Why did fierce Aztec ants heal tree injuries in less than 24 hours?

What's new here is the observation that insects repair damage to their tree friends if that shelter is threatened.

One afternoon, during the early days of the COVID-19 epidemic in Panama, a bored teenager fired clay balls from his slingshot to accidentally create “wounds” in and out holes in the trunk of a Cecropia tree. Also known as the "ant plant" trees, it is famous for its cooperation with the fierce Aztec ants. Trees provide shelter and food for the ants, and in return the ants defend their leaves against herbivores.

When high school student Alex Weslow shoots a 9-millimeter clay ball with his slingshot, leaving wounds in the tree; Not expecting what had happened, the ants ran to the wound area and started grafting it. As it stated in the report of the site "Science Alert" (Science Alert) it is within two hours and a half the size of the hole has been reduced dramatically.

The accidental slingshot strike of a scropia tree in Panama - known as a scrotum - led to a surprising discovery: the willingness of the Aztec ants (Azteca alfari) that live inside these trees to repair damage to their homes in less than 24 hours. This is according to a research paper published on December 30 in the Journal of Hymenoptera Research.

The enthusiasm of high school students led to an important discovery

The quick mending of the wounds left in the trunk of the tree excited Wislow; Which made him do more experiments with 5 of his student friends, so he dug holes in other trees to see how to fix them.

The ants dwelling within those trees repaired the destruction that had occurred over and over again. These experiences were then recorded, written, and published in a research paper, as part of the volunteer program at the Smithsonian Tropical Research Institute.

"I was completely surprised by the results and impressed by the way the students developed a simple way to test the idea that ants repair damage to their homes," says William Weslow, an ethicist at the institute.

A symbiotic or mutually beneficial relationship between Aztec ants and their host trees has already been demonstrated, with the ants doing their best to defend the trees against herbivores, receiving in return nourishing oily secretions from the leaves to eat and harbor inside hollow stems.

What's new here is the observation that insects also repair damage to their tree friends if their shelter is threatened. Based on the new research, this appears to occur most often when the 'brood' (eggs, larvae and pupae) in a colony are at risk.

Repairs are made in these trees by using materials inside the stem of the plant itself, but this did not happen in all cases where holes were made in the tree, only 14 of the other 22 holes drilled in the tree were repaired. Thus understanding the reason for this may be a new topic of research.

Why do ants fix tree injuries?

In their published paper, the researchers write that the reason for the tree hole repair behavior of ants "may be that a hole in the wall exposes the ants' vulnerable immature stages to external pathogens, predators, or changes in other environmental parameters."

After penetrating Sicropia trees, Aztec ants would close some but not all infestations, lending credence to the idea that repairs to the trunk of the tree are more about the welfare of the ants themselves than any benefit to the tree itself.

This is supported by observations made during the experiments, that the ants would clear the brood before beginning the patching task. It is possible that when repairs are not carried out by the ants, it is because the weak members of the colony are not under immediate threat. However, the team cannot rule out the possibility that the tree receives some benefit from this ant behavior, such as antimicrobial secretions around its infestation.

Although slingshot pellets are not usually a problem for cyclopia trees, holes left by the toenails of sloths and anteaters are often a problem, which may be why the ants they host have evolved to behave this way.

"Sometimes fiddling with the sling is a good result," says Alex Weslow, who teaches at the International School in Panama. “This project allowed us to experience first-hand all the complexities behind scientific study. All in all, it was a great learning experience, especially considering the difficulties associated with achieving this due to COVID-19.”