Trees That Trap Ants...

Nov 18, 2013 By Deepa Gopal
Deepa Gopal's picture

Did the title catch your attention? It certainly caught ours when we came across two fascinating studies that reveal how trees control the ants that live on them!

Partnership between different species is very common in nature. Known as symbiosis, it is a great way for two species to share resources for survival. A well known example are the colorful corals one finds in reefs. Did you know that corals are in fact animals belonging to the family Cnidaria, which also includes sea anemones? Corals attract algae that through photosynthesis lend brilliant colors to their hosts. Corals feed off the sugars generated by algae, and release carbon-di-oxide which in turn is used by algae.

However the two tree-ant relationships discovered recently seems more like a form of trickery! 

Laurel Trees Ward Off Pests

The first example of symbiosis takes place in Mexico and Central America, where Azteca ants nest in the stem cavities of laurel trees. During dry spells, leaves of laurel trees are under attack by pests. The tree has evolved a creative solution over the years - it uses the ants that nest in it as bodyguards.

When water levels are low, the laurel tree boosts its sugar production that attracts and supports larger colonies of ants. Any invading pests such as caterpillars are attacked and nibbled on by ants, until they fall off the trees!

Acacia Trees Control Ants

Acacia trees in Central America have gone one step further. The trees once again depend on ants to protect against weeds and pests. But like indentured labor, the trees trap the ants. The sweet nectar secreted by acacia tree is food for the ants. The ants would need an enzyme called invertase to break up the complex sucrose in the nectar for easy digestion.

But lead researcher Martin Heil found that the Acacia ants lacked invertase. The tree secretes this enzyme as well, so in a sense providing ants with the sugars and the enzymes to digest them. When Heil looked at young ant larvae, they had invertase. How did this enzyme disappear then in adult ants? Well, it turns out that the acacia tree secretes another enzyme that kills the ants' invertase, making them slave to its own nectar! 

Amazing, how far some species go to exploit a mutual relationship, isn't it! 

Courtesy National Geographic, livescience