What Is Zombie Fungus
Ophiocordyceps unilateralis sensu lato - a complex of species sometimes called the "zombie ant fungus" - surrounds and invades muscle fibers throughout the ant's body, and fungal cells form a three-dimensional network that allows them to collectively control the host's behavior. - said the researchers.
The fungi attach to plants and release antibacterial chemicals to protect themselves, and grow fruiting bodies from the ants' heads to release their spores, producing the next generation of fungi.
It has been known to infect and destroy entire carpenter ant colonies, leaving behind a dense, well-ventilated graveyard of ant carcasses. A parasitic fungus, for short), infects the brains of wood ants, turning them into zombies that live and die in order to help the fungus thrive and reproduce.
Under the influence of the fungus, carpenter zombie ants leave the nest at a strange but determined time, moving in chaotic and convulsive movements, climbing exactly 25cm along the north side of the plant, where they bite into the veins of the leaves.
The fungus eats the internal organs of ants, using their shells as a protective coating. The main stem of the fungus (stroma) grows out of the nape of the ant and grows.
When a fungus first enters its host, it exists as individual cells that float in the ants' bloodstream, producing new copies of themselves.
The fungus grows throughout the ant's body cavity, using the internal organs as food, while the ant's durable exoskeleton acts as a kind of capsule, protecting the fungus from drying out, ingesting, or further infection.
Researchers believe that a fungus found in rainforests infects forage ants through spores that attach to and penetrate the exoskeleton, gradually changing their behavior. A few days after the ant dies, the fungus sends a fruiting body across the base of the ant's head, transforming its withered corpse into a stepping stone from which it can dump its spores and infect new ants.
As with the zombie legends, there is an incubation period where the infested ants appear perfectly normal and go about their business unnoticed by the rest of the colony.
If this is a deliberate act of the ant, it can save the rest of the colony from contracting an infection sometimes called "adaptive suicide."
It is unclear if this behavior is a zombie condition caused by a fungus or an altruistic act of self-sacrifice on the part of the ant. In other words, the parasite takes over the ant's mind, forcing it to feed on other insects.
First, it affects the behavior of ants through convulsions, due to which they fall from their nest under a canopy high on the forest floor. First, it releases spores, which are then carried through the air until they reach the ant (Lu, 2019).
A stem then grows that releases spores from the back of the victim's head to infect more ants on the ground below. Once the mushroom kills its unfortunate drone, a stem grows that releases spores from the ants' heads to infect even more ants.
When the fungus releases spores, it creates what the authors describe as an “infectious extermination camp,” about one square meter below the ant's body, which can infect C. leonardi ants or similar species that are unfortunate enough to walk in it.
Other fungal parasites also control their insect hosts as if they were zombies. This means that after the death of the ant, the fungus can continue to grow and then leave the ant's body, sometimes in the form of fungal stems.
Thus, the fungus benefits from this because the infectious spores end up underground where they can infect other drill ants.
New research shows that the fungal parasite does all of this without infecting the ants' brains. Meanwhile, "the cuticle of ants ... is transformed into a protective shell by strengthening the weaker parts," and the parts of the fungus in the ant's body appear to differ in individual functions, the researchers write.
The team found that ants infected with the fungus climb high places and bite into vegetation, permanently entrenched.
After a leaf bite, the infected ants always died, since this is necessary for the subsequent growth of the fungus. It has since been found that the fungus disrupts the ant's normal behavior by chemically interfering with the brain, causing the infected ant to behave in a way that improves the fungus's ability to spread its spores and then reproduce.
The fungus that invades the ant's body is known as the genus Cordyceps and includes many species of fungi. This connection between ant and fungus is obviously ancient, but it is also very common: to date, about 1000 species of fungal insect parasites have been discovered.
In addition, it has been suggested that their morphological variations may also be the result of the fungus species maximally infecting a particular host ant species (host-specific infections).
In 2011, it was suggested that the zombie ant fungus could in fact be described as a host-specific species complex, meaning that one O. unilateralis species can successfully infect and manipulate only one host ant species.
There has been a lot of controversy over whether zombie ants (and other mushrooms) belong to one or the other, since Ophiocordyceps was introduced very recently. We found that the zombie ants were likely descended from an ancestor that infected the larvae of beetles living in decaying soil or wood, similar to the Ophiocordyceps species that infect existing beetles.
Surprisingly, the leap has resulted in widespread species radiation observed after the development of behavioral manipulation. The authors also studied the effect of the fungus on the ant of the genus Polyrhachis and found that not all of its manifestations were reported.
The team injected the fungal material (in liquid medium) into two species of ants, Camponotus pennsylvanicus and Formica dolosa, who, despite living in the same area as other ants, were not known to carry the fungus.
The team placed several ant colonies in the lab, infected some with the fungus, and watched as the ants got sick and violently blocked anything they might find. The control group was infected with a single fungus, Beauveria bassiana, which also killed the ants without causing death.
All of these individuals exhibited seizures that were unevenly distributed throughout the body (vertical bars in the periodogram in Figure 1), which often resulted in ants falling from vegetation to the ground (indicated by asterisks in the periodogram).
To see how important this precision is to the fungus, the researchers identified dozens of infested ants in a small patch of forest. It was confirmed that all 21 zombie ants we observed were infected by dissecting the head to detect fungal cells or by observing the emergence of O. unilateralis s.l.