Parasol ant, parasol ant, how does your garden grow?

A lone leaf-cutter ant. Photo via Thinkstock.

A lone leaf-​​cutter ant. Photo via Thinkstock.

Yes­terday I met biology pro­fessor and insect enthu­siast Rebecca Rosen­gaus to dis­cuss a new paper on the horizon about ant immu­nity. It was a great con­ver­sa­tion and I’ve never been so enrap­tured by a con­ver­sa­tion about bugs (although, I think bugs isn’t actu­ally the cor­rect term…)

In response to my ques­tions about why anyone should care about ant immu­nity in the first place, Rosen­gaus said “because they’re awe­some!” and then pro­ceeded to give me sev­eral exam­ples of why that is so. Number one example: The total bio­mass of ants makes up 15 to 20 per­cent of the total animal bio­mass on. the. planet.

This fact got the old wheels turning in my brain. If ants take up so much phys­ical space, I con­sid­ered, they must have a pretty big impact on the overall eco­log­ical system, right? Rosen­gaus agreed and told me a fan­tastic story of a par­tic­ular type of ant in Panama, which, like all wood eating insects, serves an impor­tant eco­log­ical role of replen­ishing the nutri­ents of plant matter back into the earth.

In the case of the Pana­manian parasol ants, as Rosen­gaus called them, mil­lions of the tiny insects live together in a single nest per­forming agri­cul­ture, con­stantly tending to their “fungus-​​growing garden.”

Here’s how it works: Worker ants come out of the nest and go for­aging for a good tree. They cut out little pieces of the leaves, then carry them back to their nest, sus­pended like a parasol over their heads (hence the name). Back at the nest, they pass the leaf off to the next ant, whose job is to chomp, mush, and crumble the leaf into a pulp. This pulp gets passed to the next ant in line, who lays it del­i­cately on the garden.

And what does the fungus do? It feeds the ants!!! Bril­liant little arthro­pods, right?!