Tetraponera

Tetraponera
Tetraponera rakotonis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Pseudomyrmecinae
Genus:	Tetraponera Smith, 1852
Species
Many, see text

Tetraponera, or slender ants, is a genus in the family Formicidae, and are characterised by their arboreal nature and slender bodies. There are 86 described species of Tetraponera all of them living in hollow structures of plants and trees, such as thorns or branches, these hosts are known as myrmecophytes. Tetraponera are closely related to the new world genus of ants Pseudomyrmex but differ in their relationships with host plants.

Mutualisms and behaviour

Tetraponera species are generally defined by the myrmecophytes that they inhabit and the mutualistic relationship they share.^[1] These host plants always have hollow thorns or branches in which the ants can live and form a colony. Also the myrmecophytes provide energy rich food sources such as extrafloral nectar (EFN) and/or food bodies (FB). For all Tetraponera species there are gut symbionts that allow them to digest amino acid deficient food such as that provided by their host plants, these gut bacteria are especially important for the species that only survive on the myrmecophyte EFNs or FBs.

All Tetraponera provide protection for their host plants through aggressive nature towards other insects and trimming leaves/branches of neighbouring plants. Living in hollow structures of the plants allows the ants to detect vibrations when larger insects land on the plant or workers on patrol visually detect smaller intruders. Once detected sophisticated pheromone systems allow Tetraponera to quickly outnumber and overpower any invaders. Most insect invaders are killed and discarded by Tetraponera workers such as caterpillars and aphids but some are killed and consumed. The insects that take the most time and effort to kill are generally consumed; these are mostly katydids or leaf beetles.

As well as assaulting and killing insects that attack their host plant Tetraponera will attack any mammals that present a threat as well. Inflicting the mammals with painful stings will usually deter them from attacking the plant.

In some arboreal ant species, not just Tetraponera, a third partner in ant-myrmecophyte mutualisms is Hemiptera trophobionts. These insects provide a possible third source of food for the ants, in return the ants feed and “nurture” the Hemiptera inside their colony.

Distribution

Tetraponera are found commonly in the warmer regions of Africa, Asia and Australia. Different species of Tetraponera are associated with different plant species. The most common myrmecophytes for Tetraponera are acacias but there is a wide variety of hosts for this genus including bamboos and lianas. Tetraponera trim neighbouring plants to prevent any intrusion of ants or caterpillars from those plants and to reduce resource competition for their host. Tetraponera will only leave their myrmecophyte to start a new colony on a different host, a queen and a number of workers will leave the old host plant to allow the colony to continue to expand.

Life cycle and castes

A slender ant worker

Tetraponera like most ants have one or a few queens that are the only females to reproduce in a colony. The sterile workers are all females that forage for food and defend the colony. Males are produced only during certain times of the year and disperse to mate with virgins queens from other colonies. Since ants are haplodiploid they can control what sex their offspring will be; an unfertilised egg will become a male while a fertilised egg will be female. This reliably restricts the production of male alates to the species's mating season, when the winged virgin queens and males fly from their home colonies to mate and start new colonies.

The eggs produced by the queen hatch into larvae which are cared for inside the colony, protected from any predators by the workers. The amount of care each female larva receives determines its fate as a worker or a new queen; all males are drones. When a new colony is formed eggs are initially produced at a low rate, but this quickly increases in the second to fourth years, ensure that there are enough workers to protect and provide for the growing colony.

Species list

References

External links

• Media related to Tetraponera at Wikimedia Commons