Vulture Bees' Gut Bacteria Lets Them Eat Rotting Flesh

Most bees flit from flower to flower, dining on pollen and nectar. But there are some bees that prefer the allure of rotting meat.

Researchers have recently studied a stingless bee in Costa Rica that has evolved its gut bacteria to safely eat decomposing flesh. They believe the bee likely adapted to respond to increased competition for nectar.

There are only three species out of the 20,000 or so bee species in the world that exclusively eat meat, although some others will flip-flop back and forth between decaying flesh and pollen and nectar.

But rotten corpses pose some challenges to the creatures that want to eat them.

“When a carcass dies, its own gut bacteria start taking over its body and then once they start consuming the whole body, the soil bacteria come on and start fighting them. Really, it’s like this microbial warfare going on,” co-first author Jessica Maccaro, a Ph.D. student in entomology at the University of California, Riverside, tells Treehugger.

Vulture bees are able to digest the toxic microbial mix because of their gut microbes.

But honeybees, bumblebees, and stingless bees have had the same core microbiome for basically 80 million years, Maccaro says. So did something change along the way?

“The fact that they maintained that stable biome seems like the function must be important. And people have determined that a lot of those microbes are aiding in digestion of pollen and pathogen defense,” she says. “These weird bees that don’t eat pollen and that eat dead bodies instead are nested in there. Do they still have that core microbiome?”

Chicken for Dinner

To find out, researchers tied raw pieces of chicken to tree branches in Costa Rica where the bees were known to live. They smeared the chicken with petroleum jelly in hopes of keeping ants away but many other critters were intrigued by the meal.

Maccaro did most of the data analysis and didn’t get to witness the bees dining first hand.

“From what I've heard of their experience, it was super weird and crazy and a lot of other insects were going to it too,” she says. “And it was like a whole little ecosystem.”

The bees have also evolved an extra tooth for biting into the meat. Unlike other bees that use tiny baskets on their rear legs to collect pollen, these vulture bees used their baskets to collect meat. They may also swallow it and bring it back to the colony that way, only to secrete it later, Maccaro says.

“Basically, they will somehow bring it back in their bodies, spit it back out or secrete it into these little pots in their colonies,” she says.

There, they mix the meat with a little nectar or sugar source, seal it, and let it sit for 14 days to cure. They feed the protein-rich mixture to their babies to help them thrive.

“We want to look into what's happening in those pots? Is it some kind of preservation or pasteurization happening?” Maccaro asks.

Interesting Adaptations

For their research, the scientists compared the microbiomes of the vulture bees to those that feed on just pollen and some that feed on both meat and pollen. 

They found that the vulture bees had some pretty interesting adaptations to be able to eat decaying flesh, much like other carrion-feeding animals like hyenas and real vultures.

They found the most interesting and extreme changes in the microbiomes of the vulture bees. They were filled with Lactobacillus, a bacteria that is found in fermented foods like sourdough. They also had Carnobacterium, which is a bacteria able to digest flesh.

Perhaps, the researchers suggest, they create their own acid-producing bacteria to eliminate some of the microbes that cause toxins.

The results were published in the study “Why Did the Bee Eat the Chicken?” in the American Society of Microbiologists’ journal mBio.

Why Vulture Bees Matter

Maccaro, who says her lab is just interested in the microbiomes of weird bees in general, imagines these findings are important for several reasons. One possibility is the potential for antibiotic protection.

“It should be a major motivator for preserving a lot of tropical environments and the environment in general because we are running out of antibiotics. We're getting quickly resistance to a lot of them. We actually derive a ton of antibiotics from nature and so it would be really fascinating to figure out what kind of compounds these microbes are producing that are in this bees that can eat these weird things,” she says.

“I think in general, carrion-feeding animals and insects, could potentially host some really useful microbes for producing antimicrobial effects that could kind of help us with this antibiotic resistance problem.”

Beyond the scientific implications, researchers hope that just talking about an unusual species and its behaviors will help spur interest in the natural world.

“I think in general, it's important to describe whatever we can in the tropics to make people care about that, because it's such a hub of biodiversity,” Maccaro says. “The more people know and are fascinated by weird creatures, the more hopefully, they want to preserve them and their habitats.”