Zombie-ant fungus feast: New research is uncovering how zombie-ant fungus might control its hosts. But this parasite also has its own fungal threats.
Image: Wikimedia Commons/David Hughes/Maj-Britt Pontoppidan/PLoS ONE
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An unsuspecting worker ant in Brazil's rainforest leaves its nest one morning. But instead of following the well-worn treetop paths of its nest mates, this ant stumbles along clumsily, walking in aimless circles, convulsing from time to time.
At high noon, as if programmed, the ant plunges its mandibles into the juicy main vein of a leaf and soon dies. Within days the stem of a fungus sprouts from the dead ant's head. After growing a stalk, the fungus casts spores to the ground below, where they can be picked up by other passing ants.
This strange cycle of undead life and death has been well documented and has earned the culprit the moniker: "zombie-ant" fungus—even in the scientific literature. But scientists are just learning the intricacies of this interplay between the Ophiocordyceps parasitic fungus and the Camponotini carpenter ants that it infects. Fossil evidence implies that this zombifying infection might have been happening for at least 48 million years. Recent research also suggests that different species of the fungus might specialize to infect different groups of ants across the globe. And close examination of the infected ant corpses has revealed an even newer level of spooky savagery—other fungi often parasitize the zombie-ant fungus parasite itself.
"We have advanced a great deal in understanding how the fungus controls ant behavior," David Hughes, an assistant professor of entomology and biology at The Pennsylvania State University, says. Every few months scientists are discovering yet another peculiar trait that, added together, make this parasite one of the most insidious infections—or perhaps that honor goes to the parasite that ultimately kills the killer parasite.
Deadly infection
This clever Ophiocordyceps fungus depends on ants to reproduce and spread, but it has found an abundant host animal. As Hughes notes, ants have been incredibly successful, currently comprising an estimated half of all insect biomass worldwide.
One of the first clues that a tropical carpenter ant has become infected with Ophiocordyceps is that it will leave the dry tree canopy and descend to the humid forest floor, staggering over debris and plants. "Infected ants behave as zombies," Hughes and his colleagues wrote in a 2011 BMC Ecology paper describing some of the latest findings. The ant will walk randomly, displaying "convulsions that make them fall down and thus preclude them from returning to the canopy," they noted, comparing the stumbling gait with a "drunkard's walk."
The clumsiness cannot, however, be blamed on the ant. "While the manipulated individual may look like an ant, it represents a fungal genome expressing fungal behavior through the body of an ant," the researchers noted in the paper. Hence the zombie designation.
Evans suggests that a nerve toxin spurred on by the fungus is at least partly to blame, "judging from the uncoordinated movements and hyperactivity of the ants infected," he says. Ants that have been dissected at this stage of infection reveal heads already full of fungal cells.
Eventually, an affected ant will stop on the underside of one leaf, roughly 25 centimeters from the forest floor, and clamp down on the leaf's main vein. (This position appears to be optimal for the fungus's later stage in which it ejects spores onto the soil directly below.) Biting leaves is not normal ant behavior. The zombies' bites are synchronized near noon (possibly cued by clock genes in the fungus) and usually occur in a north-northwestern orientation.
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19 Comments
Add CommentAnd so it has begun...
Reply | Report Abuse | Link to thisWow. These are some of the coolest parasites in the world. Just...wow.
Reply | Report Abuse | Link to thisRe (p. 2): "The zombie fungus, however, cannot live without the winning ants' continued success. It appears to be an obligate parasite, requiring a specific, local species of ant for it to inhabit, grow and propagate its spores."
Reply | Report Abuse | Link to thisParisitism, especially that which is species specific, is fascinating. What is the evolutionary explanation for how these biological organisms were abel to "team up?"
I wonder if it would be possible for human brains to become infected with any sort of zombie fungus. I know that rabies virus can sort of turns humans into zombies.
Reply | Report Abuse | Link to this"Team up"? No. The fungus had a golden opportunity, took it, and became so reliant upon said opportunity (parasitizing ants) that it lost the ability to survive without it.
Reply | Report Abuse | Link to thisEverything's a continuum in evolutionary biology. There are cases of facultative parasitism and mutualism, parasites that are more specialized than *Ophiocordyceps*, and parasites that are much more generalized. If you continue to advocate creationism on SciAm, I will report you. Furthermore, if you persist, I will start spamming creationist websites and hangouts in the same manner in which you spam SciAm. Just imagine it--me, in that laughable "creation museum", burning bibles and lecturing about how they are literally full of lies and communism. Of course, I probably would wait on a step like that until someone like Toad Akron the Magic Vagina Guy actually got elected, but the image of me doing something so drastic (but protected by the First Amendment) ought to keep you away. Go mess with Richard Dawkins.
Evolution is the successful outcome of random events. The passionate curiosity of our minds can lead us to create answers to alleviate the angst of uncertainty.
Reply | Report Abuse | Link to this"""What is the source of the opportunity?"""
Reply | Report Abuse | Link to thisReally? Are you suffering from mental retardation? Read my comment; I explained it to you.
"""Re: "If you continue to advocate creationism on SciAm, I will report you."
This has really gotten old. You've already reported me by virtue of the fact that the author of this web page has the authority to block my comments as has been done on four other web pages."""
Then why haven't you taken the hint? If you've been banned four times, you're clearly doing something wrong.
"""Re" ...protected by the First Amendment..."
Are you the only citizen of this nation who is protected by the First Amendment?"""
Nope. Anyone in the country has the right to say the stupidest things that he or she can imagine. You seem to exercise this right at every opportunity, BTW.
Technically, you are allowed to be a creationist on SciAm, but that means that I can say that your bible is a pack of lies as often as I like whenever and wherever I like, including on creationist sites. Don't try to use my arguments against me; I am known for my ability to tear apart the arguments of people who do so.
