Bullet Ant

Appearance

Workers are 18–30 mm long and resemble stout, reddish-black, wingless wasps. "Paraponera" is predaceous and like all primitive poneromorphs, does not display polymorphism in the worker caste. The queen is not much larger than the workers.

Naming

The bullet ant is called "Hormiga Veinticuatro" or "24 ant" by the locals, referring to the 24 hours of pain that follow being stung.

Distribution

Colonies consist of several hundred individuals and are usually situated at the bases of trees. Workers forage arboreally in the area directly above the nest for small arthropods and nectar, often as far as the upper canopy; little foraging occurs on the forest floor. Nectar, carried between the mandibles is the most common food that is taken back to the nest by foragers. Two studies in Costa Rica and on Barro Colorado Island, Panama, found that there are approximately four bullet ant nests per hectare of forest. On BCI the nests were found under 70 species of tree, 6 species of shrub, 2 species of liana and 1 species of palm. Nests were most common beneath the canopies of "Faramea occidentalis" and "Trichilia tuberculata" but these trees are also the most abundant in the forest. Nests were present more frequently than would be expected based on the abundance of the trees under "Alseis blackiana", "Tabernaemontana arborea", "Virola sebifera", "Guaria guidonia" and "Oecocarpus mapoura". The large number of nest plants suggests that there is little active selection of nest sites by bullet ants. Small shrubs however are under utilised, probably because they do not provide access to the forest canopy. The study on BCI concluded that trees with buttresses and extrafloral nectaries may be selected for by bullet ants.

Defense

The pain caused by this insect's sting is purported to be greater than that of any other Hymenopteran, and is ranked as the most painful according to the Schmidt Sting Pain Index, given a "4+" rating, above the tarantula hawk wasp. It is described as causing "waves of burning, throbbing, all-consuming pain that continues unabated for up to 24 hours". It is thought that the ant has evolved this way to ward off any predators who would normally unearth them. A paralyzing neurotoxic peptide isolated from the venom is poneratoxin. It affects voltage-dependent sodium ion channels and blocks the synaptic transmission in the insect central nervous system. It is being investigated for possible medical applications.