There is a "love potion" that makes it uncontrollable to have sex with a corpse and then die.

There may be not a few creatures that can manipulate the behavior of insects, but it may be rare that they can take advantage of their sexual desire to lure them to a dead end.

Spring is coming, everything is reviving, and it is time for animals to breed.

For most animals, sexual reproduction is the main way to reproduce. Strong sexual impulses drive the flesh to give birth to new offspring during mating and contribute to the continuation of the species.

But at the same time, this mission engraved in genes can also be easily used by other creatures. For example, some orchids imitate the shape and smell of some female bees, sending out chemical signals to prepare for mating, luring drones to find a mate and stained with pollen. When the insect is deceived again, it can spread the pollen.

It doesn't matter if it's just this. Insects don't seem to lose much even if they are repeatedly deceived by plants. By contrast, there is a fungus that makes a "love potion" that is more dangerous, in which male houseflies mate with dead females and lose their lives.

Of course, this is not martyrdom, but murder.

How sexual desire is used

The killer's name is Entomophthora muscae, a fungus from the genus Entomophthora, which means "insect destroyer" in Greek.

Muscidae can be parasitized in many species of flies, but the most common human species is probably the Musca domestica. After invading the housefly's body, the fly mold absorbs its hemolymph, the transparent blood-like fluid in the insect, and eats the housefly's fat cells, like a forced liposuction. In this frenzied plunder, the fungal colony continues to grow, and the host housefly will eventually lose its life.

In addition to hollowing out the housefly's body, the fungus will also take over the housefly's brain, making it a puppet and obeying its own command. Houseflies, which are controlled by flies and molds, can't help climbing to a nearby high place, then emit some kind of secretion, stick themselves to that high surface, and never leave until death.

If the infected male fly, the story may end here: it as a parasite of a "nursery", after the last leg of the journey, the body may stay on the window, or on the branches and leaves of a plant. But if the victim is a female fly, after it is killed by the fungus, the body has to cooperate with the fungus to complete the next task.

Previously, scientists have found that when female flies die of infection, males come to mate with these corpses. Researchers at the time thought that such intimate contact could help the fungus spread, but they were not sure whether the fungus had induced the male to have sex in some way to capture the male's body and kill it.

Recently, a research team led by scientists at the University of Copenhagen found evidence that flies and molds lure males to rape corpses.

First, the team infected some female houseflies with fly mold and, shortly after each female died (3-8 hours), put its body in the same space as a healthy male and photographed the bug for 40 minutes. In the control group, uninfected female flies were frozen and shared with a healthy male fly. A total of 15 males participated in the test. It was found that males rode more females killed by fungal infections than frozen females, but the gap was not significant at this time.

However, when the female fly was killed by the fungus for more than one day (26-28 hours), the sexual attraction of the corpse to the male fly greatly increased. In contrast, more than a day after death, the sexual attraction of the frozen female flies in the control group was close to that of males. On average, the bodies of female flies who died of fungal infection were rode by males more than 5 times in 40 minutes, which was about 5 times as frequent as that of the control group (frozen dead female flies).

In other words, female flies infected with fungi were significantly more likely to arouse the sexual desire of male flies than uninfected female bodies a day after death. By the way, when scientists replace female bodies with male bodies, it is difficult to attract healthy males with or without fungal infection.

On this basis, the team did a second experiment. This time, the researchers put healthy males and two female carcasses in the same space, a female that died a day after infection and an uninfected female, allowing the male to choose between them. The control group was a male fly that lived with two female carcasses that were not infected with fungi.

The experimental results are very interesting. In the case of the coexistence of infected and uninfected female flies, the number of male flies riding the dead was significantly higher than that of both uninfected female flies. However, when choosing between infected and uninfected female bodies, there was no significant difference in the number of times they were rode by males. In other words, the female flies killed by fungi do ignite the desire of the male. As for which member of the opposite sex to express their desire, male flies may not have a special preference.

So the question is, what kind of drug is there on the body of a female fly killed by a fungus that can make the male passionate?

What is the love potion?

Scientists have noticed spore, which most fungi reproduce by forming spores.

About two hours after the death of a female fly infected with this fungus, the body begins to sprout fungal spores. 3-8 hours after death is the early stage of spore formation (sporulation), while 26-28 hours after death, it is the late stage of spore formation. The surface of the body at this time may have been surrounded by white conidia (conidia).

The team speculates that it may be the spores of fly mold that arouse the libido of male houseflies. To test the idea, they did another experiment. Put four male flies in a small room with two opaque petri dishes: conidia will fall in one petri dish and no spores will be scattered in the other.

Both petri dishes are covered with lids, but both have entrances about the size of houseflies. Scientists want to know if there is any difference in the ability of the two petri dishes to attract males, so the petri dishes are set as sticky traps so that once the males fall into the trap, they cannot get out.

As a result, in 43 experiments, a petri dish sprinkled with conidia caught all four males. In contrast, in a petri dish without spores, only 17 experiments caught four males. The data confirms scientists' speculation that fungal spores do attract males into love traps and explains why corpses a day after death are different from those three to eight hours after death.

Of course, it is not enough to do this in the experiment, and the researchers also want to know the specific ingredients of the "love potion". In other words, it is necessary to know the smell of a dead housefly infected with flies and molds. So they relied on gas chromatography-mass spectrometry (GC-MS) to see what volatile compounds were in the air.

Scientists found 24 volatile compounds in the apical space of male and female houseflies who died of fungal infections, mainly sesquiterpenes (sesquiterpenes), and ethyl octanoate was also common. Both types of substances are famous for attracting insects.

So far, scientists believe that after infecting female flies, they did create an "aphrodisiac" to attract males to have sex with the bodies of female flies. The males then become infected with the same fungus and suffer the same death blow; they end their lives at some height and leave with wings wide open, as if following the fungus's orders and trying to spread the spores more widely.

Carolyn Elya, a molecular biologist at Harvard University, said: "this study clearly shows another way in which fungi spread to new hosts." In other words, Dendrolimus can control not only infected females, but also uninfected males using chemical signals, using both ways to spread better-even in the eyes of scientists, this is a very uniqu