The hard-working ant
The term commonly used ant corresponds to the large family of insects within Hymenoptera Formicidae. Ants constitute 10% of animal biomass, and about 50% of that of all insects. The ants are especially common in tropical climates such as eastern Australia, Africa and the ' South America and Asia are scarce in North America and Europe. Ants are eusocial insects, as well as all isotteri and many other hymenoptera. In their society, which vary in size and organization depending on the species, there is a reproductive class - consisting of the queens (fertile females) and males - and the workers are wingless, sterile females, called "workers".
The ants have appeared on earth between 140 and 168 million years ago, simultaneously with the angiosperms, evolving from solitary wasps So far, the oldest fossil found evidence of the existence in the late Cretaceous, a species with many physical characteristics vespoidali (compound eyes large, flexible stalks reduced and abdomen), which was christened Sphecomyerma Frej. So far we know about 5 subfamilies extinct. The oldest still existing species belong to the genera and Amblyopone Proceratium, although the more primitive species, preserving a social structure typical of the species first appeared, both Prionomyrmex macropsia.
There are at least 12,000 species of ants that are classified into about 300 genera and 21 subfamilies. Like other insects, ants have a body divided into head, thorax and abdomen. They have six legs, chewing mouth with strong jaws and elbowed antennae. Between the chest and abdomen to tighten ants derived from structural modification of the first two uriti of gastro, nodular or squamiform, which are called post-petiole and petiole. The most typical color is black ants, but there are many ranging from red to orange to yellow and green. The antennas consist of a basal part, established by the scape and pedicel, and a flexible cord that consists of a series of segments whose number varies depending on the species.
The worker ants range in size from 1 to about 30 mm of Camponotus gigas, normally fertile females (called queens) are larger than the sterile workers and in some species can reach 6 cm.
The workers have a big head and strong jaws strong, but less developed than those of the soldiers, small eyes, antennas formed by eleven or twelve segments or less. After the two abdominal segments of the stalk, the abdomen swells to a climax and sometimes takes the sting working, while in other cases it is atrophied (formicinae, dolichoderinae). The workers and soldiers differ because the latter have a much larger head. The fertilized female is larger, has the ocelli and wings but drop after mating. Males are generally small, always with wings and have highly developed eyes and ocelli, their chest is bigger, while the three pairs of legs, are common to all insects, are small. In almost every case, the workers have no ocelli, although queens and males are often fitted. The digestive system of ants consists of two expansions bag, called craw and gizzard. In the first lot are accumulated food substances, of which only a small fraction passes into the gizzard and is digested and assimilated by the individual.
The rest of the food nell'ingluvie content is regurgitated and given as food to other parts of society. Among the organs, is the most developed sense of smell which has its headquarters in the antennae and the ants need to feel the sensations most popular and useful life. The eyes do not give very specific feelings. At the base of the mandibles flow into the pipes of special glands located in the head and secreting a substance that, when mixed with chopped wood, cardboard form used by some species to build nests. In the last portion of the abdomen, which flow into the poison glands of formic acid and other toxic or irritating, or, in other species, special anal glands secrete a substance containing odoriferous butyric acid, "iridomirmecina" and some other substances and foul smelling which are sketched out for defense or offense.
In some species the stalk and the top of the abdomen, the organs are placed stridulanti which, through friction, emit weak sound.
In ants, the reproductive system is developed in all individuals, even if, in the working class, has atrophied and does not allow sexual reproduction. Ants, like other eusocial Hymenoptera are characterized by a particular mechanism of sex determination, haplodiploid said. Females develop from fertilized eggs, called anfigoniche, while males are born from unfertilized eggs, which are known as parthenogenetic. To adjust the fertilization of eggs, the queen uses a special bag at the back of the abdomen, called the spermatheca.
