Why beetles fly on beer

Mushrooms grown by ragweed ferns thrive best in an alcoholic environment

Not only are we looking forward to a cold beer - Ambrosia beetle also attracts the smell magically. © m-gucci / istock
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Seduced by beer: Researchers have discovered why some beetles attract alcohol. According to this, the mushrooms bred by insects from the large group of ragweed beetles thrive particularly well in an alcoholic environment. Beer and co fragrance for the beetles therefore after good harvest, rich food - and a lot of offspring. So it is hardly surprising that the little ones always get lost in our beer and wine glasses.

With the first nice days bother us annoying pest spirits: As soon as we have sat down with a refreshing after-work beer in the garden, even tiny beetles dive into our glass and enjoy the alcoholic beverage. Often, these are so-called ambrosia beetles - a group of insects that produce several thousand species of fungi that breed and feed themselves and their offspring with the help of these microorganisms.

"It has been known for some time that sick, dying trees produce alcohol and that the beetles recognize and prefer to colonize these trees, " says Peter Biedermann from the University of Würzburg. "Traps of alcohol are a proven method of attracting and capturing insects." But where does the beetles love for beer and co?

Ambrosia beetles create tunnel systems in dying wood in which they grow mushrooms. © Gernot Kunz

Living in the per thousand range

This question has now been investigated by the scientist and his colleagues. They wanted to know if alcohol might play a role in the fungal farms that plant species such as the black wood bark beetle (Xylosandrus germanus) in their living tubes in wood. They found out: The mushrooms bred by the two millimeter small beetle seem to thrive optimally in alcohol-rich environments.

Because while the substance is toxic to other microorganisms, these fungi have particularly active alcohol-degrading enzymes - and are perfectly adapted to a life in the per thousand range thanks to them. The mushrooms grow best at alcohol concentrations of about two percent, as the researchers report. display

Good harvest thanks to alcohol

With this content, therefore, a good harvest is guaranteed, but the mushroom species are not overgrown. No wonder, therefore, that the cubs fly on alcohol: For them, the substance smells like a rich supply of food and that in turn means more offspring.

The agricultural system of the K fer is so complex that the animals even bring the "seeds" for their gardens when they colonize a new tree: they transport fungal spores in special organs of their bodies. Conversely, the mushrooms also ensure success: they can produce alcohol themselves and thus optimize the conditions for their growth, as Biedermann and his colleagues report.

"The fungi cultured by the ragweed behave like beer or wine yeast: they generate an alcoholic substrate in which only they can thrive and of which other microorganisms have nothing, " explains Biedermann. But how do the people manage to survive in such an exhilarating environment? "Of course they have to be more resistant to alcohol than other beings, " says the researcher. In the future, the team wants to explore more closely how the Winzlingen will succeed. (Proceedings of the National Academy of Sciences, 2018; doi: 10.1073 / pnas.1716852115)

(University of W rzburg, 10.04.2018 - DAL)