Zombie Insect Apocalypse

Zombie fungi is considered as the most disturbing of organisms discovered and it is only recently scientists are beginning to gain a better understanding.

A close up of a dead ant with the zombifying fungus growing from its head.All images courtesy Dr. David Hughes

The grey stalk is a separate fungi organism (which is infact made of 4 different species) that grows on the insects head. The fungus species can infect an ant, take over its brain, and then kill the insect once it moves to a location ideal for the fungi to grow and spread its spores.

In the early stages fungus kills the ant and there is a small pioneer growth as fungi inside the ant erupt out through a cuticle. According to the online journal PLoS ONE, these newly found fungus species also have the power to control an ant’s mind and manipulate their behaviour. This act of ‘brainwashing’ parasitism leads ants away from their colonies to end up on a ideal reproductive site for the fungus. These mind controlling fungi are most commonly present in Brazil’s Amazon rainforest.

Fungi growing from a dead ant

The fungus rapidly consumes the nutrients inside a zombie ant and begins to colonize the outside of the ant’s body, as shown.

It fills the ants head with fungal cells and chemicals that changes its muscles so the ant can grab a leaf in a death grip just when and where the fungus wants it. The bizarre sequence that leads up to the ant’s death is completely absurd compared to the ants normal behaviour and appears to be a method for the fungus to get itself to the perfect area to spread its spores, according to researchers.

Hughes and colleagues observed a total of 42 infected ants, some of which they dissected. While holding its death grip, the ant’s head was filled with fungal cells and the muscles that operated the ant’s mandible, or jaw, was atrophied, they found.

“In the context of biting, it allows the mandibles, we feel, to work in one direction and one direction only,” Hughes told LiveScience. “Normally, they open and close, but in this case they can only close. This keeps the dying ant from losing its grip. The fungus also appears to suck all of the calcium out of the muscles, causing a condition similar to rigor mortis” he said. Rigor mortis is a common sign of death where the limbs of the corpse become stiff and difficult to move or manipulate.

Ants aren’t the only zombie-fungi hosts—other insects also fall prey to fungus. Here a wasp is infected by a fungus specie that hasn’t yet been named. This Fungi produces a tightly evolved arms race between hosts and parasite. That suggests the ‘zombifying’ fungi are often specialist to infecting a certain specie. Thus there is a potential risk of the fungi specie becoming extinct or dying out if the population numbers of the host specie reduces significantly.

Some have suggested extreme possible implications concerning these ‘zombifying’ fungi by saying they may develop and evolve to infect mammals (including humans). However the possibility of these fungi evolving to infect humans is extremely low, especially because human population density is sparse in areas where these fungi are most commonly found.

Here is a short clip broadcasted by the BBC from Planet Earth narrated by David Attenborough.