Acromyrmex heyeri

Acromyrmex heyeri
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Myrmicinae
Tribe: Attini
Genus: Acromyrmex
Species: A. heyeri
Binomial name
Acromyrmex heyeri
Forel, 1899[1]

Acromyrmex heyeri is a species of leaf-cutter ant, a New World ant of the subfamily Myrmicinae of the genus Acromyrmex. This species is from one of the two genera of advanced attines (fungus-growing ants) within the tribe Attini.

Distribution

This species is found in Paraguay, Argentina, Brazil, and Uruguay.[2]

Overview

Commonly known as "leaf-cutter ants" they are a species of ant from one of the two genera of advanced attines within the tribe Attini.

Head view of ant Acromyrmex heyeri specimen.

Acromyrmex can be identified from the closely related Atta genus of leafcutter ants since they have 4 pairs of spines and a rough exoskeleton on the upper surface of the thorax.

A mature Acromyrmex heyeri colony contains mostly sterile female workers. They are divided into castes, based mostly on size, that perform different functions. Acromyrmex exhibit a high degree of biological polymorphism, four castes being present in established colonies - minims (or "garden ants"), minors, mediae and majors. Majors are also known as soldiers or dinergates. Each caste has a specific function within the colony. Acromyrmex ants are less polymorphic than the other genera of leafcutter ants Atta, meaning that there is comparatively less differential in size from the smallest to largest types of Acromymex. The high degree of polymorphism in this genus is also suggestive of its high degree of advancement.

Like Atta, Acromyrmex subsists mostly on a particular species of fungus (genus Leucocoprinus) which it cultivates on a medium of masticated leaf tissue. This is the sole food of the queen and other colony members that remain in the nest. The media workers also gain subsistence from plant sap they ingest whilst physically cutting out sections of leaf from a variety of plants.

Before leaving their parent colonies, winged females take a small section of fungus into their bucchal pouches and it is with this that the subsequently wingless queens 'seed' the fungus gardens of incipient colonies, cutting and collecting the first few sections of leaf themselves.

Acromyrmex has evolved to change foodplant constantly, preventing a colony from completely stripping off leaves and thereby killing trees, thus avoiding negative biological feedback on account of their sheer numbers. However, this does not diminish the huge quantities of foliage they harvest.

Acromyrmex heyeri workers construct the colonies nest by thatching together cut grass. At temperatures ranging from 20–30 °C, workers created more openings in the nest thatch as the internal nest temperature goes up as a method of temperature regulation for the colony. The workers will close openings in the nest thatch as the air humidity surrounding the nest decreases to reduce water loss for the colony.

Studies using isoenzyme systems MDH, a-GPDH, and AMY show the occurrence of monogyny and polygyny associated or not with polyandry, which indicates that the social organization is colony-specific. The polygyny and polyandry observed are likely to be responsible for the great genotypic diversity of the species colonies. The average inbreeding coefficient per colony is higher in Acromyrmex striatus than in Acromyrmex heyeri, which may reflect the different patterns of production of sexual individuals and nuptial flight of those two species.

Synonyms

See also

References

  1. ↑ "Species: Acromyrmex heyeri". AntWeb. 2010-06-30. Retrieved 2010-08-20.
  2. ↑ http://www.blueboard.com/leafcutters/pics/myrmecos1_4.htm

External links

Wikimedia Commons has media related to Acromyrmex heyeri.