The Web of Life (22-3-11) Amazonian Ant-Plant

 Amazonian Ant-Plant

An arboreal ant lives in the leaf pockets of the Amazonian ant-plant. The ants protect the plants from leaf-eating insects.

On the host plant’s stems, worker ants build galleried structures which they employ as traps to capture larger insects. First, they cut plant hairs (trichomes) along the stem construction site to clear a path. Next, using uncut trichomes as pillars, the ants build a gallery by binding the cut plant hairs together using a sappy regurgitated compound. They leave enough room to maneuver between the stem and the surface of the structure, creating a vault.

This gallery is reinforced with a black, sooty mold of mycelia that the ants cultivate. The mold grows on the goop. The ants cut numerous holes in the structure, just large enough that they can stick their heads through from the vault.

Workers hide in the vault, their heads just under the holes, waiting for prey. The trap is set.

When a large insect lands on the structure, it is temporarily stuck. The workers grab the victim’s body – legs, antennae, wings – and pull on it until the prey is progressively stretched out against the gallery.

Swarms of workers then sting the insect to death. Next, moving in and out of the holes, they slide the banquet-to-be to their leaf pouch where they carve it up.

The ants sometimes get uppity on their host, by destroying its flower buds, to skew the plant’s growth-reproduction ratio to favor more leaves and stems. Plants whose buds have been devastated grow more quickly.

When such exploitation happens, a plant can sanction the ants by producing leaf pockets too small for the ants to use. This teaches miscreant ants respect.