Fix repaired holes: A tropical species of ant repairs damage to trees with which it lives in a partnership, shows a study carried out in part by student researchers. At the beginning there were random bullet holes that one of the young authors gave an “ant tree” with his slingshot. Such wounds are usually closed by the inhabitants of the plants within 24 hours, documented the subsequent investigation with the participation of a scientist.
Win-win communities across species boundaries: A particularly interesting example of symbioses in nature are the intimate relationships between the tropical Cecropia trees and ants of the Azteca genus. In the course of evolution, both partners have adapted intensively to one another, as earlier studies have already shown. The cecropia trees offer the insect colonies a safe home in their hollow trunks and even provide them with food. The shrub-like plants form nutrient fluids in certain places. In return, the ants take on the role of bodyguards for their home plants: they keep pests away.
The new aspect of this relationship system happened to be noticed by a student attending the International School of Panama in Panama City. To pass the time in the early phase of the Covid-19 pandemic, he shot small clay balls with a slingshot into the local botany. When checking the results, he found that he had missed holes around nine millimeters wide in the rather soft trunks of Cecropia trees. By chance he took another look at these wounds the next day and made a discovery: the holes had apparently been closed by the ants that inhabit the plants.
A student research project is born
A research project developed from this observation as part of a volunteer program at the Smithsonian Tropical Research Institute (STRI) in Panama City: A team of five high school students with the support of STRI scientist William Wcislo investigated ant behavior more closely through experiments. To do this, the young researchers bored holes in Cecropia trees and documented the ants’ reactions to the damage.
It turned out that in most cases the Azteca alfari crawlers immediately ran to the wounds and began to mend them. As a result, the size of the holes was already reduced considerably within 2.5 hours and they were often completely closed within 24 hours. For the repairs, the ants use fiber material that can be found in the plant stem itself, as well as a sticky substance that is probably at least partially made up of sap. As the team sums up, it becomes clear that the Azteca ants not only keep threats away from their host plants – they also actively repair damage if injuries occur.
A symbiotic behavior?
Other living beings are also known to repair damage to their homes. “But in this case we show that a living structure can be repaired by the ants using plant material from inside the trunk,” the authors point out. The team suspects, however, that the ants are primarily interested in self-interest: they probably want to prevent the opening of a threat to their brood inside the hollow trunks. An indication of this was the observation that the ants evacuated their offspring from the areas affected by the drilling.
However, it is also possible that the ants excrete antimicrobial glandular secretions during their repair work, which could thus support the healing process of the plant wound. “If this were the case, the Cecropia trees would also benefit from the behavior of the ants in this case,” the team writes. But apart from slingshot shots, what could lead to holes in the trunks of the plants? The researchers see damage caused by sloths, which often roam cecropia trees, as a possible natural cause: With their pointed claws, they could cause holes in the soft trunks, according to the explanation.
So far, however, it remains unclear why not all ant colonies carefully patched up the damage to their host plants. Because in some cases the wounds were only poorly cared for or the repair was not carried out at all, according to the observations. “Understanding what factors cause ants to take certain actions could be the subject of future research by potentially budding scientists,” writes the Smithsonian Tropical Research Institute.
Source: Smithsonian Tropical Research Institute, article: Journal of Hymenoptera Research, doi 10.3897 / yr. 88.75855