Pest Control III:

Fire Ants

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Kingdom – Animalia

Phylum – Arthropoda

Class – Insecta

Order – Hymenoptera (membrane winged)

Family – Formicidae (ants)

Genus – Solenopsis

Species – invicta

    Every year thirty to sixty percent of the people living in certain parts of the American South get a painful reminder of the proposition that ants evolved from wasps. Those people have a too-close encounter with Solenopsis invicta, commonly called fire ants (because being stung by one feels much like being burned). The Food and Drug Administration estimates that medical treatment, direct damages, and the cost of control efforts cost America roughly five billion dollars annually plus 750 million dollars in veterinary bills for injured animals along with the loss of livestock and crops. The red imported fire ant is a belligerent little bugger that does a lot of damage and its not even native fo North America, so we can exterminate it with a clear conscience.

    The most effective way, indeed the only way, to exterminate an ant colony employs anything that kills the queen. Because the queen is the only member of the colony that reproduces, the death of the queen leads to the end of the colony when the life spans of its members expire. Of course, the queen lies deep within the nest for her safety: the ants would not have existed for over one hundred million years if that practice had not evolved early in their existence. We thus face the question of How do we get to the queen?

    There is an odd phenomenon that may help us. Around Mount Nyiragongo, a volcano which rises above the city of Goma on the north end of Lake Kivu in the Democratic Republic of the Congo (formerly Zaire), just west of Rwanda, swales fill with carbon dioxide, which seeps out of the ground around the volcano, and turns the swales into deadly traps. Called muzuku (muh-ZOO-koo), the traps are so insidious that even today people wander into them, pass out, and die from lack of oxygen. This is what we need for our ant killers.

    In concept it’s simple. Turning an ant nest into a muzuku consists simply of erecting a sleeve around the entrance to the nest and then pouring into it carbon dioxide or liquid nitrogen. The denser gas, either carbon dioxide or cold nitrogen, sinks into the nest, displacing the lighter, oxygen-laden air and killing the ants by asphyxiation. Soon the inert gas reaches the queen’s chamber and the colony dies.

    We know, of course, that anyone who attempts to carry out the act of turning a fire ant nest into a muzuku will be attacked by an army of enraged ants. Unless the exterminators are willing to walk around wearing what are, in essence, spacesuits, this is no job for humans: it’s properly a job for robots.

    We will need two kinds of robots for this project – scouts and matadors. The scouts will seek out the ant colonies and survey them and the matadors (Spanish for killers) will carry out the actual extermination. Because their part of the job is the harder one, the scouts will outnumber the matadors.

    A scout might resemble a tarantula the size of a border collie. Such arachniform robots will be easier to produce than will mammaliform robots. Wandering over the landscape, the scout will power itself by ingesting organic detritus, which it feeds into a stomach whose lining consists of an Omniphage being operated as a rather elaborate fuel cell. Combining atmospheric oxygen with organic material from dead leaves and road kill, the Omniphage will supply on-demand electric power to the scout’s motors, sensors, and computer brain.

    Perhaps brightly colored so that they won’t startle people, the scouts will spread out over areas where fire ants reside. Each scout will have in its computer brain a set of neural nets that will receive optical inputs from the robot’s eyes and recognize Solenopsis invicta, clearly enough to distinguish it from other ants. Once a scout finds a fire ant, it follows the ant back to its nest. It may also alert other, nearby scouts so that, together, they improve their chances of finding the nest quickly.

    Sooner or later the scout finds an entrance to the nest. Usually it will be hidden under something, such as a rotting log or some other overhanging object and the scout will make note of that arrangement. Next the scout will insert probes into the ground and use pulses of sound to explore and to map the hollow spaces that represent the chambers of the ants’ nest. With all of the relevant information in mind, the scout then calls a matador.

    The matador resembles a giant beetle, largely due to the tank on its back. The tank carries liquid nitrogen or carbon dioxide, either compressed or in the form of dry ice. When the matador arrives at the site it, perhaps with the help of the scout, removes the overhanging object to expose the entrance to the nest. Under vicious attack by the ants, the matador will place a cylindrical sleeve of plastic sheet or sheet metal over the entrance area of the nest, with the entrance hole itself near its center, and push the sleeve a short distance into the soil to close up any gaps between the sleeve and the ground. Then the matador will feed the inert gas into the sleeve. Using the scout’s map of the nest and a theory derived from laboratory experiments on chamber and tunnel arrangements, the matador will estimate how long it must put gas into the nest to be reasonably certain that it got the queen. When it has finished its task, it removes the sleeve and goes to its next assignment.

    Eventually the ants outside the nest will calm down and return to business as usual. Those that re-enter the nest will die in the inert atmosphere. Those that don’t re-enter the nest will live longer, but eventually they, too, will die. The colony will be gone.

    It will take several decades, at minimum, for the robots to eliminate Solenopsis invicta from North America, but robots are patient. They don’t get bored and they don’t get distracted. They will get the job done and the American ecosystem can recover from the damage that the fire ants have inflicted upon it.


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