant leads another to a food source and the scent trail is not yet sufficiently intense, this type of communication is necessary. These two ants organize a so-called tandem run. By touching the guests, the guided rear ant signals its presence. If this is no longer there, the guide waits and sprays secretions until both have found each other again.

Collective intelligence

Three ants are carrying a dead gecko

If several ants transport prey to the nest together, this is not based on an agreement, i.e. on communicative intelligence. Rather, each ant tries to get its prey towards the nest for itself. If enough ants have approached to be able to carry away the prey in bulk, and if enough ants are dragged in roughly the same direction, namely on the same road towards the nest, the transport train automatically starts moving. The more intensely the road is marked by pheromones , the better the train gets.

In the case of the black garden ants, it has been proven that ants do not exclusively follow the pheromone trail ( ant route ) of the founder ant when they carry their prey towards the nest. If a passage is so narrow that there are collisions between the ants moving there and back, the ants returning home take an alternative route and create a practically parallel ant road, which solidifies through use. The reason why the returning ants evade is probably due to the fact that their sense of direction is sufficient to determine the direction to the nest even without a pheromone trail, which does not apply to the prey lying in an unknown location: this can only be found through the pheromone trail.

The ant species Cataulacus muticus provides an interesting example of collective intelligence . These ants live inside a species of bamboo. When it rains, they protect themselves from flooding by having an ant lock the entrance hole in the hollow trunk from the inside, like a cork , with its head. In addition, water that has penetrated is absorbed and excreted outside after the rain (coined term: “collective pee”).

Organization of the ant colony and stimulus control

Stimulus control is closely related to “collective intelligence”. Even if the reproductive females in the ant colony are referred to as “queens”, this does not mean that they also rule over the colony. In an ant colony there is no central authority in the sense of a monarchy . The way of life and behavior of ants is controlled by “stimuli”, which are followed if they exceed a certain stimulus threshold. Such stimuli can be emitted both by the environment and by the individuals of an ant colony themselves. A simple example of this is finding a source of food. When an ant discovers a source of food, it usually stores some of this food in its social stomach , runs back to the nest (creating a scent trail with pheromones) and distributes part of this food to its nestmates. If they find the food suitable and the people are “hungry” accordingly (if the specific stimulus exceeds a certain stimulus threshold), these ants will trace the scent trail back in the direction of the food source. The scent trail gets stronger and stronger (there are heavily frequented ant trails), and more and more workers will follow it. The food source is being exploited. If the food source is found to be unsuitable or there is sufficient food in the colony, few or no workers will follow the scent trail to the food source. This will soon no longer be noticed. The organization of an ant colony is thus characterized by interactive, stimulus-controlled majority decisions made by the collective intelligence.

State development

Anthill

A distinction is made between two fundamentally different ways of establishing a state for ant species: Either a new colony is established independently by a female sex animal (the future queen), or the young queen is already accompanied by workers when it is established. In this case a new colony is created by dividing the nest (or sprouting) from an existing one. Colony establishment by sprouting takes place exclusively on foot (since workers can never fly), the new colony can be accompanied by one or many young queens. Independent colony establishment is mostly (but not always) done individually by winged queens. Even in species with colony founding through nest division, the male sex animals are usually winged to avoid inbreeding. Even with species with independent colony foundations, in addition to the winged sex animals, wingless queens or substitute sex animals can also be present, which can only extend the life of an existing colony beyond the death of the founder.

Independent state establishment

Play media file

Ants crawl out of their burrows

The most common variant is the independent establishment of a state. It is operated by an estimated 65 percent of the species in Central Europe . In this form, a mated female looks for a suitable nesting place, lays her eggs in a small closed cavity, Claustra (from Latin claustra , `` stronghold '', in Livy `` animal accommodation ''), and lays her eggs there. The brood is fed and cared for independently by her. When establishing an independent state, a distinction is made between a claustral foundation , without feed intake, and a semiclaustral foundation, with feed intake in between outside of the Claustra.

