Ants living in Cecropia trees quickly repair wounds to their host

Unrelenting swarms of Azteca ants fiercely guard the Cecropia trees they live in throughout neotropical forests. Recently, a bored teenager found that there’s something more to the ant’s relationship with the tree than the fearsome stinging and biting of herbivores and clumsy humans. 

Wandering through the forest in Panama, a high school student shot a hole through a Cecropia tree with a clay ball fired from a slingshot. Returning to the scene of the crime the next day, he noticed that the ants living inside the Cecropia had neatly patched up the slingshot hole. 

This intriguing discovery inspired five high school students to participate in the Smithsonian Tropical Research Institute’s (STRI) volunteer program. 

“Some species of Azteca ants live in a permanent symbiosis with Cecropia plants: these mutualistic ants aggressively defend their host plants against herbivores, and in exchange the plants provide them with food and shelter,” wrote the researchers. 

“The ants prevent damage to their hosts’ leaves, because the ants’ food is produced at the base of the petioles and the undersides of the leaves. Worker ants also open and maintain small entrance holes in each internode that they occupy.”

The teens set out to determine what happens when damage to the Cecropia tree compromises the ant’s shelter instead of its food production. Working with STRI staff scientist William T. Wcislo, the students drilled holes into Cecropia trees and documented repair by the ants. 

The research revealed that as soon as holes were completed, ants were on the job repairing them. Within two and a half hours, significant progress was made and the work was often finished within twenty four hours. 

“I was totally surprised by the results,” said Wcislo. “And I was impressed by how they developed a simple way to test the idea that ants repair damage to their home.”

Anteaters often visit Cecropia trees and sometimes punch holes in branches with their sharp claws. The research group speculates that this is how the ants evolved their repairing behavior. 

The research leaves some questions remaining though. Some of the ants did not repair holes in their homes. The factors of why or why not the repairs were made remain unclear and a good topic for future research.

The study is published in the Journal of Hymenoptera Research.

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By Zach Fitzner, Earth.com Staff Writer