Army ant

As army ants, driver ants or army ants also called ant species are summarized, all of which have a set of common behaviors coupled together, the " driver ants syndrome " (English "army ant syndrome" ). Most species with this behavioral syndrome constitute a group with each other related subfamilies Dorylomorpha. In addition, it is less common and at a series of other species which are not closer related to each other and belong to different sub-families. Other types show only some, but not all, of the characteristic behaviors.

• 7.1 food
• 7.2 raids

The army ant syndrome

The following behaviors are characteristic of the driver ants:

• Hunting only in groups. Typical of ants swarming is an individual scouts who recruit Assist in discovering more food workers. When army ants hunting from the beginning in groups takes place, take off together as " army trains ". These may include hundreds of thousands of individuals. The army trains are connected by reciprocating individuals permanently to the nest.
• Periodic relocation of the nest site. Ants have a nest or a designated bivouac above-ground location in which they return to their raids. This nest is laid but after a certain time, and the entire colony moves to a new location in order. Other ant species can shift their nest, but do so usually only when external disturbances.
• Army ants reproduce exclusively through wingless queens by fission or budding of the mother colony. The young queen takes off with part of the workers to their mother colony. New colonies are therefore not justified by independent nest founding a queen with her own offspring.
• The queens of migrant species of ants are always very large in relation to the workers. My abdomen is swollen to accelerate egg production and distended ( " physogastrisch ").

These behaviors are coupled to each other. As a starting point and origin of Verhaltensssyndroms applies the group hunting. By hunting in groups particularly large and well-fortified prey can be overwhelmed. In addition, colonies of other social insects, which are often well defended and fortified, can be overcome and captured. Through the group hunting the food base in vicinity of the nest but is exhausted more quickly; thus the move is forced. As for successful group hunting from the very beginning many workers need to cooperate in the individual nest establishment must be abandoned.

Other common features are found in many, but not all army ants. Thus, many species to an extreme Größenpolymorphismus of workers with workers of different body size, which form sometimes sharply divorced from each other sub-castes. Most have, despite the great nation strengths that millions may include individuals, only a single queen. Many species also have complex life cycles in which stationary breeding sites and mobile migrant phases alternate in a lawful way.

The "real" army ants

As actual or real army ants three related subfamilies of ants are known, the Ecitoninae, Dorylinae and Aenictinae, combined to the Dorylomorpha. In the New World were exclusively those Ecitoninae before, in the Old World and the Dorylinae Aenictinae. The army ants, a State may comprise up to several million animals in extreme cases. Thus, the African migrant ant Dorylus wilverthi constitutes States with more than 20 million individuals. Without exception, all species of this lineage show the complete driver ants syndrome, as far as their biology is known.

Other Ants

Outside of this kinship group, there are some species in a more or less perfect expression also show the same behavior pattern. All elements are, for example, in some species of the genus Leptogenys ( subfamily Ponerinae ) and the genus Pheidologeton ( subfamily Myrmicinae ) to find that they both live in the tropical East Asia. Other genera have been reported for the comparable behaviors, such as Cerapachys, Leptanilla, Onychomyrmex, Pachycondyla. Most individual behaviors are here but different. So hunt eg many Leptogenys species not originally collective, but be transformed by scouts, but change the Niststandort regularly. Some Pheidologeton species is obligate group hunting, but no change of Niststandorts reported.

Occurrence

The distribution of the army ants extends over the tropics and subtropics of the Old World as well as the New World. They are found in Africa, Asia, South America, and Central America.

Nomadic and stationary phase

Ants have two different phases of activity: A nomadic (wandering ) phase and a stationary phase. Regularly, this change in the South American Eciton species from. For most other army ants the phases go more into each other.

Nomadic phase

In the nomadic phase, the ants wander in the day, prey on insects, spiders and small vertebrates and form at Dusk their nest, which they change almost daily. The trails are in some species protected by soldiers. During their hunt they are accompanied by birds of different species, such as birds and ants specialized choke and wren species that destroy the startled insects. Among the army ants there are also species that appear only at night. Through its activity, there are no adequate studies. Among the army ants Eciton burchelli and diurnal species Eciton hamatum are the most studied representative.

