Acromyrmex niger
| Acromyrmex niger | |
|---|---|
 | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Myrmicinae |
| Tribe: | Attini |
| Genus: | Acromyrmex |
| Species: | A. niger |
| Binomial name | |
| Acromyrmex niger F. Smith 1858 | |
Acromyrmex niger is a species of New World ants of the subfamily Myrmicinae of the genus Acromyrmex. It is found in the wild naturally in southern Brazil and Paraguay.
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.
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 niger 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. The queens have a high rate mortality that are attributed to conspecific executions and predation, with one study showing that only 13 out of 154 colonies survived.
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 niger lay down pheramone trails to direct other members of its colony to important resources. The strength which members of the colony stick to the trail (trail fidelity) is not determined by colony complexity, but is due to environmental factors, such as the quality of the resource.
Synonyms
- Acromyrmex depressoculis Gonçalves, 1967
- Acromyrmex homalops Gonçalves, 1967
- Acromyrmex muticinoda Gonçalves, 1967
- Oecodoma nigra F. Smith 1858
References
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Wikimedia Commons has media related to Acromyrmex niger. |
1. Fernandez-Marin, H., J. K. Zimmermann, and W. T. Wcislo (2003) Nest-founding in Acromyrmex octospinosus (Hymenoptera, Formicidae, Attini): demography and putative prophylactic behaviors. Insectes Sociaux 50:304-308.
2. Schultz, T. R., D. Bekkevold, and J. J. Boomsma (1998) Acromyrmex insinuator new species: an incipient social parasite of fungus-growing ants. Insectes Sociaux 45:457-471.
3. Wetterer, J. K. (1991) Foraging ecology of the leaf-cutting ant Acromyrmex octospinosus in a Costa Rican rain forest. Psyche 98:361-371.