If you found the famous HBO series The Last of Us to be a closer-to-reality depiction of how a zombie outbreak might unfold, you aren’t alone. It may not be real enough to give you sleepless nights and ignite apocalypse contingencies, but a fungus controlling the mind of its host like a zombie to spread is very real.
The difference is, in this particular case, these hosts aren’t human.
Entomophthora muscae is a pathogenic fungus, much like the Cordyceps that take over most of the world’s population on the show. In real life though, E. muscae seeks hosts among insects, rather than humans. Its preferred host is generally the housefly (Musca domestica), though the fungus has also been known to infect fruit flies.
Mind-controlling parasites are not new to the animal world, but what makes E. muscae stand out is how effectively the fungus spreads in its vicinity. In any given room or area, the fungus can easily infect 60-80 percent of the flies available.
Entomophthora Muscae Times Its Actions To Perfection
The infection cycle of E. muscae is both efficient and deadly. The fungus begins by releasing spores, or conidia, into the environment, where they latch onto unsuspecting houseflies. Once a fly is infected, the spores germinate and penetrate the host’s cuticle, entering the hemocoel (the primary body cavity of insects) where they proliferate.
For a parasitic fungus, E. muscae does not immediately take over its host. In fact, it lets the fly run the show while feeding on everything that doesn’t affect the fly’s bodily functions, according to a November 2021 study published in IMA Fungus.
The fungus first extracts fats and nutrients with precision—trying not to kill its host too quickly. During this time E. muscae uses the fly’s body as both a food source and a mobile vessel for its spread. Once the fly is well and truly starved, the fungus turns its attention towards the fly’s non-vital organs.
At the same time, it begins to alter the fly’s behavior. The fungus subtly disrupts the fly’s normal physiology, redirecting its energy toward fungal growth while weakening its natural responses. As the fungus proliferates, it triggers “summit disease,” compelling the fly to climb to elevated positions such as plant stems, walls, or window edges.
Death follows swiftly after summit disease sets in. Post-mortem, E. muscae breaks through the fly’s exoskeleton, producing a fresh wave of conidia that erupt from the cadaver. These spores are carried by wind or direct contact to new hosts, beginning the cycle anew.
The Fungus Seduces Male Flies To Spread Faster
Beyond its ability to manipulate living flies, E. muscae wields another sinister tool in its arsenal: turning the corpses of its victims into irresistible traps for healthy male flies.
To reel in any males buzzing about, the fungus releases volatile chemicals from the bodies of infected female flies, according to a July 2022 study published in The ISME Journal. Drawn by these compounds, the males attempt to mate with the cadavers, unknowingly exposing themselves to the fungus’s infectious spores.
The exact nature of this deadly attraction remains unclear. One hypothesis suggests that the volatiles may mimic signals associated with food or potential mates, enticing the males to investigate further. However, once in close proximity, it appears that less-volatile compounds emitted from the cadaver trigger a behavioral shift in the flies, eliciting attempts to mate.
Researchers may yet be a while away from fully understanding this behavior, but the recent sequencing of the E. muscae genome has nevertheless unearthed a treasure trove of information to help them paint a better picture of the fungus’s incredible abilities.
E. Muscae Was Meant For The Mind-Control Life
At the molecular level, E. muscae employs an arsenal of tools found in its genome to dominate its host. The fungus first produces enzymes that break down host tissues and potentially interfere with immune defenses, clearing the path for systemic invasion.
As the infection advances, the fly’s blood-brain barrier becomes permeable, allowing the fungus to manipulate neural circuits with even greater precision. Researchers have also discovered the presence of a fungal gene much like one called ecdysteroid UDP-glucosyltransferase, or “egt”—a viral gene that compels its infected victims to climb to higher surfaces.
What makes E. muscae’s biology all the more remarkable is that the fungus does not operate alone. Behind the scenes, the fungus is also infected by a virus (Berkeley entomophthovirus) even as it continues to feed on its victims. While it is yet unclear how much this virus influences the actions of the fungus, other members from this family of viruses have been known to manipulate insect behavior, according to an August 2024 study published in G3: Genes, Genomes, Genetics.
The sequencing of E. muscae’s genome has marked a significant shift in our understanding of the nature of this unique fungal infection and opens the doors to a number of potential human applications. Researchers are particularly excited by the possibility of harnessing this phenomenon as a form of biocontrol, while it could even find potential applications in the world of mental health treatments.
Ultimately, E. muscae’s blend of biochemical, neurological and behavioral manipulation underscores the remarkable—and terrifying—adaptations of this fungal pathogen. Its devastating impact also highlights the evolutionary sophistication and efficiency that can be found in the most unexpected places in the natural world.
Entomophthora muscae’s life cycle reflects the morbid underbelly of survival and proliferation in the natural world. Some might find this creepy, while others might appreciate the ingenuity at play. Take this 2-minute quiz and find your place on the Animal Attitude Scale.
