| Dinoponera | |
|---|---|
 | |
| Dinoponera quadriceps –MHNT | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hymenoptera |
| Family: | Formicidae |
| Subfamily: | Ponerinae |
| Tribe: | Ponerini |
| Genus: | Dinoponera Roger, 1861 |
| Type species | |
| Ponera grandis Guérin-Méneville, 1838 | |
| Diversity[1] | |
| 8 species | |
Dinoponera is a strictlySouth Americangenus ofant in thesubfamilyPonerinae, commonly calledtocandiras orgiant Amazonian ants.[2] These ants are generally less well known thanParaponera clavata, the bullet ant, yetDinoponera females may surpass 3–4 cm (1.2–1.6 in) in total body length, making them among the largest ants in the world.
Dinoponera (tocandira ants) are known aspiata in manyTucanoan languages.[3]
Dinoponera is a strictly South American genus, and has been found from montanerainforest on the eastern slope of theAndes inPeru,Ecuador andColombia tosavannah and lowland rainforest inBrazil,Guyana, south throughBolivia,Paraguay andArgentina.[2]Dinoponera australis, known from Bolivia, Brazil, Paraguay and Argentina, has the widest known range of allDinoponera species.[4]
Dinoponera contains one of the largest species of ants in the world, with femaleDinoponera gigantea specimens measuring 3–4 cm (1.2–1.6 in) in length.[5] Size is the most obvious characteristic distinguishingDinoponera from other genera. The only other ants with a worker caste approaching this size areParaponera clavata (the bullet ant) and the largerPachycondyla such asP. crassinoda,P. impressa andP. villosa.Paraponera clavata is easily identified by its anvil-shapedpetiole with a spine on the ventral surface, highly sculptured body and deepantennal scrobes.Pachycondyla is regarded as the sister taxa toDinoponera.Dinoponera, in addition to their size, are distinguishable fromPachycondyla by the presence of two laterally projectingclypeal teeth and rows of spines on thepygidium and hypopygidium.[6]
Dinoponera is one of the roughly 10 ponerine genera in which some species have secondarily lost the typical morphologically specialized queen caste for a reproductive worker known as agamergate. Conflict over dominance is intense in colonies, with younger workers usually joining a linear hierarchy of one to five workers depending on colony size. The gamergate, or alpha female, has the highest ranking. The alpha female mates with non-nestmate males at night at the entrance of the nest.[7] After copulation the female bites through the male's gaster to release herself and pulls out the genital capsule, which acts as a temporary sperm plug. After mating the female is unreceptive to other males and remains monandrous.[8] The gamergate maintains dominance with ritualized behaviors such as antennal boxing and biting, "blocking", as well as gaster rubbing and curling.[9]
Alpha females may "sting smear" a competing female with secretions from theDufour's gland, triggering the lower-ranking workers to immobilize the marked female. Subordinate females (beta, gamma or delta) may produce unfertilized eggs but these are usually consumed by the alpha female in a form of "queen policing".[9]
Males are born throughout most of the year in tropical species; however,Dinoponera australis, which lives in the more temperate south, was found to produce males only in May–July. When the alpha declines reproductively or dies, she is replaced by a high-ranking worker.[10]
Workers lower in the hierarchy forage individually for food items on the substrate and do not recruit other nestmates to assist with food transport.[5] Although foraging workers do not recruit nestmates,Nascimentoet al. (2012) found a positive feedback between incoming food and stimulation of new foragers as well astask partitioning once food was brought into the nest. Lower-ranking females processed protein resources while higher-ranking females handled small food pieces and distributed them to thelarvae. Fourcassié & Oliviera (2002) foundDinoponera gigantea foraging to be concentrated in the early morning and afternoon but did not sample at night.Morgan (1993) observed the highest activity at night inDinoponera longipes.Dinoponera quadriceps has a marked seasonal pattern in activity. It is most active in May–August, the late rainy season to early dry season in the semiarid Caatinga. Activity was strongly negatively correlated to temperature and positively correlated to prey abundance. The diets of bothDinoponera gigantea andDinoponera quadriceps have been shown to be predominantly scavengedinvertebrates, but include live prey, seeds and fruits.Araújo & Rodrigues (2006) state that the taxonomic diversity of prey is comparable to other tropical ponerines, but has an optimal prey size of 2–3 cm inDinoponera. Diet seems to be very similar across the genus, regardless of habitat.[11]
Despite their large size and strongvenom,Dinoponera are likely preyed on by many vertebrate and invertebrate species across South America. Like many other ant species,Dinoponera can be infected by theentomopathogenic fungiCordyceps sp.[12]Buyset al. (2010) discovered aKapala sp.eucharitid wasp emerging from the puparia ofDinoponera lucida.[13]
For subduing large live prey and defense, workers possess asting that has been known to cause severe pain lasting up to 48 hours.Lymphadenopathy,edema,tachycardia and fresh blood appearing in human victim feces are common symptoms.[14] In some ant specimens thevenom sac is empty. Workers may have 60–75 unique proteinaceous components in the venom. The convoluted gland within the venom system ofDinoponera australis has been found to possess close similarities to those ofvespine wasps. The contents ofDinoponera australis venom have been found to be similar to those ofPachycondyla spp. Due to the high diversity of compounds and systemic effects, venom ofDinoponera could be of use to the pharmaceutical industry. For instance,Sousaet al. (2012) demonstrated in mice that venom fromDinoponera quadriceps had antinociceptive properties. The authors note that the local population of northeast Brazil uses dry crushedDinoponera quadriceps ants to treat earaches, and the stings of live ants are administered for back pain and rheumatism.[13]
Colonies vary in size depending upon species, but generally consist of fewer than 100 individuals.[15]Dinoponera australis colonies have an average of 14 workers (range 3–37),Dinoponera gigantea averages 41 workers (range 30–96), andDinoponera quadriceps has the largest colonies, with an average of 80 workers (range 26–238).[16]
New colonies are founded by fission, a process in which a beta female is fertilized in the natal nest.[7] This new alpha female then leaves the nest with a cohort of workers to found an incipient colony, sometimes employingtandem running.[9]
The nest consists of large chambers and tunnels in the soil, sometimes with an earthen mound, and can be 0.10–1.2 m deep. Nests are deeper inDinoponera australis andDinoponera quadriceps than inDinoponera gigantea.Monninet al. (2003) suggests that deeper nests are a possible adaptation to seasons and aridity.Dinoponera gigantea nests may have up to eight entrances and can be weaklypolydomous,[17] whereas 1–30 openings, with an average of 11, were recorded forDinoponera longipes. Nesting density and spatial distribution varies depending on habitat. Density ranges from 15–40 nests per ha to 80 nests per ha.Morgan (1993) measured a spacing between nests forDinoponera longipes with a median of 35 m (n=22, range 14–69.5 m).Dinoponera australis andDinoponera gigantea usually nest at the base of trees. Observations ofDinoponera quadriceps nests show that in more aridCaatinga andCerrado habitats, nests are predominantly constructed under trees, whereas inAtlantic forest 60% of nests were 3 m away from any tree.[16]
This article incorporates text from a scholarly publication published under a copyright license that allows anyone to reuse, revise, remix and redistribute the materials in any form for any purpose:Lenhart P, Dash ST, MacKay WP (2013), "A revision of the giant Amazonian ants of the genus Dinoponera (Hymenoptera, Formicidae)",Journal of Hymenoptera Research,31:119–164,doi:10.3897/JHR.31.4335 Please check the source for the exact licensing terms.