Dinoponera gigantea

Dinoponera gigantea
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Ponerinae
Tribe:	Ponerini
Genus:	Dinoponera Roger, 1861
Species:	Dinoponera gigantea Perty, 1833[1]

Dinoponera gigantea is one of the world's largest species of ant.^[2] It is found only in South America. The females of the species are larger than males, with lengths ranging from 3 to 4 centimetres (1.2 to 1.6 in). ^[3] The females are coal-black in color, while the much smaller males are dark red.

Nesting

D. gigantea colonies have as many as eight entrances to their underground chambers, each being 3 to 8 centimetres (1.2 to 3.1 in) in diameter. The entrances are, as is typical for ants, surrounded by the soil removed to make the nest, but, in contrast with other species, no mound is formed. Nests have been found to be about 40 centimetres (16 in) deep, with chambers approximately 3 centimetres (1.2 in) in height and 20 centimetres (7.9 in) in width.

At least in some instances, the species is polydomous, with a single colony occupying and maintaining more than one nest at a time. Some instances of this were recorded in Fourcassie and Oliveira's 2002 study, which found colonies using multiple nests, the entrances of which were 40 to 250 centimetres (1.3 to 8.2 ft) apart.

Foraging

Activity outside the nest is highest at sunrise and sunset, though there some activity likely occurs at night. Individuals search for food alone, generally within about 10 metres (33 ft) of the nest. Items brought back range from 10 to 400 milligrams, and are of wide variety, including both plant and animal matter. Food items include fruits of vismia plants, inga seeds, and various small animals such as spiders, crickets, and snails. A relatively small number, around 10%, of foraging trips turn out to be successful. Successful foraging trips are typically thirty to sixty minutes in duration, though they may take as long as three hours.

Territorialism

Neighboring colonies of D. gigantea have distinct foraging areas. On the occasion that ants from different colonies meet on the border of these areas, the individuals face each other, locking their mandibles. The two then repeatedly poke each others' head with their antennae while kicking with the forelegs. At some point, one of the ants gains a dominant position, eventually biting the other on the top of the head and pressing the gaster against the loser's body. The entire encounter can last up to half an hour. In Fourcassie and Oliveira's study, both ants were invariably found to be uninjured.

References

1. ^ "ITIS Standard Report Page: Dinoponera gigantea". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=583043. Retrieved 30 December 2008. 
2. ^ Zahl, Paul (May 1959). "Giant Insects of the Amazon". National Geographic (Washington, D.C.: National Geographic Society) 115 (5). 
3. ^ Fourcassie, Vincent; Oliveira, Paulo (2002). "Foraging ecology of the giant Amazonian ant Dinoponera gigantea (Hymenoptera, Formicidae, Ponerinae): activity schedule, diet, and spatial foraging patterns". Journal of Natural History (Taylor and Francis) 36.