Zombie fly fungus attracts healthy male flies to mate with dead females

Zombie fly fungus attracts healthy male flies to mate with dead females

Zombie fly fungus attracts healthy male flies to mate with dead females

A male fly trying to mate with a female corpse held in place with some petroleum jelly. The fungus has grown out of the rear segment of the body and is visible as large white spots from which spores are ejected. 1 credit

Entomophthora muscae is a common pathogenic fungus that survives by infecting common house flies with deadly spores. Now, research shows that the fungus has a unique tactic to ensure its survival. The fungus “bewitches” male house flies and leads them to necrophilia with the fungus-infected corpses of dead females.

After infecting a female fly with its spores, the fungus spreads until its host is slowly consumed alive from within. After about six days, the fungus resumes the behavior of the female fly and the strength at the highest point, whether on vegetation or on a wall, where the fly then dies. When the fungus has killed the female zombie, it begins to release chemical signals called sesquiterpenes.

“The chemical signals act like pheromones that bewitch the male flies and cause them to crave an incredible urge to mate with the carcasses of lifeless females,” says Henrik H. De Fine Licht, associate professor in the Department of Human Sciences. Environment and Plants from the University of Copenhagen and one of the authors of the study.

When the male flies copulate with dead females, the fungal spores are dumped on the males, who then suffer the same horrible fate. In this way, Entomophthora muscae spreads its spores to new victims and ensures its survival.

This is the conclusion of a new study conducted by researchers from the University of Copenhagen and the Swedish University of Agricultural Sciences in Alnarp.

“Our observations suggest that this is a very deliberate strategy for the fungus. It is a true master of manipulation – and it is incredibly fascinating,” says Henrik H. De Fine Licht.

Fly corpses become more appealing over time

Tracking fly behavior also allowed the researchers to demonstrate that dead female flies become more attractive over time.

Specifically, 73% of the male flies in the study mated with carcasses of female flies that died of fungal infection between 25 and 30 hours earlier. Only 15% of the males mated with the corpses of females that had been dead for 3 to 8 hours.

“We find that the longer a female fly has been dead, the more attractive it becomes to males. This is because the number of fungal spores increases over time, which enhances the attractive scents,” says Henrik H. De Fine Licht.

Besides insight into the fascinating mechanisms of nature, the study provides new insights that could lead to effective fly killers in the future. Henrik H. De Fine Licht adds:

“Flies are quite unsanitary and can make humans and animals sick by spreading coli bacteria and all the diseases they carry. Thus, there is an incentive to limit house fly populations, in areas where food is produced for example. This is where Entomophthora muscae can come in handy. It might be possible for us to use these same fungal scents as a biological pest control that attracts healthy males to a fly trap at the instead of a corpse”, he concludes.

The research has been published in The ISME magazine.

Research explained

  • The researchers used a range of methods. These included chemical analysis of scents emitted by the fungus and amplified in dead female flies, as well as studying the genetics of the fungus via RNA sequencing.
  • They also studied the sexual habits of male flies through behavioral experiments exposing them to dead female flies that were in various stages of fungal infection, as well as dead females from other causes. Here, the researchers’ observations demonstrated that the male flies preferred to mate with fungal-infected females that had been dead for some time.

Learn About Zombie Fly Fungus

  • Entomophthora muscae is a fungus that survives by taking over and infecting its host, namely flies.
  • The fungus secretes special enzymes that break down a fly’s body in about seven days. The fungus can eject its infected spores up to 10 meters per second, which is among the fastest movements in nature.

A fungus that uses chemicals to trick male flies into mating with infected dead females

More information:
Andreas Naundrup et al, the pathogenic fungus uses volatile substances to induce male flies to mate with corpses of infected females, The ISME magazine (2022). DOI: 10.1038/s41396-022-01284-x

Provided by the University of Copenhagen

Quote: Zombie fly fungus attracts healthy male flies to mate with dead females (July 15, 2022) Retrieved July 16, 2022 from https://phys.org/news/2022-07-zombie -fungus-lures-healthy-male.html

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