Ants have been regarded as model organisms due to their small size, short generation time, and the lack of guilt researchers feel in manipulating them. What I did to those four species of acacia ants that I studied in depth with Columbia’s EEEB department (ecology, evolution, and environmental biology) in the Laikipia District of central Kenya would be a moral and legal fiasco with most other organisms.
Unlike honey bee attacks, all ant species that occupy the popular Acacia Drepanobulum trees can bite and bite and spray all the chemicals they store in their small abdomens with reckless abandon. These pungent liquids, pheromones, symbolize heterospecific and conspecific aggressive behaviors, meaning that ants engage in civil war as well as international war when threatened.
I posed an obvious threat to these ants. Roaming through a forest of various acacias, I searched for specific color combinations: red-red-black (Crematogaster mimosae) and black-black-red (Crematogaster nigriceps). From half a petri dish, I created a battle arena and disproportionately placed the same species from different trees as well as different species, timing how long it took them to kill each other.
Before the battle, I had to verify that the enemy was indeed the enemy by sending a sample victim into the “home” colony. A tangle of writhing black substituted for passport identification. But beyond smelling enemy pheromones, do varying defense behaviors exist?
I knew the answer was yes even before I began my vicious permutations. I tapped an acacia branch until the ants left the comfort of their enclosed habitat, bulbous brown swollen thorns, to investigate my attack. Positioning the two sides of a petri dish like hinged jaws, I then proceeded to engulf ten samples. If I counted less than ten, I snapped again.
“Pain is temporary,” I reminded myself as ants escaped my gutless plastic monster, rioting on my forearms. I murdered more than I imprisoned. Maimed ants were flicked away for fear of faulty results. Both species bit with equal ferocity and impressive alacrity. They shimmied up to my neck and squeezed down to my toes.
Though I did not have access to a wet lab, I detected the release of defense pheromones. I could not see them in the battle arena but I could smell them on my own skin—an acrid and moldy stench, like mixing wet leaves with used running socks.
Given their retaliation towards me, I expected similar brutality when faced with an intruder ant, which I shoved into a petri dish of its enemies. But for every kind of enemy—C. mimosae of one colony versus C. mimosae of a second colony, C. mimosae versus C. nigriceps, C. nigriceps versus C. mimosae, C. nigriceps of one colony versus C. nigriceps of a second colony—the ants employed a different war tactic. In what can be dubbed an act of brotherly love, the acacia ants exhibited a faster and more frequent heterospecific response than conspecific response. Ants of different species became nothing more than eraser rubbings rolling around the petri dish. Ants of the same species but different colonies were sometimes killed, sometimes pardoned.
In the aftermath of ant war, there was no blood and no guts. A few shriveled black specks like squashed soda cans did nothing to elicit any emotional response. My emotional response came when, after believing my hypothesis to be correct, I ran statistical chi-squared and wilcoxon tests of my data and found that there was too much variance to have conclusive findings. I could spend another day in the field collecting more samples, I could revise my experimental design by grinding up the different species into a PETA-disaster-paste and covering the ants in enemy pheromones, or I could admit my lack of dedication and stare at the less belligerent drongo birds.
That night, kicking off my brown coated clothing, a few ants skittered off into the corners of my tent. Briefly checking for ticks and sunburn and remembering with surprise to swallow a malaria pill, I immediately fell asleep. The dreams of a researcher sting with the bites of Crematogaster acacia ants.
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