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Nature is fascinating. It can be the source of amazing beauty, but it can also be incredibly terrifying. The cordyceps fungus falls in the category of terrifying—it literally makes zombies. But don’t run and hide just yet – there is a bit of good news. The cordyceps fungus (in all its variations) only attacks insects.
We weren’t kidding about the zombie part. The cordyceps fungus invades its insect host and starts by consuming non-vital organs, and that’s just the warm-up. Next, it spreads to muscles and the brain, where it gains control of the insect’s body. Zombie-fication ensues when a cocktail of mind controlling chemicals is released that hijacks the nervous system, forcing it to do the bidding of the fungus.
Under the fungus’ control, a zombie insect will climb up to an altitude optimum for spore growth. This shell of a body clamps onto a leaf while being consumed from the inside out, turning it into a breeding ground for more fungus spores. This is typically a stalk of some sort that grows out of the victim’s head after bursting its way through the insect’s exoskeleton from the extreme pressure it creates. These new spores rain down upon the insect’s former compatriots, creating what can be described as a “killing field” of spores.
Yeah. This kind of makes John Carpenter stories seem like children’s fairy tales by comparison. But if you get past the absolute horror of it, it is a fascinating example of the delicate balance of nature.
You see, there are thousands of different varieties of the cordyceps fungus. Each one specializes in a single insect species that it can control with its zombie-making abilities. These different fungi can attack ants, wasps, flies, moths and other species. Remarkably, it turns out that these attacks can positively impact the diversity of individual ecosystems. These fungi help to keep populations in check and prevent certain species from dominating over others. The targeted species themselves develop defenses against the fungi, preventing them from being wiped out in the delicate dance of evolution.
While we are still increasing our understanding of the complicated relationship between the cordyceps fungi and insects, it appears that this parasitic bond might have been an ancient development. Bite markings on leaf fossils that match the current behaviour of infected ants could indicate this zombification has been an ongoing evolutionary process spanning the past 48 million years.
The life of a zombie fungus isn’t without stress, though. The cordyceps fungi are themselves susceptible to attack from other fungi that limit their ability to grow viable spores, inhibiting the spread to other insects. That’s the beauty of nature; it is a system that has evolved checks and balances for almost everything.
Although cordyceps fungi are unable to infect humans, don’t get too comfortable. Scientists estimate that only about 7% of the species in the fungi kingdom have been identified. That’s a whole 93% left that could potentially start the zombie apocalypse!