Allomerus decemarticulatus is an Amazonian ant species found in the tropics of South America.
A recent study performed by Céline Leroy et al. (2008) revealed many characteristics that the plant has adapted to support the ants.
Finally, there was a greater deposit of cellulose found in the domatia, which would result in a thicker cell wall and a more rigid surface to support the weight of the ants.
These findings show that the areas destined to become domatia are inherited and a result of coevolution; they were solely produced to support this specific species of ant.
This fungus is a sooty mold which, according to one study by Mario X. Ruiz-Gonzalez et al. (2010), is characterized by closely related haplotypes (genetic markers) in the order Chaetothyriales.
They strictly manipulate the physiology of the fungus to construct a mortar for a trap that is able to catch much larger prey.
[2][3] The actual production of the trap occurs by first cutting plant hairs (trichomes) from a narrow vertical stretch of the stem outside of the domatia.
The ants will then arrange these hairs to outline the structure of the trap and regurgitate the mold that acts as a paste and holds the trichomes together.
Once an insect lands on the plant, the closest ant will immediately surface and grab on to a leg, antenna, wing, or some other appendage of the prey.
This ability to hold the prey is extremely important because the ants move and congregate fairly slowly.
The first few ants to arrive will each grab a different leg and pull in opposite directions, "spread-eagling" the prey.
So a single Allomerus decemarticulatus worker restraining a grasshopper is about the equivalence of a 175-pound person holding down a struggling 25,000 pound object that is actively trying to escape.
For example, a hind leg of a grasshopper is still about 12.4 times the size of a single ant and a great resource in itself.
[2] If the multiple relationships of A. decemarticulatus were not complex enough, they also commonly interact with an assassin bug, Zelus annulosus, which often resides on H. physophora plants.
However, these bugs have adapted physiological and behavioral characteristics that allow them to avoid the predation of A. decemarticulatus, while also maintaining a mutualistic relationship with the plant.
[6] Similar to the ants, Z. annulosus normally lives on younger H. physophora individuals, where the females lay eggs on the stem.
As they begin to develop, the young bugs will live among the trichomes of the stem and hunt on the leaves of the plant.
Also, the bugs secrete a sticky substance that allows them to walk on top of these trichomes, thus avoiding the traps of A. decemarticulatus.
In regards to the predatory behavior of A. decemarticulatus, similar behaviors have been observed in other ant species, such as symbioses with plants (like in Pseudomyrmex ferruginea),[7] cultivating a fungus (like in leafcutter ants),[8] and sneaking up to and ambushing larger prey (like in Azteca andreae, another species studied by Dejean).
[9] However, most remarkably, Allomerus decemarticulatus seems to incorporate each of these advanced behaviors to make a powerful apparatus for tricking impressively large prey.