• Philidris nagasau, a species in Fiji, has created an ecosystem using a technique that has lasted for millenia. (Supplied)
Ants are fascinating; they occur in almost all ecosystems and can communicate effectively between each other. New research shows they're leaders in agriculture too, using a technique that has lasted for millennia.
By
Sophie Verass

23 Nov 2016 - 2:39 PM  UPDATED 23 Nov 2016 - 3:19 PM

Ants have always been known to be industrious creatures, but new research has revealed that a particular species of ant – the Philidris nagasau in Fiji – has been outperforming humans in some areas.

An analysis of the behavior of a Fijian ant which actively cultivates plants and then inhabits them, suggest that ants have been farming plants for millions of years – long before human agriculture.

This is the first case of obligatory agriculture by ants found, whereby native ants are discovered to actively farm at least six species of an epiphytic plant on the Fijian Islands.

These epiphytic plants or Squamellaria grow above ground, through the support of another plant or tree trunk. Being above the ground means they do not have access to soil for rich nutrients. However, German academics Guillaume Chomicki and Susanne Renner have discovered that the local Fijian ants help these plants thrive by forming a hollow chamber to access in-and-out, and intentionally ‘do their business’ inside the young plant to fertilize it, like a purpose-built composting outhouse for the community.

More interestingly, these are plants that the ants planted themselves. The ants are recorded to collect seeds from another epiphytic plant’s fruits, which they then insert into the cracks of a host tree. Once seedlings form, the ants will then commence the fertilising process and the plant’s chambers will start to grow to a substantial point where the ants will successfully have made a permanent shelter and nesting space for their colonies.

One of the study’s authors, Chomicki says that this finding highlights how these ants and plants are interdependent and one cannot survive without the other; the ants need protection and shelter from the plant and the plant needs to be fed and nurtured by the ants.

“I think that it adds one more aspect to the extraordinary biology of ants,” Chomicki told SBS Science. “They are already well-known to farm mealy bugs and fungi, but the diversity of their interactions with their biotic environment plays a central role in their ecological success on Earth.”

“They are already well-known to farm mealy bugs and fungi, but the diversity of their interactions with their biotic environment plays a central role in their ecological success on Earth.”

Other ants that form so-called ‘ant-gardens’ in the Neotropics have also been known to collect the seeds of epiphytes. However unlike the Fijian ant, they do not cultivate their plants by using their bodily waste as fertiliser. Generally, the types of epiphytes used can also flourish without the ants’ production which is not the can for this unique species.

Chomicki and Renner determine that the evolutionary history of both, the ants and plants (the plants having developed specific adaptation for bark anchoring and the ants ingrained planting behavior) suggests that this farming behavior began approximately three million years ago. Humans, who pride ourselves on our domestication of plants and agricultural abilities, on the otherhand, would have still been in our “Lucy” phase.

This paper was a part of Chomicki’s PhD research at the University of Munich and he aims to continue working on this topic since its completion.

“Since my earliest childhood, I have been fascinated by plants. I got into ants later once I learned about their interesting interactions with plant life,” he told SBS Science.

“All the ants on earth are heavier than all humans; They occur in almost all ecosystems, some species form colonies that spread over thousands of kilometres, ants form complex societies and communicate effectively between each other and they detain a lot of records.”

Chomicki admits he took a risk conducting his assignment in Fiji,

“The idea of going to Fiji was a bit of a gamble really! The plant group to which these ant-plants belong to is scattered all around South-East Asia - in Indonesia but, most of the diversity is in New Guinea. Doing fieldwork in Papua New Guinea is both dangerous and difficult in terms of getting permits, so I decided to go to Fiji instead where they were apparently three endemic species. At the time, I pretty much guessed that something exciting was going on there and thought that in the worst case scenario it would be a nice holiday!”

Fortunately for Chomicki, he had a breaking discovery that will contribute to the world having a better understanding of animal science and behavioural ecology.

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