Cronaca, in
Ant ecocide
points to
Ants
Murder Competing Trees at discovery.com:
[Researchers reporting in Nature]
planted two saplings of a common Amazonian cedar tree (Cedrela
odorata) inside each garden near the base of an ant-infested D.
hirsuta tree.
A sticky insect barrier was applied to one cedar sapling to prevent
ants reaching it, while the other sapling was left untreated.
Worker ants immediately attacked the untreated samplings by
injecting formic acid from their poison glands into the leaves,
which began to to die within 24 hours. ...
But cedars treated with the insect barrier thrived.
The results rule out one of the main theories of devil's gardens
formation, known as allelopathy. Under this process, trees release
toxic secretions that kill competing plants.