The Living Dead: Zombie Insects
The zombie phenomenon is most applicable to human beings. As Merriam-Webster online dictionary states, a zombie is “a person held to resemble the so-called walking dead; a person markedly strange in appearance or behavior.” Of course there are many other ways to explain the zombie phenomenon, but this automaton aspect better explains nature’s living dead. As we know, or at least have observed in American culture, the zombie phenomenon focuses on humanity, but this leaves concern for how animals are affected or what becomes of them. Keeping this in mind, I think this is an important concept to consider; however, I also think that we tend to overlook how insects may contribute or be affected by the zombie phenomenon. In fact, insects have been implementing processes of zombification through parasitism as part of their life cycles. Parasites are defined as “an organism living in, with, or on another organism in parasitism; something that resembles a biological parasite in dependence on something else for existence or support without making a useful or adequate return” (Merriam-Webster, “Parasite”). Although there are many instances to support insect zombification, provided below is an example below focusing on parasite life cycles that can potentially impact humanity.
Euhaplorchis californiensis is a parasitic worm that “infects three other species” (Dennis) and “alters the behavior of two of them” in its life cycle. The eggs of the parasitic worm “are consumed by horn snails” and, sometimes living in the snail for numerous generations, hinders “the snail’s fertility”. Eventually the parasite will leave “the snail and infect the gills of a killifish. Zombification occurs when the worms then “surround the fish’s brain and cause it to swim near the surface and wiggle around”. This causes the fish to attract a bird and then be eaten, “which is what E. californiensis wanted in the first place”, and then the worm lays its eggs in “the digestive system of a bird”. From here, the bird emits the parasite “where the snails can reach them”, thus bringing the cycle full-circle.
“Although not undead in the strictest sci-fi definition of ‘zombie,’ these captive creatures nonetheless behave as if possessed by a force from beyond. That force, however, is often controlling them from the inside, making the unfortunate hosts do deadly things”. Thus as functioning by “dependence on something else for existence or support”, “parasites have managed to take these particular behaviors and mold them to their own advantage”. So not only in terms of parasitism among insects, but regarding the living dead altogether, “we have to go beyond describing behavior; we have to look at how behaviors are changed."
Ophiocordyceps unilateralis is a species of fungus belonging to the genus Ophiocordyceps that has the special ability to infect certain insects, turning them into zombified drones whose sole purpose is to find an optimal location for the fungus to grow and spread to other insects of nearby colonies. Once Cordyceps successfully finds a host, it alters the insect's behavior so that the insect can wipe out entire populations of ants or arachnids in the course of a few days.
It is common knowledge that The Last of Us, a video game by Naughty Dog, is based on this parasitic fungus. As of right now, Cordyceps cannot transfer from insects to humans, but it may gain this ability from evolving or randomly mutating over a long period of time.
Dennis, Felix. “Invasion of the Zombie Animals.” Mental Floss. Felix Dennis, 2015. Web. 03 Oct. 2015. http://mentalfloss.com/article/21655/invasion-zombie-animals.
Merriam-Webster, Incorporated. “Parasite.” Merriam-Webster. Merriam-Webster, 2015. Web. 03 Oct. 2015. http://www.merriam-webster.com/dictionary/parasite.
“Zombie Creatures: What Happens When Animals Are Possessed by a Parasitic Puppet Master?.” Scientific American Global RSS. Scientific American, A Division of Nature America, Inc., 2015. Web. 03 Oct. 2015. http://www.scientificamerican.com/article/zombie-creatures-parasites/.
Castro, Joseph. "Zombie Fungus Enslaves Only Its Favorite Ant Brains." "LiveScience". Joseph Castro, 2014. Web. 08 Oct. 2015. http://www.livescience.com/47751-zombie-fungus-picky-about-ant-brains.html