Don’t get into a drinking contest with Vespa orientalis hornets. They could out-booze a tree shrew, even a fruit fly. Mere humans wouldn’t stand a chance.
These hornets can survive weeks of binging on sugared liquid that’s 80 percent ethanol, researchers report October 21 in Proceedings of the National Academy of Sciences.
“To the best of our knowledge, no other animal has shown such resistance to ethanol under chronic consumption conditions,” says zoologist Eran Levin of Tel Aviv University.
Among vertebrates, tree shrews are the drink champs of species studied so far, he says. Researchers have seen no ill effects from the shrews’ days of feasting on palm flower nectar, which is naturally somewhat alcoholic. These nectars have been reported spiking as high as 3.8 percent ethanol. But in a lab, binging on 10 percent ethanol for two weeks gave the tree shrews signs of liver failure.
The V. orientalis’ powers, thus, came as a surprise. Adult hornets encounter alcohol in nectar spiked by a plant or fruits going a bit off.
Figuring out how to study drunkenness among large stinging insects doesn’t sound easy, but Levin has a weakness for “animals with a bad reputation,” he says. “I like to show why they’re important — and I always fall in love with them.”
Groups of hornets were routinely fed — and in one case, hand-fed — ethanol concentrations up to eight times higher that which fells the shrews.
One might assume the booze would send them to an early grave, but their life spans were effectively the same as teetotaler hornets. The binge-drinkers still made tidy and precise nests, and they didn’t get unnaturally aggressive when researchers mimicked intrusions.
Lab physiology tests show the hornets are actually metabolizing the ethanol extra fast. That fast detoxification ability could have arisen thanks to the abundant fermenting yeasts that are especially drawn to colonize hornet guts — a particularly good place for yeast sex.
So there’s a certian zest to the idea that yeasts helped hornets excel at detox. Hornets spreading their gut yeasts to grapes they sample may be important in creating the mysterious terroir that gives wines of particular locations their special something (SN: 9/10/20).
Coauthor and behavioral ecologist Sofia Bouchebti yearns to do more if she gets a chance. Now at Ben-Gurion University of the Negev’s Sde Boker campus in Israel, she wants to know whether ethanol changes hornet social interactions or the frequency of tending larvae. Plus, “I would have loved to study the behavior of the queens under alcohol consumption as well.”
