Germany for a Summer: My time with the ants

My summer research began with me driving down to the tiny town of Rensselaerville, NY in search of ants.  There, at the idyllic Huyck Nature Preserve, I met up with my advisor and some of my labmates, who had arrived a week earlier from the Johannes Gutenberg Universitat in Mainz,Germany. Each day we would hike out into the woods of the preserve and search for black fungus-covered felled branches,  which our species of interest, Temnothorax longispinosus, loves to inhabit. After collecting armloads of the sticks, we would sit down and crack open the sticks with pocket knives. Upon finding a T. longispinosus colony crawling around inside a stick, we’d tap the colony out into plastic bags for storage.

Searching for T. longispinosus out in the field.

Searching for T. longispinosus out in the field.

Just a fraction of the 1000 colonies we collected at the Huyck.

Just a fraction of the 1000 colonies we collected at the Huyck.

After collecting close to 1000 colonies, we stuffed the bags into several suitcases (amazingly, the colonies all survived) and flew across the Atlantic. Upon arriving at the university with our tens of thousands of guests, we began a several week process of unpacking, cataloguing, and feeding the colonies in preparation for our experiments–the downside of using organisms collected in the field! I began my project by labelling my ants with colored wire based on their caste. T. longispinosus are particularly small ants, so it was quite a challenge to slip loops of colored wire around their abdomens–the first few took about 45mins each. But after a few days, I was able to “wire” over 30 ants per hour.

Deep in focus while wiring ants.

Deep in focus while wiring ants.

Then at last came the actual experiment. I fed half of my 40 colonies dsRNA fragments designed to knock down expression of a gene hypothesized to be essential for maintenance of the ants’ circadian rhythms. No one had looked at this gene in ants before, only a Drosophila homologue. My advisor and I were specifically curious in what effect knocking down this gene would have on foraging behavior, since an earlier expression analysis had found the gene to be overexpressed in foragers relative to brood carers. For comparison’s sake, we instead fed nonsense RNA to the other half of the colonies.

 

After a week-long knockdown period, I began videorecording colony behavior. Colonies were placed in arenas and filmed for 24 hours, with alternating light-dark conditions in the filming area to simulate day and night. Ants can’t see red light, so we used red LEDs to illuminate the arenas without disrupting the ants’ perception of day and night.

 

I then took to analyzing foraging behavior in the videorecordings. With 480 hours of footage to review, this was quite the task. But I was able to finish just in the nick of time, obtaining the final results a day in a half before I was scheduled to present my findings to the lab.

 

What did I find? Somewhat unsurprisingly, I found that  knocking down this gene indeed appears to disrupt the circadian rhythm of foragers, causing them to abandon their normal diurnal foraging schedule and forage equally throughout the day and night. The gene does not, however, appear to more generally affect the decision to forage, since we found no difference between control and knockdown colonies in foraging levels over the entire 24hr period.

 

With confirmation that this gene is essential for the normal circadian rhythm (at least in foragers) in T. longispinosus, the door is now open for some deeper research questions. Is this gene’s circadian-related function limited to foraging, or does it affect activity in general, for all castes of ants? And does the ant circadian rhythm respond to perception of time of day, light conditions, or both?
Working on this project in the context of a different culture made the experience especially stimulating for me. It was difficult adapting to the new environment at times, but the challenge made for a good deal of personal growth. I’m returning to Haverford feeling rejuvenated (though jet-lagged!), excited to dig into my senior research. No more ants for me, probably, but I appreciated the opportunity to dip my toes into research with a behavioral focus. Thanks so much to the KINSC Summer Scholars program for funding me this summer.

The view of Mainz across the Rhine.

The view of Mainz across the Rhine.