The eggs of the ants have no protective wrappings. The larvae are triangular, often with no limbs and unable to carry out complex movements, but can shrink if threatened. The workers eat the larvae in their mouths regurgitating small drops of food through trofallassi, or providing them with trophic eggs. In some species the larvae, equipped with jaws, they are able to break the membrane of the eggs alone, while others are the same workers who break the eggs and trophic offer directly to the larvae. From the body and, in some species, by special papillae around the mouth of the larvae, and special liquids oozing grease like that much to the workers and that they eagerly lick.The larva of the ant secretes a bit 'silk, which, when mature, it weaves a cocoon where he spent the pupae. This cocoon, to develop, should generally be buried by the workers. The eggs, larvae and nymphs are cared for with great care by the workers, who deliver in the most comfortable in the nest according to the needs of their development. The care of children is the most work takes place in the nest. The queen does not work and live from fifteen to twenty. The workers live five to ten years, males, however, die after having mated. Ants live in societies that can be formed from a few tens or hundreds of thousands of units, up to a few million, but only in exceptional cases, that is, a territory inhabited by large animals with thick vegetation.
Reproduction of workers
The workers have atrophied reproductive organs, but they can lay parthenogenetic eggs, known as "trophic." The eggs of the workers are generally offered to the larvae as food. In some species in extreme cases, the workers leave the nest and form new colonies by laying trophic eggs, which develop by parthenogenesis telitoca in females. In other species), a company formed exclusively of workers, which reproduce by parthenogenesis telitoca. In many species of ponerine ants, such as Harpegnathos venatior, the workers, which in this case are called gamergati can also reproduce anfigonicamente.
The ants are, together with bees, the most notable among the social insects. Their organization is well known and very efficient. The structure of the colonies and their social organization may vary from species to species.
Ants are insects 'social' in the sense that they live together in society where everyone works according to the welfare of the community. The vastness of the family and the diversity of costumes of the numerous species mean that no other group of social insects have as much variety of life patterns and social forms. The ants are omnivorous, carnivorous or frugivorous. The structure of the "nest" (ant), varies considerably in relation to the material and found that the climate of a given environment. Consequently, even their social organization varies greatly from group to group, and so are their habits, in a sense, more diverse and interesting than those of bees and wasps. Colonies of ants act as reproductive units of the species.
In some species of primitive ants, for example Dinoponera and Paraponera, the colonies are composed exclusively of females that produce other females through parthenogenesis telitoca, which is a form of sexual reproduction is very common among insects in general, but very rare in the rest of the family Formicidae. The social organization of these colonies is based on a hierarchy, where the last "step" is home to those older women who gained the ability to reproduce after a series of conflicts with other airline. The eggs laid by females are eaten by the dominant subject.
In the vast majority of ant species, the female is polymorphic and is divided into morphological castes. The social organization of the colonies depends on females of this subdivision. The castes are divided into gendered and sterile individuals are known as sterile workers are defined as those sexed queens. The job functions are performed primarily by the workers, while the reproductive queens are undertaken. In some species the workers can also take on reproductive functions. In many species of ants you have a polymorphism between the workers, that there are more of a caste of sterile females.In many species of ants, colonies are founded by single queens, who, after being paired with males, they alight on the ground, dig a hole in the ground - this will become the nest of the new colony - and detaching the wings. The males die when coupled. During the period between the first deposition of eggs and development of the first adult, the queen does not eat: it survives thanks to the fragments of the wing muscles enter into his circulatory system. In some ant species, queens are permanently wingless, and the foundation of new colonies occurs with the help of workers. In some species a single queen colonies include ovideponitrice, in others a group of these, usually descendants of a single mother.
Ants are territorial and very aggressive insects. In the colonies of Myrmecia, the workers use to kill each other for dominance of the territory controlled by its own colony. The ants also make wars between colonies or different species. In fact, they are among the few animals that, like humans, are at war with each other. The ants of a colony will identify themselves by smell, and kill any animal of the neighboring colonies to eliminate competition in the food-gathering or in the domain of the territory.
In some species, insects, plant pests such as aphids, coccidia (or scale insects), are raised by the workers, protected and distributed on the plants. From these ants derive a sugary substance - honeydew - urging the insect antennae.
The nests, these ants can be very simple or incredibly complex. Ants are mostly insects living in the soil, however, there are forms that live in the trunks of trees or on leaves.
As a rule, an ant-hill is formed by a complex of rooms, located on several floors of corridors and communicating through these tunnels. In each room, many individuals live together and there are also rooms designed to contain only the eggs, or only the larvae or nymphs only, which are moved to places where the humidity and temperature are particularly suited to development. The nest may be entirely underground and communicating with the surface through a single opening, or may variously rise above the ground and have one or more ports. These are constantly monitored by one or more ants, which act as sentinel. The doors are sometimes represented by stones or other small solid fragments, and are closed in case of danger, on cloudy days or during thunderstorms.