The colony founders of most species, especially the larger ones, do not need to look for food during the breeding season. When their goiter food is used up, they break down their fat reserves and strong flight muscles, which they no longer need after the wedding flight, and are thus able to produce food secretions for the larvae. For example, queens of Lasius niger weigh 15.5 milligrams due to stored reserve substances, while newly hatched queens weigh only 4 milligrams. If that is not enough either, the queen will eat some of her eggs in order to use them again and to ensure that at least some workers can develop and thus help with the care.

In the smaller species and those with a slight difference in size between queens and workers, the young queens do not have enough body reserves. Therefore, they have to go looking for food every now and then. Because they have to expose themselves more than the larger species to the danger of their unguarded brood or themselves being eaten, only a few of the thousands swarmed out young queens succeed in founding their own state.

With the first hatched workers, who are often smaller than the later ones, the new state is gradually established. Now the queen no longer takes care of the offspring; rather, it is exclusively dedicated to laying eggs. The workers now take on all other tasks, be it brood care, foraging or nest building. Such a colony foundation can also take place jointly by several queens (called: pleometrosis ), whereby they raise the brood together. The resulting state then either remains polygynous , or the queens decide by means of struggles about the hierarchy, whereby only the dominant one remains fertile and the others become workers, if not one queen kills all the others, which subsequently results in a so-called functional monogyny .

Nest division

When the nest is shared, an individual or a group of young queens leaves the maternal colony together with a group of workers. Because of the starting advantage at the beginning, their mortality is lower. However, since there are no more dispersal flights by young queens, these species are disadvantaged in their ability to spread, for example they cannot reach islands. The colonies can either split into daughter colonies of almost the same size or, in other species, continuously split off smaller groups from the mother nest. Colony establishment through colony division occurs, for example, with all driver ants , but also with thousands of other species in almost all subfamilies. Species with the establishment of a colony by sprouting often form nests which later remain in contact with each other and sometimes form large, mutually tolerant super-colonies. Some species also combine both ways of establishing colony; in addition to the winged queens, they also produce wingless sex animals, which then establish daughter colonies by sprouting.

Some species of ants with colony establishment by sprouting from the subfamily Ponerinae have even completely given up the formation of their own queen caste. With them, some of the larger workers develop back into sex animals (in contrast to queens then called "gamergaten"). In the case of the higher ants this is no longer possible, since workers can no longer be successfully fertilized with them.

Return of the queens

Queens of the bald-backed wood ant and the great meadow ant often return to their home nest, or they fly into the nests of conspecifics and try to be "adopted" by them. If successful, they are accompanied and looked after by workers in the construction. The new queen then also begins to lay eggs. Colonies of this species often have several queens, so they are polygynous and split up when they get too big. The new queen then leaves the nest with some of the workers and establishes an "offshoot nest" (branch nest formation). In addition to the genus Formica , this behavior also occurs, for example, in the fire ant Solenopsis invicta or in Cataglyphis cursor . Instead of being adopted by conspecifics, young queens sometimes try to penetrate a nest of closely related species, kill the queen there and let the foreign ants raise their offspring (temporary social parasitism).

Social parasitic ants

When a dependent state is founded, a queen looks for workers of the same or foreign species. In the special case of the blood-red predatory ant ( Formica sanguinea ), the queen looks for an auxiliary queen, mostly with the gray-black slave ant ( Formica fusca ) or the red wood ant ( Formica rufa ). She intimidates the auxiliary queen and lays eggs in her burrow. Then the auxiliary queen takes care of both clutches. When the dependent queen's first workers have hatched, the auxiliary queen is killed and her brood enslaved, so that the queen can now be looked after by the other workers. This type of dependent statehood is called temporary social parasitism . Every now and then it happens that the parasitic queen lets her host live and thus a permanent or temporary mixed colony develops (for example with the saber ant ( Strongylognathus testaceus ) and the common turf ant ( Tetramorium caespitum )).

Another type of social parasitism, the brood parasitism , can be found in the laborless parasite ant ( Tetramorium atratulum , formerly Anergates atratulus ). It penetrates queenless nests of Tetramorium species and lays a large number of eggs there, which are "adopted" by the host ants and reared exclusively as sex animals of the parasite species.

