Fourmis,
antibiotiques
et nous

Depuis des millions
d’années, les fourmis
Attini ont cultivé des
antibiotiques
efficaces contre des
bactéries que même
nos plus fortes
drogues ne sont plus
capables de
contrôler; l’ironie,
c’est qu’on les
remercie en
détruisant leur habitat
dans les forêts
pluviales. 

À chaque jour, de
telles espèces
disparraissent à
jamais et apportent
avec elles des
millions d’années
de connaissances
accumulées par
l’évolution. 

L’auteur David
Suzuki pense que
"nous pourrions
apprendre quelque
chose de ces petites
créatures concernant
l’importance du
maintien de la
biodiversité et de
"cultiver" de bonnes
relations avec la
nature. Ces
connaissances
pourraient mener
à une meilleure
compréhension,
surtout en matière
d’agriculture et de
médecine."

Ants, antibiotics and us

David Suzuki
David Suzuki Foundation
July 14, 1999

he immense complexity of the natural world never ceases to amaze scientists. Just when we think we have something figured out, a new study comes along that shakes the very foundations of our previous assumptions.

(photo: Leafcutter Ants website)

========= Attini Ants =========

Take the little world of the South American leaf-cutter ant, for example. A recent study by Canadian scientists in the Amazon has found that the relationship between ants of the group Attini and the mushrooms they grow for food is much more complicated than originally believed. The study results, published in the journal Nature, highlight the importance of diversity and symbiosis (a partnership in nature where organisms mutually depend on one-another) as survival mechanisms mechanisms that human activities are steadily eroding.

Millions of years ago, ancestors of the Attini ants quit hunting and gathering for food to become farmers. It was a profound evolutionary move and it worked. Today, the Attini are a highly successful bunch, with some colonies numbering more than eight million members.

The Attini practice organic agriculture, cutting leaves and chewing them into a pulp that they use as a compost in which to grow fungal crops like mushrooms. This symbiotic relationship has been well-documented, but until earlier this year, scientists thought the partnership ended there. New evidence now shows that there are actually two other organisms involved in the relationship a weed fungus and an antibiotic-producing bacterium.

  ====== Author: David Suzuki   ======

(photo: David Suzuki Foundation)

Various species of the weed fungus are found in every Attini garden, and scientists haven't found them anywhere else, so they seem to rely entirely on the ants for their survival. A parasite, the weed fungus can multiply quickly and overcome the ant crop, but in healthy gardens the fungus is kept at bay by a bacterium on the ants' bodies that produces antibiotics. These antibiotics are key to the survival of the colony.

Antibiotics are also extremely important to humans to protect us from a variety of disease-causing organisms. Unfortunately, in spite of our best efforts, these organisms have continually one-upped humanity by developing resistance to our antibiotics. Even our strongest drugs such as vancomycin are now powerless against some bacteria. Yet somehow the lowly Attini ants have been cultivating an effective antibiotic that has held-off resistance for nearly 50 million years!

One way the ants may have managed to stay a step ahead of the weed fungus is by growing a variety of different mushrooms. Rather than continuously cultivating the same mushrooms, the ants occasionally replace their crops with outside variants, derived either from the wild or from other ant colonies. This strategy of diversity seems to have worked in favour of the ants best long-term interests.

Humans would do well to keep this in mind for our own long-term self interests. No doubt we could learn something from these tiny creatures about the importance of maintaining biodiversity and cultivating relationships with nature. These insights could lead to greater understanding in the fields of agriculture and medicine.

Unfortunately, the tropical rainforests in which the Attini live, home to the greatest diversity of life on the planet, are being cut down and burned at an alarming rate. Every day, species like the Attini disappear forever, taking with them millions of years of evolutionary knowledge. It is a sad irony that humans are so blindly destroying the very things these ants could teach us about.

* previously published in column: Science Matters