Special devices prevent water from flooding the nest. In the nest of some ant species (Camponotus truncatus, cephalotes), the door is formed from the head of a soldier who obstructs the entry and moves only when a member has to leave or enter the ant nest. Ants living in temperate climates, build nests architected so that most of the building is exposed to the sun and that to maintain a comfortable temperature inside during the winter.
Other species build their nest under a stone, and warming, is the radiator makes it particularly comfortable and the room directly under the rock where he often housed queens and eggs. The land which has made a nest does not crumble because it is cemented with saliva and long work with the mandibles, with this mixture, the ants can build walls, pillars and well-polished up to get hives of up to several floors. The ants are living in trees in natural cavities of the bark and trunk, extending and prolonging the openings and hollows formed with cardboard.
Wonderfully clever are the nests of ants living on the leaves, such as species of the genus Oecophylla and some Polyrachis. They are made with the cooperation of the larvae, which secrete silk threads. Some workers put together take the leaves, while larvae and other grab seek to secrete silk from the larvae move to another corner of the leaves, creating a very dense and durable fabric that holds together the leaves and defines a kind of room . This way of using the larvae, as a real working tool, is an example perhaps unique in nature.
The foundation of a new nest is the work of the queen and this is it for a period of living and working very hard. After being fertilized, and after spawning itself must be taken to provide food and defend the larvae until they have become mature. As soon as the workers and soldiers are able to work you take on the task of providing food and to extend the stay. For a certain period, the Queen cooperate at work, when the nest is now populated only the queen to lay eggs. Often coexist in the same nest as queens, or new queens swarm to form a new company. It is not unusual to get into queens in ant queens becoming adoptive others. Other times, the new queen usurps the throne to their rightful owner killing her.
The artificial ant
Around the lives of ants, especially those living in temperate climates, you know many things, but many remain to be discovered, especially for what concerns the ants of tropical climate. To study the habits of these insects, not just observe what you see in nature, it is necessary to resort to rearing in the laboratory in artificial nests, with walls of glass, making it possible to see how life takes place inside the anthill . An artificial ant is divided into different rooms or rooms must be kept in conditions of temperature, light, humidity, similar to natural ones. External to the ants move in search of food and deposit of waste material, in addition, must be isolated, for example, should a ditch filled with water to prevent ants from escaping. Using these artificial nests, the entomologists (ie, those who study insects) have been able to see many aspects of the secret life of ants and know the relationships between the various members of society and between them and animals, friends or enemies that populate the outside world.
Determination of the caste
Ants are found in various forms of caste determination. In the vast majority of species, the workers develop from eggs anfigoniche on which the queen secretes a special pheromone that inhibits the development of the reproductive organs. In some species of the subfamily Hypoponera, however, there is a determination of caste-based Food: The larvae are fed with more food become queens, while those fed poorly become workers. Neotenina The role of central importance in many species of ants, in the determination of the working caste, a higher level of neotenina allows the development of workers' bigger and bigger.
The ability to overcome obstacles in the environment outside the nest is mainly due to the collective intelligence of ant colonies. Individual workers, however, have a willingness to learn and relatively well-developed individual intelligence. Laboratory experiments show that the workers can easily untangle a maze of medium complexity, while the supply capacity that exploit food resources in the environment outside the nest. Here, the workers are moving through the movement of the sun ( as most insects) and references materials, in addition to traces of pheromone released on the surface of the ground by her companions.
The worker ants spend their time when not feeding the larvae and collect the food to the nest to the outside environment dedicated to the cleaning of the body or to the game. The ants crawling over, clean the antennas of the lower legs, which has a shape with a spatula. The game between the specimens workers is similar to that between domestic animals: ants bite and attack each other, but without injury. The ants also spend part of their time sleeping in holes in the ground placed inside the nest. Upon awakening, often led by her companions, the ants are ironed and "yawn" spreading the jaws.