Furthermore, you are allowed to burn any books or flags that you like, as long as said books or flags belong to you. You are not, however, allowed to attempt to pass off your ridiculous views as science. The Supreme Court has made several decisions to that effect.
Bird/tree/dinosaur/etc. geek,
Reply | Report Abuse | Link to thisRe: "Read my comment..."
Better yet, here it is reproduced: "Team up"? No. The fungus had a golden opportunity, took it, and became so reliant upon said opportunity (parasitizing ants) that it lost the ability to survive without it.
That is not an explanation, it's an assertion. An explanation should require evidence.
Re: "...I can say that your bible is a pack of lies..."
At the risk of having you tear me apart:
THE BOOK OF PSALMS
49:1. A psalm for Asaph. The God of gods, the Lord hath
spoken: and he hath called the earth. From the rising of
the sun, to the going down thereof:
[Catholic Bible. (c) 2000. Douay Rheims translation. Murray, KY: A production of Catholic Software]
http://www.youtube.com/watch?v=Cw_JfsU0OWY
http://www.youtube.com/watch?v=8tyNaJxZ76A
First comment: I'm not here to do your homework for you. If you were willing to make the effort to understand evolution, you would.
Reply | Report Abuse | Link to thisSecond: Sorry, but the bible is a pack of lies. Religion is hookum. Your quote is taken from the bible, and therefore is not acceptable evidence.
Has anyone told the Umbrella Corp. about these fungi?
Reply | Report Abuse | Link to this8^)
Bird/tree/dinosaur/etc. geek,
Reply | Report Abuse | Link to thisYou were not asked to do my homework, only your own.
As regards the Bible, your claim will only be credible to the extent that you provide evidence for it.
There is never going to be direct evidence of the first parasitic infection, these things happen far to long ago and to such delicate structures it's not going to have survived. As to how, here's a situation, ant/ant relative bug gets stepped on, fungus spore lands on spilled guts, eats thrives releases spores near ant colony. More ants from colony get stepped on spilling more guts, feeding more fungus, ad infinitum. With each subsequent spore getting every so slightly more dependent on the ant guts.
Reply | Report Abuse | Link to thisZexks,
Reply | Report Abuse | Link to thisRe: "There is never going to be direct evidence..."
The late Prof. Stephen Jay Gould seem to have made a similar admission over 3 decades ago:
"As a paleontologist and evolutionary biologist, my trade is the reconstruction of history....Scientists who study history, particularly an ancient and unobservable history not recorded in human or geological chronicles, must use the inferential rather than experimental methods."
[1978. Senseless Signs of History. NATURAL HISTORY, October, p. 22]
Inference, bereft of evidence, then, would seem to be the stock-in-trade of evolutionists.
Bird/tree/dinosaur/etc. geek,
Reply | Report Abuse | Link to thisRe: "...[G]et off of this thread. We all hate you, so please go away."
Ok.
THE HOLY GOSPEL OF JESUS CHRIST ACCORDING TO SAINT MATTHEW
5:44. But I say to you, Love your enemies: do good to them that hate you: and pray for them that persecute and calumniate you...
[Catholic Bible. (c) 2000. Douay Rheims translation. Murray, KY: A production of Catholic Software]
Now that is a good question. If the parasitic fungi actually represent potentially hundreds of different species respective to their ant hosts' species, then that would seem to indicate a high degree of ability to change. The Walking Dead a little closer to reality.. :-)
Reply | Report Abuse | Link to this[quote]
Reply | Report Abuse | Link to thisThe late Prof. Stephen Jay Gould seem to have made a similar admission over 3 decades ago:
"As a paleontologist and evolutionary biologist, my trade is the reconstruction of history....Scientists who study history, particularly an ancient and unobservable history not recorded in human or geological chronicles, must use the inferential rather than experimental methods."
[1978. Senseless Signs of History. NATURAL HISTORY, October, p. 22]
Inference, bereft of evidence, then, would seem to be the stock-in-trade of evolutionists.
[/quote]
On the chance that this might be a useful discussion to some reders, I'll respond.
Your conclusion is wrong because it make the overt assumption that inferential logic is "bereft of evidence". Inference requires evidence. Consider any detective novel. The difference is how direct is the evidence. If this was a discussion about a murder mystery, it is clear we cannot use experimental methods to recreate the murder (that would involve reversing time or at least resurrecting the victim). We have to use inferential methods in this case (e.g. bloody fingerprints or the weapon or other clues).
Using either method, you have to build a case for the conclusion. I'm a Bible believer, but I do not see it as a science textbook. The case for evolution seems very strong. At leaast a few orders of magnitude stronger than the case for literal interpretation of all of the Bible. Since you quoted the Douay Rheims (Catholic) translation, I'll mention that even the Catholic Church does not take a literal approach and accepts evolution. I actually find it interesting that evolutionary evidence suggests all modern humans decended from a single female (based on mitochondrial DNA). Difference is the literal interpretation puts Eve a few thousand years ago while science puts it back a million or so years ago.
So your quote about inference is right, but your conclusion derived from it is very wrong.
Toxoplasmosis (caused by an accidental protist infection) can alter behavior patterns, so it's not that much of a leap.
Reply | Report Abuse | Link to thisCould this fungus be infecting Democrats?
Reply | Report Abuse | Link to thisHmmm, probably not. In this case, The fungus kills the host. Liberalism, the disease affecting democrats, just leaves them damaged and with a desire to kill the rest of us (economically and sometimes literally). After we die, of course, then there's nothing left to feed on, so then they die. They are more of an excellent example of kleptoparasitism :-)
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