Stationary phase

The stationary phase, which is about two to three weeks, begins when the larvae pupate. Now, the earlier the larvae fed prey is only presented to the Queen. The abdomen (gaster ) of the queen swells strongly, called Physogastrie, and it comes to laying eggs. Coinciding with the hatching of the larvae leave the new workers their cocoon and the army ants take back after their nomadic hiking phase.

Nesting

The Eciton species build no nest at all like most ants, but form with their bodies a living nest, which is called in the jargon " bivouac ". Bivouacs are in a protected location, such as applied to tree trunks. Here, the members hold each other tight on the legs to form a sort of ball that appears unstructured for laymen, but represents a well- structured entities. The older workers are on the outside; inside there are the younger workers. At the slightest disturbance collect on the surface of the bivouac soldiers, with strong jaws and ( in the case of Aenictinae and Ecitoninae ) armed with spines to defend the nest. The nest is crisscrossed inside with numerous dikes and includes a plurality of chambers with food, the queen and the larvae and eggs. Other army ants build mostly in soil, in which it also may lead to bivouac -like aggregations.

Food and raids

Food

Ants can to capture the prey 100,000 per day, and so have a significant influence on the occurrence, diversity and also on the behavior of their prey. The prey spectrum is very different for each species. Subterranean species prey mainly soil-dwelling arthropods and their larvae, earthworms, and occasionally juveniles of vertebrates, turtle eggs or oil-containing seeds. A majority of the species has specialized in the breeding of other ants and wasps ( the columns Raiders ). Only the few species with large swarm raids seem to have a really wide food spectrum. Nevertheless, capture, and also eat these types not every animal. While even small vertebrates that get into the raids, are killed, the jaw of the American Eciton species are not suitable for dividing this booty in contrast to the African Dorylus species. (You will be allowed and utilized by scavengers or swarm - accompanying flies. ) Only a few species hunt at all about the earth's surface, where they are mainly looking for in the leaf litter and low vegetation for prey. Also in higher trees hunt about 5 species that can attack birds and eggs there, but mostly prey on other social insects and their eggs and larvae.

Raids

In their raids, the army ants use two patterns: column raids and swarm raids. The species Eciton hamatum is a typical representative of the columns raids. The swarm members separate raids in the side of the main route and form small foraging groups, similar to a tree with its branches. The individual side paths can have a large distance from each other. Eciton burchelli selects the swarm attack. Also it has initially a main route, which then splits as in an umbel in many branches, but are the individual side paths close together, cross over several times so that the individual troops effectively cover a larger area. The column may be, fan out up to 20 meters.

Genera and species ( selection)

The ants are counted around 150 species in the New World and about 100 species in the Old World.

• Subfamily Aenictinae

Distribution: Asia in particular, as well as several African species. The subfamily is represented by only one genus Aenictus. The genus is characterized by the lack of large morphological differences from ( eg there are no soldiers or significantly smaller workers ). The majority of the species that lives underground, with some above ground active species.

• Subfamily Dorylinae

Distribution: Mainly Africa; about 5 Asian species. The subfamily is represented by only one genus Dorylus. This is in turn divided into five subgenera: Anomma, Dichthadia, Dorylus, Rhogmus and Typhlopone.

• Dorylus ( Anomma ) wilverthi and D. (A. ) nigricans are the most famous above ground hunting African driver ants.
• Dorylus ( Dichthadia ) laevigatus lives in Asia and is the most primitive species of the genus.

• Subfamily Ecitoninae

Distribution: southern United States via Central America to Argentina. The subfamily is divided into five genera:

• Cheliomyrmex. This is the most primitive genus of the subfamily. Thanks to the fully underground deposits, little is known about the lifestyle of known species.
• Eciton. This is probably the best known driver ant genus, as there are many studies on the biology and behavior of the aboveground hunting species Eciton burchellii and Eciton hamatum.
• Labidus. In this genus comes with the kind Labidus predator also present an above ground hunting Treiberameisenart. Although not necessarily rare, drop the other species by its more hidden life on less.
• Neivamyrmex. This genus is represented by a large number of mostly very small species, whose biology is known for its predominantly subterranean lifestyle little.
• Nomamyrmex. With only two species with four subspecies, this is the least species driver ant genus. Described are N. esenbeckii ( NE crassicornis, NE mordax, NE wilsoni ) and N. hartigii.

More

The Maasai use the army ants to suture wounds. Set the ants at the wound edges and the ants bite in the skin. After the bodies of the ants are separated.