According to a study done by Matthias Wittlinger and also reported by the National Geographic it seems that the ants are able to find our way back, simply counting the steps. According to this theory, the ants have a sort of automatic counting of steps "that will be reset on return to the nest, even if the hypothesis is that of" chemical attraction ". According to other theories, the ants do not count the steps to return to their nest, but leave behind a fragrant substance below to return to their colony.
The ants are also very selfless for the good of the community while on the move and searching for food, in fact, some specimens fill the potholes they encounter along the way with their bodies, by passing them above the others. This "instant repair" of the course allows them to get more food in less time.
Communication via stigmergy
The worker ants communicate with each other by sending in the pheromone, a volatile chemical that we can perceive smell. Pheromones are primarily used to send warning signals to her friends in an emergency or to reach the food source closer to the nest. While exploring, in fact, the workers Scouts issue along their path a trail of pheromones on the ground. Once you find a food source, they return to nest retracing the same trail of pheromones released during the first leg. At the anthill, then, the workers pickers walk the trail pheromones released by the explorer to find the source of food and supplies. The traces of pheromones on the ground generally last few weeks, but are mixed several times by the workers.
The best-known species
The best-known ant species common in temperate areas and species most relevant are shown in the following list:
the dark ant, common in meadows, where the pupae are kidnapped by Amazonian ant is a kind of slavery that bound
the wood ants, with rust-red livery, abdomen, legs and antennae brown. This species has no sting, but is capable of launching up to 30 cm distance, powerful jets of formic acid produced by an abdominal apparatus. Widespread in the forests of conifers, especially pine and larch, Europe, builds huge nests, up to 2 m high, which is transplanted in other forests in the fight against harmful insects
the harvester ant, which accumulates in seeds and fruit dry rooms and, later, through saliva, reduces these supplies in a kind of food he serves food to the larvae.
Herculean ants and ants rovinaboschi, digging tunnels and cells in the conifers, oaks and holm
the honey ant of Mexico and southern United States, whose workers collect the sugary liquid from the gall of some oaks, and go back to the nest to regurgitate the workers who have only job is to function as food reservoirs
leafcutter ants (genera Atta and Acromyrmex), who live in tropical America and are so called because the workers cut the predator leaves, crush the chips, reduce them in small masses that stick together, incorporate them into a mass of plant materials on which they grow a fungus, which then feed on: a great many colonies are particularly harmful
the ants, so called because when they invade a territory, each animal is forced to leave their home
legionary ants, or ants, soldiers, armies or ants;
the Argentine ant
Characteristics of some species
Among the many species have some curious and interesting features. For example, ants of the genus Messor, specializing in the collection and storage of seeds, and the ants of the genus Atta, the leafcutter notorious, widespread in South America, cultivating a particular fungus, which they feed. The colony of Atta was rigidly divided into castes, each specializing in a specific task, from minor workers and a few millimeters, which is involved in the cultivation of the mushroom, the more workers who are dedicated to the transport and removal of leaves, the soldiers in charge defense of the nest, his head large as 6 mm. Atta a nest may contain millions of individuals and in one night is able to strip a big tree of all its leaves.The leaves, shredded and chewed by workers' children, serve as bedding for the cultivation of fungal mycelium, which constitute the staple food of the colony. The environmental impact of these colonies, makes Sexdens Atta and Atta Chepalotes, the most damaging insects of South America, capable of destroying crops worth billions of dollars. Normally ants insects are considered peaceful, but there are also very aggressive. For example, ants of the genus Eciton, or legionary ants, which live in the Amazon, which gather in huge armies marching through the forest catching all kinds of insects and looting everything in their path. Ants are probably the largest and most dangerous kind of so-called Bulldog Myrmecia, living in Australia.
Aggressive and huge, these insects can grow up to 2.5 cm in length. There are also poisonous, some mushroom pickers. Finally, some species of ants house and protect species of aphids rather than prey in exchange for their sugary secretions, honeydew.
This is a very particular example of symbiosis between the two insects, that curiously resembles the relationship between humans and pets.
In Europe, the most widespread species is probably the red ant, which is considered a protected species in many areas because it will remove the carcasses of millions of insects and makes the soil fertile.
Of all the species only thirty are spread all over the world. About five hundred species live in tropical and equatorial regions, eight hundred and fifty species inhabiting the Mediterranean basin and eight hundred other species are typical of temperate and cold regions.
