An international team of researchers, including experts from the University of Copenhagen, has successfully mapped the genetic blueprint of a unique fungus that turns common flies into "zombies." This fungus, Entomophthora muscae, which can infect 60-80% of flies in your home, could pave the way for new developments in both insect repellents and psychotropic drugs.
The Fungus That Turns Flies Into Zombies
The Entomophthora muscae fungus has fascinated researchers for years, particularly Henrik De Fine Licht, an associate professor at the University of Copenhagen's Department of Plant and Environmental Sciences. This fungus doesn't just kill flies; it takes control of their behaviour, effectively turning them into mindless zombies before eventually killing them. The team's recent achievement in sequencing the fungus's genome is a major step toward understanding how this complex manipulation occurs.
"The genome acts as a comprehensive catalogue of the fungus's genes, offering insights into its capabilities," says De Fine Licht. "By identifying which genes are active in a fly's brain during its zombification, we hope to uncover the mechanisms behind this extraordinary process."
Fly infected by fungus (credit: Filippo Castellucci)
The Grim Life Cycle of the Fly Fungus
Entomophthora muscae is highly specialized, targeting specific fly species. The researchers focused on a subspecies that infects fruit flies, mapping its extensive genome—about 25 times larger than most fungi. The infection process is as eerie as it is efficient: the fungus invades the fly, slowly consuming it from the inside while it’s still alive. Once the fly is nearly depleted of nutrients, the fungus takes over its brain, compelling it to climb to a high spot and adhere to a surface like a window or plant.
"At this stage, the fly is almost entirely fungal mass. The fungus then releases spores from the fly's body, accompanied by chemicals that attract healthy flies," explains De Fine Licht. "These flies, driven by the lure, attempt to mate with the dead fly, thereby spreading the infection."
Decoding the Fungus's Genetic Secrets
While the fly fungus's life cycle is well-documented, the underlying mechanisms have remained largely mysterious—until now. The genome sequencing has revealed unique genes that appear to be crucial for the fungus's precise control over the fly's behaviour.
"The behavioural manipulation always begins at dusk, likely because higher humidity at night makes it an optimal time for spore dispersal," says Carolyn Elya of Harvard University, the study's last author. "The fungus has genes that produce light-sensitive proteins, suggesting it uses light cues to time its actions, a crucial discovery in understanding the zombification process."
The research also uncovered that the fungus possesses numerous copies of enzymes adept at breaking down the tough chitin shells of insects, confirming its specialized evolutionary adaptation to thrive within its insect hosts.
Potential Applications: From Mental Health to Pest Control
Though this research is still in its fundamental stages, the implications are vast. Understanding how Entomophthora muscae controls insect behaviour could provide valuable insights into human brain function and behaviour, potentially inspiring new treatments for mental illnesses.
"In studying this fungus, we have a model where behaviour is clearly and predictably manipulated by an external organism. By decoding this process, we might unlock new avenues for drug development aimed at treating mental health disorders," De Fine Licht suggests.
Additionally, the fungus's highly targeted nature makes it a promising candidate for biological pest control. Current pesticides often harm beneficial insects like honeybees, but a fungicide based on Entomophthora muscae could offer a species-specific solution, attacking only the intended fly species.
"Developing an insecticide derived from this fungus would be highly attractive, as it could effectively target pests without harming other insects," De Fine Licht concludes. The full research findings have been published in the journal eLife, marking a significant step forward in our understanding of this remarkable fungus and its potential applications.
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