Why Fruit Flies Love Beer
Researchers from KU Leuven, VIB and NERF have pinpointed what makes the fruity aroma produced by yeast cells so attractive to fruit flies – and why it could be beneficial to the yeast cells’ survival. Writing in the journal Cell Reports, the researchers say yeast cells in beer attract fruit flies as a means to ‘hitch a ride’ to new food sources and ecosystems.
It turns out yeast cells do more than just make your beer taste good.
Using a combination of molecular, behavioral and neurobiological tests, the researchers isolated a gene in yeast cells – ATF1 – responsible for producing acetate esters, the pleasing fruity and flowery aromas characteristic of fermented beverages like beer and wine.
When the researchers switched off this gene in the yeast cells, the flies were much less attracted to the food source.
Moreover, the researchers found that the antennal lobe in fruit flies’ brain becomes excited when exposed to yeast cells with a normal ATF1 gene, while this was not the case for yeast cells with a suppressed ATF1 gene. This suggests that fruit flies’ brains are wired to seek out acetate esters, say the researchers.
The results offer new insights into the “intricate mutualism” between stationary microbes like yeast cells and flying insects like fruit flies.
The production of aromas “help alert flies to the presence of yeast cells, a vital component of their diet. Whereas some of the yeast cells are consumed by the insects, a fraction of cells will stick to the fly body and get dispersed to a different environment,” write the authors in the paper. For the yeast, dispersal is essential to reach new niches, especially when nutrient levels are running low.
“It seems that the same flavors that we enjoy in our beer probably evolved to attract flies and to help yeast disperse into broader ecosystems,” says Emre Yaksi (NERF – VIB/KU Leuven), a neuroscientist and co-author of the paper.
The researchers say the study adds to our understanding of the complex physiological role of aromas. “We all know that flowers attract insects by producing aromas. But there are also many microbes living inside flowers, and the chemicals they produce may also play an important role,” says Joaquin Christiaens (VIB/KU Leuven), another co-author.