Some species of ants are not able to eat independently or to carry out nest building activities. They invade nests of their own or of foreign species and either kill all ants living there in order to use their burrow for their own people, or leave only the soon-hatching larvae intact in order to raise them as slaves. Most of the time, raids are undertaken in this form in order to constantly get new slaves. Slaves attitude is found in the Amazon ant ( Polyergus rufescens ) and the blood Red robbery ant Formica sanguinea (slave species of the subgenus Serviformica ) in sublaevis Harpagoxenus (slave species of the genus Leptothorax ), or the genus Temnothorax (former genus Chalepoxenus and Myrmoxenus ; slave species from the Genus Temnothorax ), as well as the genus Strongylognathus (slave species from the genus Tetramorium ).

nutrition

Harvest ant in the scanning electron microscope

Leaf cutter ants from Colombia

Meat ants overwhelm cicada

The original diet of ants is also the one as a robber, in the jargon predator called. The predation of other arthropod species is particularly important . Very many species of ants have developed as a supplementary or alternative food source high-sugar plant juices, which they harvest directly, for example from extra-floral nectaries , but more often from sugar-rich excretions from the order of the Schnabelkerfe , called honeydew . Some species of ants have specialized in nutrition based on seeds , which differ from other plant tissues in that they have a high protein and fat content and are therefore more similar to animal tissue. Actually herbivorous ( phytophagous ) species that would use green leaves, for example, do not exist - with the exception of the leaf cutter ants , which do not use the plants themselves, but grow fungi on them. Determining the actual diet of ant colonies in the wild is extremely difficult because many species use numerous food sources, but many of them only in very small quantities or opportunistically, depending on the availability. The most important technique for the investigation of such omnivorous , in technical terminology omnivorous, species is the isotope investigation of stable isotopes, in particular δ13C and δ15N .

Omnivores

True omnivory is rather rare in ants. Well-known examples are the red fire ant Solenopsis invicta or the pharaoh ant Monomorium pharaonis as well as some other species classified as pests . In the wild, Central European species, a combination of hunting diet with the use of honeydew (with the opportunistic use of other food sources to a small extent) is particularly widespread. In this sense, the best known native ant species, the red wood ant , is also an omnivore . Their diet consists mainly of insects (e.g. caterpillars , butterflies , flies ) and other invertebrates (e.g. spiders ). In addition, excretions from various plant sap teats ( honeydew ) are used. In a closely related species ( Formica aquilonia ) in Finland, for example, the diet of honeydew made up about 80 to 90 percent of the total amount of energy, almost all of the rest was predatory insects and other arthropods. In Central Europe, according to older studies on Formica rufa , the following was stated: honeydew 62 percent (mainly from root-sucking species), insects 33 percent, tree sap 4.5 percent, animal corpses and fungal fruit bodies 0.3 percent, seeds 0.2 percent.

Predators and scavengers

A number of species of ants - for example driver ants - feed exclusively in a predatory manner. In addition, some species also feed on fresh carrion . Some species of ants specialize in certain prey animals. The South American knot ant genus Dacetone feeds exclusively on springtails .

Ant species that live nomadically, such as the driver, wandering and amazon ants, hunt as a whole colony . The wandering ants , for example, form fronts that can often be 14 to 20 meters wide. In addition to various invertebrates, they also occasionally prey on nestlings , small mammals and snakes .

Use of plant-sucking insects

"Milking" ant

Many species of ants live in symbiosis with plant sap-sucking insects ( called trophobiosis , since ants provide protection against food) and thus in mutual dependency. The trophobionts are myrmekophil , the ants mostly aphidophil , i. H. their symbiotic partners are predominantly phloem absorbent scale insects (Coccoidea), aphids (Aphidoidea) and psyllids (Psylloidea). Phloem is high in carbohydrates but very little protein . Phloem suckers therefore only consume about ten percent of the carbohydrates; the excess is excreted as sugar-rich honeydew - the ants' most important source of carbohydrates. The ants “milk” the leaf suckers and in return guard them from predators. Some species of ants let the aphids overwinter in their nest or carry their eggs into their nest to protect them from the cold. Larvae washed away by the rain are searched for and brought back by the ants.

Some ants look specifically for leaf suckers and move them to plants preferred by the plant suckers. If a herd becomes too large, the ants drive or carry the lice or their eggs to a new plant. Wars have been observed between different ant states, in which they fought for supremacy over herds of lice.

