Ants (wikipedia)

society:

Not all ants have the same kind of societies. The Australian bulldog ants are among the biggest and most primitive of ants. The individual hunts alone, using its large eyes instead of its chemical senses to find prey. Like all ants they are social, but their social behavior is poorly developed compared to more advanced species. An Australian bulldog ant, Myrmecia pilosula, has only a single pair of chromosomes and males have just one chromosome as they are haploid.

Some species of ants are known for attacking and taking over the colonies of other ant species. Others are less expansionist but nonetheless just as aggressive; they attack colonies to steal eggs or larvae, which they either eat or raise as workers/slaves. Some ants, such as the Amazon ants, are incapable of feeding themselves, and must rely on captured worker ants to care for them. In some cases ant colonies may have other species of ants or termites within the same nest.[27]

The pavement ant is famous for its urge to increase its territory. In early spring, colonies attempt to conquer new areas and often attack the nearest enemy colony. These result in huge sidewalk battles, sometimes leaving thousands of ants dead. Because of their aggressive nature, they often invade and colonize seemingly impenetrable areas.

Ants identify kin and nestmates through their scents, a hydrocarbon-laced secretion that coats their exoskeletons. If an ant is separated from its original colony, it will eventually lose the colony scent. Any ant that enters a colony with a different scent than that of the colony will be attacked.


agriculture:

Leafcutter ants (Atta and Acromyrmex) feed exclusively on a special fungus that lives only within their colonies. They continually collect leaves which they cut into tiny pieces for the fungus to grow on. These ants have several differently sized castes especially for cutting up the pieces they are supplied with into even smaller pieces. Leaf cutter ants are sensitive enough to adapt to the fungi's reaction to different plant material, apparently detecting chemical signals from the fungus. If a particular type of leaf is toxic to the fungus the colony will no longer collect it. The ants grow the fungus because it produces special structures called gongylidia which are fed on by the ants. They create antibiotics on their exterior surfaces with the aid of symbiotic bacteria, and subsist entirely on this farming of the fungus.


relation with other species:

Aphids secrete a sweet liquid called honeydew. The sugars provide a high-energy food source, which many ant species use. Normally this is allowed to fall to the ground, but around ants it is kept for them to collect. The ants in turn keep predators away and will move the aphids around to better feeding locations. Upon migrating to a new area, many colonies will take new aphids with them, to ensure that they have a supply of honeydew in the new area. Ants also tend mealybugs to harvest their honeydew. Mealybugs can become a serious pest of pineapple if ants are present to protect mealybugs from natural enemies.

Myrmecophilous (ant-loving) caterpillars of the family Lycaenidae (e.g., blues, coppers, or hairstreaks) are herded by the ants, led to feeding areas in the daytime, and brought inside the ants' nest at night. The caterpillars have a gland which secretes honeydew when the ants massage them. Some caterpillars are known to produce vibrations and sounds that are sensed by the ants.[35] Some caterpillars have evolved from being ant-loving to ant-eating and these myrmecophagous caterpillars secrete a pheromone which makes the ants think that the caterpillar's larva is one of their own. The larva will then be taken into the ants' nest where it can feed on the ant larvae.

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