海角大神

Whether a male bee finds a mate or not might depend on how he buzzes.聽

Female red mason bees check out a male鈥檚 vibrations, but not just for strength and health. Like an accent, a buzz can reveal where the male is from.

And, according to a new study,聽the females prefer to mate with .

In a paper published Thursday in the journal聽Current Biology,聽scientists observed the mating habits of red mason bees from Germany, England, and Denmark.

鈥淲e knew from previous studies that the female bee, in the red mason bee that is, uses vibrations to pick a male,鈥� study author Taina Conrad of the Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm聽tells 海角大神 in an interview. But 鈥渘ow we found that they actually use it not just as , which is a basic signal, but somehow, somewhere in this signal is also encoded where the male comes from.鈥�

Among red mason bees, mating is ladies鈥� choice, with the females accepting or denying a male鈥檚 advances based on mating behavior. When the males were from their own country, the females overwhelmingly accepted them, with a success rate of about 90 percent.聽

But when bees from a different country tried to mate, the female rejected them most of the time. These combinations had success rates as low as 20 percent.

When a male red mason bee tries to mate with a female he must first woo her through mating behaviors. First, he will hop on her back. Then, 鈥淗e waves his front legs and his antennae in front of the female鈥檚 eyes and antennae,鈥� describes Dr. Conrad. 鈥淢eanwhile, he produces these vibrations that we were looking at.鈥�

The bee uses his wing muscles to create these vibrations, signaling his physical fitness and apparently his homeland.聽

鈥淗e does that for a while and then he tries to copulate with the female,鈥� explains Conrad. 鈥淭he female either lets him copulate, or she throws him off if she doesn鈥檛 like him.鈥� The female can also bend away from the male if she doesn鈥檛 like him, although he will try to woo her again if he is still on her back.

The researchers first observed bees attempting to mate with bees from their own country and from others. They kept track of the success rates, and measured and recorded the bees鈥� vibrations.聽

Using these recordings, the researchers were able to eliminate other potential signals of a bees鈥� home country.聽

鈥淲e thought, ok those vibrations might be how they differ between the different countries and they might be the reason why the females choose one male over another. But in order to actually know that, you would have to change the vibrations in a live bee,鈥� Conrad says. For example, in a 鈥淕erman male change the vibrations so he sounds or rather feels like an English male.鈥澛�

鈥淭hat actually is a lot more difficult than you would think, because they sit on top of each other,鈥� she says.

But the researchers were able to find a way around that challenge.聽

鈥淲e wanted to find a non-invasive way to change their vibrations,鈥� Conrad says. So what better way than to glue tiny magnets to the bees鈥� backs?

Courtesy of Taina Conrad

This male red mason bee has a tiny magnet glued on his thorax so scientists can change the vibrations he makes during mating behavior.

Conrad and the other study author, Manfred Ayasse,聽placed each pair of male and female bees on an inductor. 鈥淭he inductor was connected to an amplifier and a frequency generator,鈥� says Conrad. Then, she entered the signals, known from recording bees鈥� actual vibrations, in the frequency generator. That vibration pattern was transferred to the inductor, creating an electromagnetic field.聽

Through that electromagnetic field, Conrad was able to make the magnet vibrate. 鈥淔ortunately the males feel that and stop their own vibrations, but they continued their other mating behavior,鈥� she says.

鈥淎mazingly, this worked really really well and suddenly the females like to mate with the males they hadn鈥檛 liked before," says Conrad. 鈥淚f you change the language, so to say, and now they speak the right language, she will mate with him again. To us that鈥檚 just proof that it really is something in the vibrations, because we didn鈥檛 change anything else.鈥�

Courtesy of Taina Conrad and Current Biology

A pre-copulatory pair from different countries was placed on the iron core within the inductor. The signal of a successful male, produced by a frequency generator and then amplified, was then transmitted onto a magnet on the male's back via the electromagnetic field. This method increased the success rate of mating between bees of different origins.

The researchers even tried the opposite: making a male from the same country as the female vibrate as though he were from another country. The mating success rate plummeted. It was all about the vibrations.

Why don鈥檛 females want to mate with males from other places?

鈥淲e believe that that could be because of local adaptations that they might have, for example, the bees from Germany might be adapted to the climate in Germany or the flowers that they find here,鈥� Conrad says. The offspring produced with a male without those adaptations would likely be less successful.

Okay, but why do we care about bees in the first place?

Bees are crucial pollinators of many crops. This agriculture supports much of the world鈥檚 food supplies. Understanding how bees mate can help maintain this vital population.聽

Conrad says she likes to quote Albert Einstein, or at least a phrase attributed to him.聽鈥淗e was that if the bees disappear from the world, then man would only have four years of life left. No more bees, no more pollination, no more plants, no more animals, no more man.鈥