7:40am

Tue July 31, 2012
The Salt

Thank The Simple Wasp For That Complex Glass Of Wine

Originally published on Mon October 22, 2012 9:33 am

The next time you take a sip of your favorite wine, you might want to make your first toast to hornets. Or, more precisely, European hornets and paper wasps.

That's because those big scary flying insects whose stings can be especially painful may be the secret to the wonderful complex aroma and flavor of wine. "Wasps are indeed one of wine lovers' best friends," says Duccio Cavalieri, a professor of microbiology at the University of Florence in Italy.

Cavalieri and his colleagues discovered that these hornets and wasps bite the grapes and help start the fermentation while grapes are still on the vines. They do that by spreading a yeast called Saccharomyces cerevisiae — commonly known as brewer's yeast and responsible for wine, beer and bread fermentation — in their guts. When the wasps bite into the fruit, they leave some of that yeast behind.

Cavalieri says one of the reasons the discovery is so exciting for him is that it's an example of just how connected the natural world is and how humans rely on this interconnection in ways we simply cannot perceive.

"It's important because it's telling to me it's crucial to look at conservation and the study of biodiversity," says Cavalieri, one of the authors who published his findings in the journal Proceedings of the National Academy of Sciences recently.

"Everything is linked," he adds.

Of course, Cavalieri says, winemakers can add yeast later. But wines would not taste the same without wasps. Different yeasts applied at different times have a big impact on flavors. The wasps also introduce other microorganisms to the grapes, which add flavors to the wine.

"One of the most beautiful things of wine is the fact that basically it's complex; it's made of several parts and it communicates to several parts of your brain," he says, which could be lost without the wasps and hornets.

Cavalieri comes by his interest in wine naturally. He's from a family of winemakers in the Chianti region of Italy. He first had the inkling of hornets' special role when he saw them piercing the skin of grapes during field research in the region 15 years ago.

Insects have long helped out with wine and other crops, we just didn't know why. At least since the time of the ancient Romans, winemakers have planted flowers near their vines to lure certain insects.

The researchers were able to unwrap the mystery of the insects' role by using DNA sequencing techniques to analyze the genes of the yeast, then tracing them to the guts of wasps. They even did a lab experiment to see if hornets could pass the yeast to their offspring, and they did.

Other insects and birds also carry the yeast, Cavalieri says.But hornets seem to play a special role because they both harbor the yeast over winters and can pass them along to their offspring.

You can imagine a vineyard might be interested in pest control — but perhaps it should be careful about which bugs it considers pests.

Evolutionary biologist Anne Pringle of Harvard, who was not involved in the study, says the findings have two strong messages: Great wines need bugs and people still know almost nothing about ecology.

"If you'd like to have your grapes fermented by local yeasts, which I think many vineyards do, then you have to have these insects around," she says.

Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.

Transcript

STEVE INSKEEP, HOST:

Before the next time you take a sip of wine, you might want to make a toast to wasps. Those big scary insects play a key role in making wine, we're told. NPR's Elizabeth Shogren reports new research reveals their special function and suggests that preserving biodiversity might be more important than you think.

ELIZABETH SHOGREN, BYLINE: Years ago, Italian microbiologist Duccio Cavalieri was doing field research in the vineyards of the Chianti region, and he noticed something special about the relationship between grapes and wasps, particularly a type of wasp called the European hornet.

DUCCIO CAVALIERI: If you are looking at the berry and who was eating the berry, who could actually eat the berry were these big hornets.

SHOGREN: Other insects couldn't pierce grape skin. Cavalieri had an inkling that he was observing an important secret about wine. It took nearly 15 years and some sophisticated DNA sequencing to prove his hunch.

CAVALIERI: Wasps are indeed one of wine lovers' best friends.

SHOGREN: It turns out wasps have yeast in their bellies and they regurgitate it into the grapes they bite. Yeast is the stuff that turns grape juice into wine. The type of yeast a winemaker uses will affect the way it tastes. So the yeast in the wasps gut gets passed into the wine and imbues it with the flavor of the region.

CAVALIERI: Since the times of the Romans we have realized that it was important to improve some qualities and characteristics of the wine to have flowers and insects around the vineyard. And now we really know more about it.

SHOGREN: Cavalieri comes from a family of winemakers in the Chianti region, so he's delighted to be able to unveil one of the mysteries of wine. He published his team's results in the proceedings of the National Academy of Sciences. He says what's really important to him about his discovery is that it hints at just how interconnected the natural world is.

CAVALIERI: I think everything is linked.

SHOGREN: Those links aren't always apparent to us. Winemakers never knew that wasps were kicking off the fermentation process for them.

CAVALIERI: Yet, if we lose this, we lose complexity. And one of the most beautiful things of wine is the fact that basically it's complex, it's made of several parts and it communicates to several parts of your brain.

SHOGREN: Harvard evolutionary biologist Anne Pringle wasn't involved in the research, but she says it sends a warning to wine growers who might be inclined to use pesticides to get rid of wasps and hornets.

ANNE PRINGLE: If you'd like to have your grapes fermented by local yeasts, which I think many vineyards do, then you have to have these insects around.

SHOGREN: Pringle says there's a larger message.

PRINGLE: Personally, what this tells me is how little we know about how the world works and we're running out of time.

SHOGREN: The natural world is changing quickly because of stresses like climate change, invasive species, habitat loss and pollution. And Pringle says many species already have been lost or may soon vanish before we learn what magic they perform for Earth's ecology.

Elizabeth Shogren, NPR News. Transcript provided by NPR, Copyright National Public Radio.