The larger ants live in hot countries and are predatory and carnivorous, belong to the subfamily Ponerine. Mirmicine ranks among the most species in Europe. Dolicoderine belong to the Argentine ant Linepithema humile and Tapinoma and several species common in our gardens. Formicine the subfamily belong to the more evolved species, are also widespread in temperate and cold countries. Include the genera Camponotus, and Formica Myrmecocystus.
Lifestyles of the ants
Ants are nomadic
Colonies of some ant species, mostly exotic, do not achieve a permanent nest and moving constantly in search of food, altering migration phases with phases sedentary. During the latter, the colony builds a temporary nest, where the queen lays eggs. Once the eggs have developed in adult specimens, the colony leaves the nest and is part of a migration phase, during which moves continuously. In migration, the queen is constantly protected by the workers, while the latter are arranged in straight columns and prey on small animals that are on the path. The columns are formed due to traces of pheromones released by the workers in the front row during the journey.
Workers in many species of the subfamily Formicinae are able to fill the abdomen with liquid, which then distribute them to classmates for trofallassi. In particular, in the colonies such Myrmecocystus, some specialized workers fill the abdomen of liquids and hung from the ceiling of the nest, spreading gradually substances contained within their abdomen to her friends. Among the ants that have an abdominal stretch, there are also species of the genus Lasius.
The dulosi: slave ants
The phenomenon of dulosi, or social parasitism, is common in species of the genus Polyergus and some of those belonging to the genera Lasius, Formica and Aphaenogaster. In the colonies of these species, the workers use to invade the nests of neighboring colonies, often belonging to particular species, to steal and transport the larvae to their nest. These then, are raised and become part of the colony as workers enslaved, thus creating a diverse society. Once purchased the smell of the colony of slavery, the enslaved workers to remain "faithful". Among the species of ants who do dulosi, stand forced slavery (which can not feed themselves and have to resort to the workers of other species), and optional slave (who do social parasitism only to increase the population of workers in their colony ).One example - the only - are forced slave ant species of the genus Polyergus. The winged females of a species form new colonies forced slave introduce into nests of other species, and killing the queen. Then, the females take his place and assume the smearing his scent with his members, so as not to be recognized by workers as intruders. They thus begin to lay eggs, and replace the old working-class population of the colony with specimens of their species. This method, commonly called "usurpation" is also used by some species of the genera Myrmecia and Bothriomyrmex.
Some species of ants use to cultivate the mycelium of a fungus inside the nest, which fertilized with plant debris or pieces of leaves cut for food. They cultivate particular species of Basidiomycetes fungi, which protect them from pests and constantly wet with saliva. The workers do not develop from the mycelium of the mushroom fruiting bodies, since they only feed on the hyphae. To avoid the formation of fruiting bodies, workers bind the hyphae to form pockets. The winged females, before swarming outside the nest, levying the mycelium and transport between the jaws during swarming. Then, they once dug a hole, deposit it and begin to lay eggs. The former workers of the new colony began after fertilizing the fungus, thus forming a crop. Oricoltrici between species, is reminiscent of the genera Atta and Acromyrmex.
The species within the genus Myrmica and Formica are parasitized by a beetle, the Lomechusa, which penetrates in the colonies and gives a sweet substance from worker ants trichomes, the hairs on the bottom of the elytra (forewings that protect the beetles' s abdomen). The substance Lomechusa offered by the worker ants to act as a "drug" that the ants can not do without, and that makes them vulnerable. Once addicted, the workers of the colony in the nest parasitized host the Lomechusa and stop treating their children. Thus, the Lomechusa feeds on the larvae without reaction by the worker ants. The colonies are parasitized by Lomechusa consist of doped worker ants, which die soon after leaving the nest empty. Species parasitized by Lomechusa ants are commonly called "lomecusomani.
Some species of ants distributed in subfamilies Ponerinae and Myrmicinae, prey on small arthropods using traps that snap their jaws as quickly to the passage of the prey. The workers of these species, commonly called "ant traps" lurk for long periods of time awaiting the arrival of prey. When it touches the sensory hairs of the jaws, they snap into fractions of a second, capturing prey
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