See also:

Ants cultivate aphids ( Wikimedia Commons )

Seed eater

The granivorous harvest ant species of the genus Pogonomyrmex that occur in the semi-deserts and steppes or the genus Messor , which is widespread in warmer regions of Europe and Africa, collect mainly grass (for example cereal), but also other plant seeds, which they store en masse and from which they themselves feed exclusively. Among the harvest ants, there are workers with enlarged mandibles (so-called majors) who only crack the seeds that are dragged along the up to 200-meter-long ant trails. Less specialized harvest ants such as representatives of the pheidole or tetramorium are not only dependent on plant seeds and also use other food options.

Seed collector

This group includes the elaiosome- eating ants, e.g. B. most wood ants and garden ants . The elaiosome is a food body rich in protein and fat, which is found as an appendage to the seeds of herbaceous plants that grow close to the ground (such as various types of violet and lark spur ). The seeds spread on these plants by ants ( myrmecochory ). The mostly very small seeds are transported away as a whole and therefore distributed, but only the elaiosome is used.

thieves

Thieves or casual thieves build passages in foreign nests or even brood chambers and kidnap the foreign brood in order to consume them later. This kleptoparasitism has been observed, for example, in the pharaoh ant ( Monomorium pharaonis ) and the yellow thief ant ( Solenopsis fugax ), which were introduced into Europe and have to be registered in several countries .

Mushroom grower

Some species of ants in the Attini tribe grow mushrooms. These include the South American leaf cutter ants of the genera Atta and Acromyrmex , which grow a mold-like fungus ( Attamyces bromatificus ) in their nests up to eight meters deep and slightly elevated above ground and live with this and a bacterium in a rare triple symbiosis.

The ants bring in leaf and plant parts, chew them into a pulpy, largely fungicide- free mass, which then serves as a special breeding ground for the fungi. In return, the fungi form protein-rich thickenings (gongylidia or bromate ) at the ends of the fungal threads , which serve as a source of protein for the ants. The fungi also break down the cellulose in the plant materials in such a way that they can be used by the ants, and they also break down insecticides . The third in the triple symbiosis are bacteria of the genus Streptomyces , which have their habitat on the underside of the ants and produce antibacterial and fungicidal substances. So that the ants protect their mushrooms before highly specialized parasites such as the filamentous fungi belonging Escovopsis species, which threaten the harvest of ants. Some Attini species grow mushrooms on caterpillar droppings or other organic materials.

Reproduction

Egg laying

After the winter rigor, the queen warms up for three to eight days and then begins to lay eggs (several hundred a day, up to 300 eggs for the red wood ant). In most species it is first and foremost the eggs of sex animals (males or young queens), as queens hatched late have little chance of founding a new state and thus preserving the species.

Like all colonizing hymenoptera (Hymenoptera), ants do not have sex chromosomes. The queen can decide whether an egg should become a female or a male, depending on whether or not she sprays the egg in her fallopian tubes with the sperm syringe. It is still unclear how the Queen will make this decision.

Sometimes there are also queen eggs (using the example of the small wood ant). They are much greater because they at the rear end of the egg a special RNA - protein foods contain the Polplasma, that the embryo need to develop into queens.

Some species of ants (such as the weaver ants of the genus Oecophylla ) lay trophic eggs. These eggs are not laid to produce offspring, but serve as feeding eggs that the larvae are later fed with.

Egg care

Ant eggs are mostly soft-shelled, elongated ellipsoids up to a millimeter in length. After the eggs are laid, the brood carers use their mandibles to carry the eggs into the incubation chambers, where the appropriate temperature and humidity prevail. If this microclimate changes due to external influences (e.g. destruction), the eggs are immediately transported by the workers to other incubation chambers.

The brood carers lick and saliva the eggs again and again in order to keep them clean and to protect them from drying out. The eggs also stick to each other and can be transported as “packages” if necessary.

In some species, the workers eat part of the unfertilized eggs if too many males would otherwise arise.

The development of the eggs in ants takes between one and four weeks, depending on the species, and around two weeks in the red wood ant.

