Ants living in trees, cohabitating with a complex community of fungi.

“Ants and Their Symbiotic Microbes Living in Trees

Ants are known for their social organization and division of labor, but the bacteria inside their nests might also play a role in their success. Azteca ants living in Cecropia trees (dioecious trees native to the Neotropics) create unique structures called ‘patches’ inside their host plants. These patches are not just homes for ants but also for bacteria, fungi, and nematodes, and are vital for the development of the ant colonies. However, detailed knowledge about the composition and consistency of microbial communities throughout the life of an ant colony has been lacking. What’s really going on inside these trees?”

Bacterial diversity in arboreal ant nesting spaces is linked to colony developmental stage

“Analyzing Methods: Investigating the Symbiotic Relationship between Azteca Ants and Cecropia Trees

In this study, we chose the symbiotic relationship between Azteca ants and Cecropia trees as our model system to examine the dynamics of bacterial communities throughout the lifespan of ant colonies. The Azteca ants live in the hollow stems of Cecropia (apparently called domatia) and form numerous distinct patches alongside specific Chaetochloria bacteria and bacterivorous nematodes. In early colony stages, the queen ant creates the initial patches, and later, worker ants form and maintain new patches throughout the plant. In this research, we amplified and sequenced the 16S rRNA gene from patches at three developmental stages of Azteca ants. rRNA, a part of the ribosome present in all life forms except viruses, is a crucial molecule in protein synthesis. Known for its relatively slow evolutionary rate and high homology at the species level, it’s a key tool in distinguishing species. So, it’s like sorting them by species, right?”

“Results & Discussion: Changes in Bacteria During the Developmental Stages of Ant Colonies

The developmental stages of ant colonies were defined as early, young, and established colonies. Bacteria accounted for 99.9% of the total readings in these patches. Patches in the early and young colonies showed lower bacterial diversity compared to those in mature colonies, with no specific community composition unique to the ant species observed. Initially, there was a bustling diversity of fungi, which later seemed to mature into a stable colony. Ultimately, the microbiome shifted to one specific to the ants, suggesting that each ant might have its own ‘preferred microbiome.’

The patches created by ants are hypothesized to contain bacteria resistant to pathogens and to provide nutrients to the ant larvae. This is not just beneficial for the ants but might also be advantageous for the symbiotic plants. Quite a fascinating partnership, isn’t it?”

“The Coevolution of Ants and Bacteria Inside Trees

As ant colonies develop, the composition of their bacterial communities changes. From the early patches to the young and then to the established stages, bacterial diversity notably increased. Also, the relative abundance of certain taxa either increased or decreased (meaning the presence of fungi changed). This research is crucial for understanding the coevolution of ants and bacteria and how their symbiotic relationship within trees contributes to the development of ant colonies. It’s fascinating to think about such dynamic changes happening inside a tree when you casually look up at it.”

“Considering the Industrial Value

The industrial value of this study is still a bit of a mystery, but the possibilities are diverse. While this paper doesn’t delve into the formation process of the patches, the idea of altering the inside of plants is incredibly intriguing. Modern plant transformation techniques use a bacterium called Agrobacterium, discovered in crown galls (tumor-like formations) on cherry trees, to introduce its own genes into plants. Rhizobia bacteria induce the formation of nodules in legume plants. There are numerous examples of organisms affecting plants, each leading to useful technologies. As the symbiotic process of ants and fungi is further unraveled, we might also understand mechanisms that alter the structure inside trees. This could potentially lead to the induction of useful traits or the discovery of new materials.”