Gayil Nalls, Ph.D.

Gayil Nalls Ph.D.

Sensoria

Like Us, They Kill and Consume. But Could They Save Us?

We are just discovering ants' unique abilities.

Posted Jun 29, 2017

“Karl Marx was right, socialism works,” Harvard biologist E. O. Wilson has said. “It is just that he had the wrong species."

Wilson, an expert on ants, defined them as eusocial—like humans, a species with the highest level of social organization—because of the characteristics he observed. Their colonies consist of overlapping generations, they demonstrate cooperative behavior in caring for their young, and they divide labor and allocate resources to benefit the group.

Ants communicate via scent with an olfactory system that is ultimately more sophisticated than that of humans. Their sense of smell is central to their life, with all their functional and behavioral actions depending on it. And as you might guess from watching them touch when they pass each other, their olfactory organs are located in their antennae, which have more than 400 odor receptors that characterize aromatic compounds. Due to the numbers of odorant receptors, their odor-sensing ability is acute, allowing them to get important social information from the subtle odor of other ants. It can be said that they speak a nuanced chemical language, and because of this, scientists surmise that is was their powerful olfactory capacity that supported kin altruism, enabling them to evolve such advanced colonial organization. 

Black carpenter ants spend a lot of time looking for food, mostly at night, leaving an odor map as they go. They are able to detect odors at a long range and stop when scouting to sense for olfactory clues. They are omnivores and eat other insects regularly, observable in this video of the wingless workers eating a fly. Their olfactory system also provides their sense of taste by chemoreception.

It is likely that they will take the food back to the nest and regurgitate it to feed other nest members. This communal sharing of regurgitated material has been found to pass on antimicrobial properties that contribute to their larger social immunity. 

One of the staples of the carpenter ant’s diet is a substance secreted by aphids called honey dew, which they obtain from the insect by milking it, much like the way humans milk other species without harming them. Carpenter ants are also known to attack large insects en masse, preferring ones that feed on plant sugars. They do this by swarming them and disassembling them with their jaws.

E.O. Wilson and Bert Hoelldobler once wrote that, “When combined, all ants in the world taken together weigh about as much as all human beings.” However, an ant individually weighs between only one and five mg, and we, individually, weigh a million times that, and we have stepped on them and disrupted them for millennia. It is not yet known if human odors trigger a stress response in ants, but when an ant is stepped on, their smashed scent glands release all of their communicating pheromone substances at once. It is the alarm odor that is most volatile, moving far and quickly, transmitting the warning to other ants.

Linda Buck, who was co-awarded the 2004 Nobel Prize in Physiology or Medicine for the discovery of olfactory receptors, has since unraveled some of the neurons activated in instinctive fear response by a predator’s scent. Volatile predator odors can trigger reactions from mild distress or anxiety to full-blown fight or flight responses. Like humans, ants have a stress response system with hard-wired reactions to olfactory stimulus, and it is known that they produce a stress pheromone to warn other ants of danger. Though not comparable to human feelings, some researchers think ants’ behavioral responses can be interpreted as emotions.

The queen carpenter ant, which is thought to live a decade or more, as opposed to the single year most ants live, produces all the fertilized eggs, individuals she will influence by her pheromones. Researchers at Vanderbilt University are just now determining the role genetics play in the ant’s social order. But that doesn’t change the fact that when the queen dies, so does the colony.

Just in case you were wondering why you should know more about ants, other than, perhaps, how to destroy their pheromone trails to keep them out of your kitchen, ponder this:

In 2014, Ronald Dorn, a professor of geology at Arizona State University in Tempe, published a startling study in the journal Geology that concluded that ants may be Earth’s most powerful biological mitigator of Climate Change. Certain species help cool the planet by trapping CO2 (the greenhouse gas that human activity produces) from the atmosphere in limestone during a process of breaking down minerals to secrete calcium carbonate (limestone).

Dorn was not looking to study ants when he made this discovery, but suspects that the tremendous volumes of ants on earth work together to remove carbon dioxide from the atmosphere. Additional research will be pursued to see whether or not bacteria or fungi play a role in this unique ability.

We are just beginning to understand the unheralded capacity of ants to cool the planet.

Article and Video © 2017 Gayil Nalls, All rights reserved.

Gayil Nalls, Ph.D., is published online and in print, most recently with her post for Nautilus "What It’s Like to Be an Ant" and her essay "The Politics of Perfumed Objects" in Martin Hegel and Matthias Wagner K's "For the deeper meaning- fragrance as medium in art, design and communication" (Germany, Spielbein Publishers, 2016). Follow her @olfacticinkblot and @themassinglab

References

"Ant Chemosensory Biology." Ant Chemosensory Biology. Ed. Laurence J. Zwiebel. Vanderbilt University, n.d. Web. 25 May 2017. http://www.vanderbilt.edu/zwiebellab/Ant_Chemosensory_Biology.html

Fujiwara-Tsujii, Nao, et al. "Behavioral responses to the alarm pheromone of the ant Camponotus obscuripes (Hymenoptera: Formicidae)." Zoological science 23.4 (2006): 353-358.

Hamilton, C; Lejeune, B. T.; Rosengaus, R. B. (2011). "Trophallaxis and Prophylaxis: Social Immunity in the Carpenter Ant Camponotus Pennsylvanicus". Biology Letters. 7 (1): 89–92. PMC 3030872  PMID 20591850. doi:10.1098/rsbl.2010.0466.

Hölldobler, Bert, and Wilson, Edward O.. The Ants. Cambridge: Harvard University Press, 1990. Print.

Perez, Margot, Martin Giurfa, and Patrizia D'ettorre. "The Scent of Mixtures: Rules of Odour Processing in Ants." Scientific Reports 5.1 (2015). Web. https://www.nature.com/articles/srep08659

Wade, Nicholas (May 12, 1998). "Scientist at Work: Edward O. Wilson; From Ants to Ethics: A Biologist Dreams Of Unity of Knowledge". The New York Times. http://www.nytimes.com/1998/05/12/science/scientist-work-edward-o-wilson-ants-ethics-biologist-dreams-unity-knowledge.html

Dorn, Ronald I. "Ants as a powerful biotic agent of olivine and plagioclase dissolution." Geology 42.9 (2014): 771-774.