Larval stage

cocoon

After a while, the white or yellowish, maggot-shaped larvae hatch from the eggs. With the exception of the head capsule, they are soft-skinned, usually slightly hairy and more or less mobile depending on the species. They are legless, and eyes are not formed either. Brood keepers transport the larvae of some species into the sun, feed them through their crop and clean them so that they do not dry out or grow fungus. The brood keepers feed the larvae using "goiter-to-mouth" feeding, known as trophallaxis . Since imaginal ants can only consume liquid or very finely chopped food due to the structure of their goiter, the opposite way also plays a role: Workers feed the larvae with food particles that are indigestible for themselves and later, especially in times of lack of food, are trophallaxis, co-fed by them (referred to as "social goiter" or "social stomach").

In most ant species, the nutrition of the hatched larvae and their position in relation to the queen are important for the formation of sex animals. Only larvae that are very well fed can develop into queens. All eggs (including queen eggs) that are very close to the queen usually develop into workers. This can be explained by the pheromones given by the queen . The definition of sub-boxes for workers (small and large workers or soldiers) is also mostly based on food. The males also receive a special diet. While earlier investigators classified an additional genetic basis of the caste determination as uncertain, today there are serious indications of this in numerous species.

As is typical for all waist wasps , the larvae collect the indigestible food residues in the so-called excrement sack, which is located at the end of the midgut. Only at the end of the larval period is the connection to the anus fully established, so that the contents of the feces bag can be disposed of as so-called meconium when it is transformed into a pupa . In such ants, whose pupae lie in cocoons , the larval droppings are visible through a black point on the caudal pole of the pupal shell as soon as a connection has been established between the intestine and stomach.

As with all holometabolic insects, the entire growth of the ants is limited to the molting processes and thus to the larval stage. The larvae usually develop quickly: the larvae of the red wood ant can pupate within eight days.

Type-determining factors

Which caste or gender an individual will belong to is decided by differences in individual development ( ontogenesis ), even if in rare cases, as in Harpagoxenus sublaevis, genetic factors can play a certain role. In general, eggs with a single ( haploid ) chromosome set result in males, while eggs with a double ( diploid ) chromosome set result in females.

Whether a female becomes a (fertile) queen or a (sterile) worker and to what extent further differentiations occur within the working class, depends on numerous factors that influence the larval development. Hölldobler names the following factors that affect the development of every individual ( differentiation ):

• Diet: amount and quality of food, possibly special food secretions from the fodder glands
• Temperature: frost, optimal development temperature
• Humidity
• Day length
• Caste self-inhibition: Individuals of a caste prevent the emergence of further individuals of the same caste (often occurs in queens)
• Egg size and yolk content
• Age of the queen

Often times, the development of the individual is influenced by a combination of these factors. In Myrmica ruginodis , for example, only larvae that have been exposed to the winter cold can grow into queens at all. However, they must be sufficiently nourished that they are at least 3.5 mg in weight about eight days after hibernation. Lighter larvae and those that are not exposed to the winter cold develop into workers.

Pupal stage

Ant pupae

In the pupal stage, the ant takes no more food and remains completely motionless. Before pupating, the larvae of most scale ants and primeval ants spin themselves into a dry shell ( cocoon ) by means of a spinning gland secretion emerging from their labial glands . The larvae of the knot ants, however, pupate without a cocoon.

The pupal rest lasts around 14 days in the red wood ants, but significantly longer in many species. The pupal cocoons are transported and cared for by the brood carers to the most favorable locations. They also help with hatching and feeding and clean the young ant for a few days until its chitin shell has hardened and darkened.

Wedding flight

Winged sex animals of an ant species before the start of the wedding flight

Once the young queens and males have hatched (in the case of the native species at the beginning of May), the entire state prepares for the wedding flight . The winged sex animals increasingly feel the urge to climb high points such as blades of grass, hills or trees. Workers take care that the sex animals do not move too far from the nest and bring them back into the burrow if necessary.

At a species-specific point in time, which presumably depends on certain air currents, light conditions and temperatures, all sex animals of a species swarm out of the different colonies at the same time for their wedding flight. Native species usually swarm in early or midsummer. Especially tropical and subtropical species swarm twice a year. The joint, synchronized swarming makes contact between sex animals from different nests, and thus cross-fertilization, easier.

