Paraponera clavata – Isula/Bullet ant

The isula ant, as it is commonly known in Peru is part of the primitive ant subfamily Ponerinae. This ant is also known as ‘bullet ant’ due to the extremely painful sting, which has been compared to being shot by a bullet. Another name given to it by the locals in Brazil, is “Hormiga Veinticuatro,” meaning that the pain from the sting can last 24 hours. Apart from being renowned for its viscous sting, it’s also characterized for its large size. Workers can reach up to 1 inch long (18-25 mm) and look somewhat like wingless wasps. Their stingers are morphologically similar to those of some solitary wasps, which were in fact the ancestors of ants.

The pain experienced when stung by this insect has been said to be 30 times more painful than a common wasp sting. According to the Schmidt Sting Pain Index the sensation from the sting is decribed as causing “waves of burning, throbbing, all-consuming pain that continues unabated for up to 24 hours”. The venom has been analysed and a paralyzing neurotoxic peptide, poneratoxin, has been isolated. This neurotoxic venom blocks the central nervous system transmission in arthropods, but in mammals, it causes tremendous pain.

Paraponera is not an aggressive ant, by nature. It is only so, when it defends itself or its territory. For instance, when something disturbs its nest, the ants swarm out, releasing a strong odor which acts as a warning to intruders. Next, they proceed to grab and sting trespassers.

Although these ants may seem like the kings of the jungle, they still have predators and parasites that can attack them. The isula’s natural enemies include other bullet ants from different colonies, the parasitic Phorid flies, and even entomopathic fungus that infect the ants, leaving their spore-bearing remains stuck on vegetation.

Bullet ants can be found in Atlantic coastal lowland rainforests. In Peru, it resides in both primary and secondary rain forest growth, and according to a small study by Tobin 1991, it was the third most abundant ant of 52 canopy-dwelling species.

Mature colonies of Paraponera clavata, meaning those producing reproductive forms, are generally small in size, containing a maximum of a few thousand ants.  As they are considered to be relatively primitive, the queen and the workers vary very little in size, meaning there is no polymorphism.  The queen alone is capable of starting her own colony, and the colonies are monogynous, meaning that there is only one single mated queen. As for the workers, there is a division of labour, which is dictated by their size. The larger workers serve as nest guards and foragers, while the smaller ones are nursemaids, tending to the brood inside the nest.

The nests of these ants are generally in the ground, at the base of trees, but they can also be found in arboreal cavities. Their nests often have a single entrance, but may have multiple openings. The secondary openings may be used for soil removal. The nests tend to have many chambers, all varying in size (5-10 cm in diameter) and situated at different depths, from some 7 cm to some 60 cm below ground. It has even been observed that these nests contain drainage or escape tunnels under the deepest chambers of the nests.

The temperature in the nest varies between 22-27^oC. Pupae and occasionally large larvae are incubated in the warmest sites. It has been observed, when reared in laboratory, that colonies grow normally, but possibly more slowly, under relatively uniform conditions (22-23 ºC.).

These ants are predator-scavengers feeding on liquid droplets, prey, and plant parts. The main component of their diet consists of extra-floral nectar. Water is also collected by the foragers and both nectar and water are shared with nest ants, or placed as tiny droplets on feeding larvae.

In laboratory, it has been observed that food diversification is quite important since the ants seem to get bored of the same prey when given to them several days in a row. The foods they have been known to eat in laboratory include various termite spp. (Isoptera), roach spp. (Dictyoptera), cricket and katydid spp. (Orthoptera), walking stick spp. (Phasmatoptera), meal worms and adults (Coleoptera), wax worms (Lepidoptera), and bottle flies (Diptera).

In the past, some indigenous people used bullet ants in their initiation rites to manhood. The elders in the tribe would first sedate the ants by drowning them in a natural chloroform and then would weave them into special gloves made out of leaves, with the ants’ stingers facing inward. Then, once the ants would begin to wake up, the young boys had to put on the gloves and last 10 minutes without showing any sign of pain. After these 10 minutes, the boys were considered men. However, since the venom of these ants is so potent, their arms were temporarily paralyzed and they often would shake hysterically for days.

References:

“Bullet Ants: Paraponera clavata.” AntBlog. 19 July 2009 <http://www.antblog.co.uk/species/bulletants.htm&gt;.

“Bullet Ant.” Painful Bite — Most poisonous and dangerous creatures. 21 July 2009 <http://www.painfulbite.com/bullet_ant.php&gt;.

Morgan, Randy C. . “The Natural History of Bullet Ants.” Sonoran Arthropod Studies Institute, SASI Online, Bugs, Insects, Arachnids, entomology and more.. 19 July 2009 <http://www.sasionline.org/antsfiles/pages/bullet/bulletbio.html&gt;.

Tobin, J.E. (1991). A neotropical rainforest canopy, ant community: some ecological considerations. In: Ant-Plant Interactions (Husley, C.R. and Cutler, D.F., Ed’s.). Oxford University Press. p: 536-538.