OK, so ants are not particularly well regarded creatures. They’re ugly, they ruin picnics, and they get in your pants and cause you to become worried or excitable (in accordance with the famous idiom). With this in mind, ant-haters will perhaps be pleased to hear that the humble ant has a very powerful and cunning nemesis, capable of exploiting its vulnerable mind. Even in scientific literature, this ingenious parasite has been dubbed the zombie ant fungus.
Zombie Ant Fungus
The nemesis in question is a fungus of the Ophiocordycipitaceae family. The fungus was first discovered by a British mycologist, called Tom Petch, way back in 1931. So far, at least 140 species of the genus are known to exist, each capable of growing aboard an unsuspecting insect host.
Looking specifically at the ant population, however, Ophiocordyceps unilateralis is the mind-leeching parasite responsible for creating extensive hoards of the zombie creatures. Once the fungus has infiltrated the ant’s brain, the insect becomes powerless to resist the calculated directives of its subversive ruler.
The dazed and confused ant then stumbles around aimlessly, unable to gain its bearings, ultimately, breaking formation from its meticulously organized colony. Once the fungus has gained total dominance, and the ant’s mind is truly broken, the hollow shell of a creature is compelled to find a specific location within its habitat.
The Spread of Infection
The zombified organism begins its ascent of leafy foliage. According to studies, infected ants display “death-grip behavior,” using their powerful mandibles to pierce organic structures within vegetation to anchor them to the spot; the ant’s mandibles then atrophy, causing lock-jaw. Once this has been achieved, the fungus performs its final coup de grâce, ending the ant’s miserable existence, once and for all.
Ants generally tend to form vast colonies, arranged across different subsets of territories. These biological conclaves are sometimes referred to as “superorganisms” due to the highly advanced interplay between individual units. This is one of the ant species’ greatest strengths, but, when it comes to its fungal foe, it is also one of its greatest weaknesses.
In spectacularly horrifying fashion, as the ant perishes, the fungus breaches the poor creature’s head and begins to grow at a rapid pace. By transporting the infected ant to an elevated position, the fungus has managed to successfully acquire a prime position for infecting the remaining ant population. After the fungus has fully grown, jutting some distance from its victim’s lifeless corpse, a burst of spores is showered down over the ant’s former colleagues.
The fungal spores then attach to the exoskeletons of the flurrying ant population, repeating the same gruesome cycle.
Interestingly, the ants have managed to develop a rudimentary, but effective, defense mechanism to combat the deadly fungal parasite. Once a member of the colony begins displaying the characteristic signs of infection, a fellow worker ant will cart the dangerous subject off to a remote location and dispose of it; an act lacking in chivalry, but one born out of necessity to save the remaining colony.
A Fungal Parasite’s Parasite
In quite an astounding twist, the parasitic fungus also has its own adversary – another fungus. This is, quite conceivably, another means of keeping the whole cycle in check. If Ophiocordyceps unilateralis was left entirely unregulated, the ant population would quickly become overwhelmed, resulting in both the ant and fungal populations dying out.
This hyperparasite is found to grow over the ends of the stalks of the zombie ant fungus, essentially serving to sterilize it. Sandra Andersen, a researcher with the University of Copenhagen, indicates the intricate battle that plays out between the different organisms:
“They’re not really growing on anything else… Once you’re very successful, something else will take advantage of it… It’s really a little ecosystem in its own [right].”
According to David Hughes, who works at Penn State as a behavioral ecologist, the zombie ant parasite’s supreme virulence leaves it vulnerable to attack from other organisms. According to the research data collected by Hughes and his colleagues, whilst operating in Southern Thailand, as little as 6.5 percent of the zombie ant fungi’s spores will survive to fruition, due to predation from this opposing fungal challenger; a parasite of a parasite, if you will.
How this amazing, mind-controlling feat is achieved, for the time being, remains a mystery. Hughes and his team are currently conducting laboratory investigations to determine what mechanisms or chemicals are being deployed by the zombie ant fungus to induce obedience in its subdued victims.
In terms of the future, Hughes imagines these results could provide useful information applicable for pest control in agricultural circles:
“Lots of the pure discoveries we make have great import for food security and the challenges farmers in tropical countries face from insects and fungi that infect their crops.”
Another miraculous feat of nature rears its disturbing, mind-controlling head. Do you thank the horrifying fungus for its impact in lessening the ant population, or do you think the creation of zombie ants is a barbaric aberration of the natural world that should never have been?
By: James Fenner