In many species of ants, the young queens sit on the ground; they attract male sex animals through pheromones . With some, such as the driver ants, the males invade another colony or burrow, the queens never leave the mother colony. In other species, the males form wedding flocks into which the young queens fly, copulation takes place with them while they are still in flight or under the flock on the ground. Each young queen can be mated by several, two to 40 males. It takes in up to several hundred million sperm in its semen sac, which it can store undamaged for an average of 25 years and with which it fertilizes the eggs.

The males die a few hours after the wedding flight, they are then regarded as food by the workers and taken into the burrow. After mating, the queens break off their wings with their middle and hind legs.

Interaction with other living things

Predators

Some ant lion species catch ants with the help of funnels, which they hollow in sandy soil

In Central Europe, some bird species such as B. the green , great spotted and black woodpecker , small snakes , amphibians , spiders , insects , but also wild boars of ants. The larvae of the ant maids , the ant lions , are among other things specialized in capturing ants. The green woodpecker covers half of its daily food requirements with around 3000 to 5000 ants.

Outside of Europe, anteaters are especially important predators, in the south of the USA and in Central America the toad lizards ( phrynosoma ) are of greater importance, as they feed almost exclusively on ants.

Many invertebrates (such as predatory bugs ) imitate the ants' pheromones and use them to lay ant trails on which the ants run towards their enemies. Some arachnids, species of millipedes, and beetles specifically mimic the pheromones found in ant larvae. In this way, they can enter the burrow to the brood chambers unhindered, sometimes also carried by the brood keepers, and use the larvae. Both forms can be counted as chemical mimicry .

Ant guests

→ Main article : Ant guest

Ant guests are animals that live in ant burrows. This includes mainly insects , but also spiders . Forms of coexistence are Synechthrie or Syllestium, Synökie , Symphylie and parasitism .

In the predatory form of coexistence - synechthria or syllestium - the ant guest feeds on ants, ant larvae or ant eggs. Various strategies are used: Ant spiders mimic ants in shape and behavior, while some blue caterpillars , for example, protect themselves against attacks by ants with a thick protective coat.

Synökie means a coexistence of different species without any particular mutual influence. Various springtail species , the larvae of the Hoverfly genus Microdon , the leaf beetle genus Clytra , wingless crickets of the genus Myrmecophila (e.g. the ant cricket ), antfish ( Atelura spp. ) And the rophies of the genus Dinarda live on the food supplies of the ants. Outside the breeding areas in anthills are often found Rose beetle larvae .

With the symphyly , the ant guests are protected and often fed. For example, the ants receive nutritious glandular secretions. Such guests include the raven beetles of the genera Lomechusa and Atemeles , club beetles of the genus Claviger and some blue caterpillars.

Ants can fall victim to parasites , such as mites that suck up their hemolymph . There are also mites of the genus Antennophorus : They live on the ants and, through irritation, induce the ants to release drops of food on which the mites feed. Mites of the species Laelops oophilus live with the larvae and are fed by the brooders .

The internal parasites include the larvae of some parasitic wasps and various roundworms . Ants also serve as a second intermediate host for the little liver fluke .

Other internal parasites are the fungi ants core club ( Ophiocordyceps myrmecophila ), see core clubs , and O. unilateralis .

75 percent of the worldwide occurring butterflies from the family of the bluebells (Lycaenidae) live in their caterpillar stage myrmekophil , i.e. of or with ants. Thereby symbiosis and parasitism occur with all intermediate stages. Some caterpillars , such as the silver-green bluer ( Polyommatus coridon ) or the cranesbill bluer ( Plebejus eumedon ), serve the ants as sources of honeydew, similar to the plant lice. For this they are protected from predators. Other blue caterpillars live parasitically or symbiotically as ant guests in the ant burrow. So the caterpillar of the will gentian Blue butterfly ( Phengaris alcon ) of forest node ants ( Myrmica ruginodis adopted) and fed without compensation as an ant larva. The caterpillar of the Dark Burnet Blue butterfly ( Phengaris nausithous ) is from the Red Garden Ant ( Myrmica rubra also like the own brood maintained), but gives sugar water on the ants from. In addition, the caterpillar eats the brood of ants.

