By Anna Berardi

Apparently, freeloading relatives don’t just exist in the human world. Some ants have to contend with mooching cousins, too.

A recent discovery of a new ant species sheds light on rare parasitic ants — the kind that invade other ant colonies and assume the identity of their unsuspecting host.

Nature.org spoke with Zachary Prusak, entomologist and Nature Conservancy fire manager, and Mark Deyrup, biologist at Archbold Biological Station, about their discovery of Solenopsis enigmatica on the remote island of Dominica in the West Indies.

Nature.org: How does one discover an ant? Do you go looking for it or does it find you?

Zachary Prusak: New ant species can be discovered in both the remote jungles of Madagascar and on urban neighborhood fences! For this trip to Dominica, Mark and I set out to document as much of the island’s ant species as we could in a brief visit.

We suspected that we might uncover new species, simply because there are so many microhabitats to sample, like in tree canopies and leaf litter. Each one has its own unique complex of ants.
 

Nature.org: How did you know this ant was special? 
 
Zachary Prusak: Mark and I were looking through a rotten log and we noticed a tiny yellow-brown ant within a colony of common, medium-sized, dark-brown ants.

We knew of some rare examples of parasitic ant species that live very secretive lives. It turns out that Solenopsis enigmatica is similar to another ant known only from one specimen collected in Florida.

Very little is known about parasitic ants, except that they often spend much of their life cycles living with other ant species. Think of a freeloading relative who won’t leave.
 

Nature.org: Is parasitism unusual in ants? How rare is this and what makes parasitic ants so unique in the insect world? 

Zachary Prusak: Parasitism in ants is not the norm, although there may be more discoveries like this in the ant realm.

Parasitism ranges from "slave raiding ants" that need to steal worker ants from other colonies in order to have them do the work the raiders cannot do, to "temporary social parasites" whose queens sneak into nests and replace the host queen.

What makes them unique in the ant world is that this form of social structure is not common among ants, and infrequently encountered.
 

Nature.org: Since these ants are a different species—even a different color—than their host, how do they go unnoticed?

Zachary Prusak: Based on what we know of other parasitic ants, Solenopsis enigmatica must have the ability to chemically disguise itself in order to gain entrance into the host colony.

While humans are very visual creatures, most ants live in a very dark underground world. Therefore, their communication methods rely more on touch and smell. 
 

Nature.org: Solenopsis enigmatica is a very interesting name. How did you choose it?

Zachary Prusak: The names of new species are typically derived from Latin or Greek words that describe specific characteristics, but they also can refer to a place or a person.

The genus “Solenopsis” — meaning “pipe face” — was described in 1840 and refers to fire ants (or red ants). For this new ant, Mark came up with the name “enigmatica” — which means “mystery” — to reflect how little we know of this new species and the need for further exploration into its life history.
 

Nature.org: What's the process once you have discovered a new species?

Zachary Prusak: Finding the people to identify them is the other big task, since many insects are very hard to identify. Once you find one, the specialist will examine the ant and compare it to similar species.

A scientific description of the new species is prepared, presenting the physical characteristics that set it apart from other species within that group. Then the description is published in a scientific journal, making the name official. For us, the process took about two years.
 

Nature.org: You manage controlled burns in Florida for The Nature Conservancy. Where do ants fit in?

Zachary Prusak: From a very early age, I was always fascinated with ants. Instead of fish, I would fill up ten-gallon aquarium tanks with dirt and ants. This love of ants led to an interest in biology and then to a master’s degree in ant diversity.

My work with fire implementation and fire ecology fits well with ants, since there are many ant/plant relationships around the world that involve fire.
 

Nature.org: Why should people care about ants?

Zachary Prusak: To be committed to protecting nature and preserving life, we must learn more about ‘the little things that run the world,’ as E.O. Wilson refers to them. The sheer number of bugs that thrive under our feet is impressive.

Decomposition and pollination are just a few of the ways insects are critical to people and nature. The rich diversity of ants offers us much to learn and much to preserve.

By protecting conservation sites around the world, we can insure that these fascinating ants are available for future generations to examine — and make their own discoveries.

 
Anna Berardi is a Nature Conservancy marketing specialist/writer for Florida.

Nature picture credits (top to bottom):  Photos © P. E. Skelley, FDACS-DPI (Solenopsis Enigmatica); © Anna Berardi/TNC (Zachary Prusak); © P. E. Skelley, FDACS-DPI (Solenopsis Enigmatica)