The fungus Entomophthora muscae rightly bears its German name Fliegentöter: houseflies die quickly from the fungal infection. The victims are then often found on the windowsill, surrounded by a dusty cloud of white dots – the conidia of the fungi catapulted out of the dead insect. With these tiny forms of spread, they infect their next victim: a tube grows out of the cell clump when it comes into contact through the outer shell of the fly. But what happens if no fly gets too close? The fungus has effective ways and means to prevent this, as a research team now writes on "bioRxiv".
A few decades ago, biologists had noticed that healthy flying often does not avoid a big bow around their died conspecific. On the contrary: it happens that male house flies try to mate dead female flies to inevitably get their own flying death. The reason for the unhealthy necrophilic tendency was unclear. It was speculated that the well -rounded, bloated bodies of dead females could possibly look more tempting for the males. Henrik de Fine Licht and Andreas Naundrup Hansen from the University of Copenhagen have now found another explanation.
The researchers first tested the sexual attraction of female houseflies who died from the fungus and were not infected, but also dead because they froze to death, in petri dish arenas. Essentially, the researchers counted whether, when and which objects the males approach and how much time they take. In the end, it was clear: On fungus-infected dead, the males flew almost five times as often. Interestingly, however, the males do not distinguish between two females lying close to each other, even if one was infected and the other only froze to death. Further experiments finally showed: It is not the females at all, it is the fungal conidia that make the male flies furious.
The researchers concluded that the mushrooms have to assume a curly message that affects further distance, a kind of fungal aphrodisiac. The duo now wanted to find out what makes the attractively attractive flies. They therefore tested antennas of the males with electrodes on the fragrance of perceptive antennas, which particularly irritate the antennas from a female female. In the end, they recognized methyl -branched alkanes as a trigger. That fits well: You already knew that they increase the willingness to mate from parlors. Who knows: Perhaps the fleeting substance can also be used as a attractant for better house flying traps in the future.