Some bluebirds are totally dependent on a specific species of ants. The common blue ant ( Phengaris arion ) needs knot ants of the species Myrmica sabuleti to develop. Against the secretion of a sugary secretion, the caterpillar is allowed to feed on ant larvae. A decline in the ants due to changes in the livestock industry in the British Isles (the ants prefer short, i.e. grazed, grass) led to the extinction of the bluer there.

Ant and human

Economical meaning

Roasted ants from Colombia

Occasionally, ants are used as food. The Mexican dish Escamoles z. B. consists of the larvae and pupae of two species of ants.

See also : insects as food

The harvester ants of the species Pogonomyrmex barbatus that one as wood pests considered to promote forestry by accelerating the degradation and conversion of wood that is infested already from other insects. The predatory driver ants or wandering ants probably make further significant contributions to forestry in tropical and subtropical areas. They are effective in eliminating other, even more harmful, insects and therefore are not always unwelcome in human living and commercial areas.

While the many seed-collecting ants can be detrimental to agriculture when they become too numerous in the vicinity of cornfields and granaries, their presence can normally encourage production by counteracting the increase in harmful parasitic beetles.

The pupae of certain species of forest ants were coveted commodities in parts of Austria , Bavaria and Bohemia for centuries. Ants , who established their own trade in Lower Austria up to around the middle of the 19th century, collected and dried the dolls and sold them on the market as bird food . In addition, folk medicine ascribed a healing effect on rheumatism to the animals .

Impairments to humans

Stings from ants of the genus Tetramorium

The red fire ants were introduced to Australia in the early 1950s. Under the very favorable environmental conditions of the Australian outback, they have multiplied strongly, u. a. also near cities. In fact, they see people as intruders into their territory and try to defend themselves. In some people, their bites and the poison from their sting cause allergies, like bee or wasp stings.

Aphid ants are common pests in gardens. In addition, anthills in ornamental lawns and ant trails in and near residential and farm buildings are often perceived as annoying.

See also : Ant Control

attitude

Native or exotic species of ants can be kept in special, prefabricated containers, the so-called formicariums . Ant keeping has now become a popular hobby; it belongs to the field of knowledge of terraristics . The necessary purchases depend on the requirements of the respective species. For example, the effort for the leaf cutter ants Atta cephalotes is unusually high, as they constantly need fresh leaves to grow their food (a mushroom). Native species, such as the black garden ant ( Lasius niger ), on the other hand, can also be kept in a simple plaster nest with an attached arena (sandy soil).

For European species, it is important to observe the hibernation period from mid-October to April, which should either be kept in suitable containers in the refrigerator or protected from frost on the balcony or in the garden. Without this hibernation there is a weakening of the ant colony, which can lead to the death of the colony.

The increasing popularity of ant keeping in recent years can also endanger natural ant populations. Searching for and digging up free-living queens for keeping or breeding usually means that the colony will die off. This is not only the case when the queen is removed, but also when the search has largely destroyed the nest and thus becomes susceptible to external influences and enemies. Since it is usually very difficult to make out the queen, many nests are often damaged. Another threat is the release of colonies in non-native locations. While exotic species usually die in winter, species from similar climatic regions can establish themselves every now and then and then form a direct danger, for example through competition, or indirect danger, for example through the introduction of parasites, for other ants or other species. Even releasing native species is not easy. If this happens too much, it leads to an alignment of the genetic information over a larger area and thus reduces biodiversity.

See also : “Notes on keeping exotic species of ants” in the article: Formicarium

Popular claims, legends and records about ants

Supposedly extraordinary physical strength

Information board of the state forest administration with incorrect extrapolation in the bison reserve near Waren (Müritz)

Popular literature repeatedly claims that ants have a special ability to carry hundreds of times their own body weight. Other insects are also assigned incredible abilities and physical strength in similar “calculations” - measured against the dimensions of humans. The extrapolation that a person with a body mass of 50 kg would have to be able to carry a package with a mass of five tons is a sleight of hand. It is not taken into account here that the weight and the mass increase with the third power of a length, while the cross section of a muscle, which is exclusively decisive for the force, only increases by the square of the length. If you linearly enlarge an ant 10 mm in length to 200 times its length, then with a length of 2 m you would get the size of a human. The mass and thus the weight would increase eight million times (200³ = 8,000,000) from perhaps 10 mg to 80 kg. But then the muscle strength (with the same body proportions) only increased forty thousand times (200 · 200 = 40,000). If an ant can carry 100 times its body weight (mass 100 · 10 mg = 1 g), then it should be able to carry 40 kg in human size with the same proportions. So it is a completely normal achievement in biology.

Records and the extraordinary

The largest ant colony found is in southern Europe and is formed by the Argentine ant Linepithema humile . It extends along the Italian Riviera to the north-west of Spain over a length of 5760 kilometers. The colony consists of several million nests with several billion individuals. Research has shown that ants from this colony and those from larger colonies of the same species on the coast of California and the west coast of Japan do not fight each other, which leads to the conclusion that the range of said colony may now extend over several continents, spread by humans. That would make it the largest known spread of an insect colony.

The measurement of a nest of leaf cutter ants showed a depth of eight meters below the ground and a total area of ​​50 m².

An ant colony can create 1900 chambers within six years. To do this, around 40 tons of earth have to be brought into the chambers and 6 tons of pieces of leaf.

A Siberian ant species overwinters in a kind of rigid cold at temperatures below −40 ° C.

Weaver ants can hold on to smooth surfaces so tightly that it takes almost 200 times their body weight to loosen them.

Desert ants ( Cataglyphis bombycina ) are among the fastest insects among the ants with a speed of around one meter per second.

One of the remarkable anatomical skills that some species of ants have developed is the snap- jaw ant's jaw closure , which can occur so quickly that it can catapult itself away from predators.

literature

• Wilhelm Goetsch: The states of the ants. 2nd edition Berlin / Göttingen / Heidelberg 1953 (= Understandable Science , 33).
• Bert Hölldobler , Edward O. Wilson : Ants. The discovery of a fascinating world . Birkhäuser, Basel / Boston / Berlin 1995, ISBN 3-7643-5152-7 .
• Bert Hölldobler, Edward O. Wilson: The superorganism. The success of ants, bees, wasps and termites . Springer Verlag, Berlin 2010, ISBN 978-3-540-93766-1 .
• Bert Hölldobler, Edward O. Wilson: In the footsteps of the ants. Springer Spectrum, 2013, ISBN 978-3-642-32565-6 .
• Wolfgang Schwenke: Ants: the scent-guided state (LB nature library). 2nd Edition. Landbuch Verlag, Hannover 1996, ISBN 3-7842-0309-4 .
• Bernhard Seifert : The ants of Central and Northern Europe . Lutra, Görlitz / Tauer 2007, ISBN 978-3-936412-03-1 .
• The ants as skeletons . In: The Gazebo . Issue 26, 1853, pp. 283 ( full text [ Wikisource ]).

Web links

Commons : ants  - collection of images, videos and audio files

Wiktionary: Ant  - explanations of meanings, word origins, synonyms, translations

Wikiquote: Ant  Quotes

• www.ameisenwiki.de - interesting facts about ants and their keeping
• www.ameisenschutzwarte.de - Internet presence of the Deutsche Ameisenschutzwarte e. V.
• antbase.net - Ant database project of the German Research Foundation
• antbase.org - lists approx.12,500 species of ants (English)
• antweb.org - database of ant genera and species around the world
• Extensive collection of 2,600 ant books and specialist articles for free download at archive.org (including approx. 160 German-language titles ).
• Ants in Xinjiang (PDF; 324 kB) collected by David Hummel during the Sino-Swedish expedition 1927–1930
• Ants (PDF; 114 kB) - UmweltWissen, Bavarian State Office for the Environment
• Ants Down Under - overview of the ants of Australia

Individual evidence

1. ↑ AntCat
2. ↑ D. Agosti, D. Grimaldi, JM Carpenter: Oldest known ant fossiles discovered. In: Nature , Volume 391, January 29, 1998, pp. 447 ff., Doi: 10.1038 / 35051 (English).
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