The bees that eat corpses

Introduction

Thanks to Babbel, a language learning app, for sponsoring this episode. If you’re interested in growing your language skills in the new year, SciShow viewers get up to 65% off when you use our link. Whether you love them or you run away screaming from them, we can all agree that bees are beneficial little critters. They pollinate flowers, perform a charming little waggle dance, and even help corpses decompose. Yes, you read that right, corpses. But don’t worry, not all bees do this, so there’s no need to look suspiciously at the jar of honey on your kitchen counter. This is mainly a vulture bee thing.

Vulture Bees

Vulture bees make up three species of bees in the genus Trigona, and they live in the rainforests of South and Central America. Like honeybees, vulture bees are social hive-dwellers. They are also obligate necrophages, which means they eat mostly carrion or dead things. This is not the sort of cuisine that most bees tend to be into. Though it’s worth mentioning that some bees forage for both pollen and carrion. And vulture bees are not strictly carnivorous, either. They do also get carbohydrates from plant sources like fruit. And they hunt wasp larvae because they weren’t hardcore enough already, I guess. But one thing they will never do is visit a flower. They prefer a nice steak.

Bees and Corpses

The bees find a corpse, strip it, and bring the meat back to the hive. After that, it’s not really clear what happens, but it’s probably not a barbecue. Instead, the bees store the carrion away… to do something. The bees might use the meat to produce hypopharyngeal gland secretions, which is what honeybees use to make the royal jelly that feeds the queen and her young. They might also use it to make corpse honey. Which I’ve heard is just great on a sourdough toast.

Evolution of Vulture Bees

Vulture bees evolved fairly recently from pollen-eating ancestors. It’s definitely possible for an animal to make this kind of dietary 180, but in order for it to work, something unusual has to happen in the gut microbiome, the community of microbes that lives in the animal’s gut. It is believed that all bees are descended from a common ancestor that had five major types of microbe in its gut. And most bees still have all five. These microbes serve distinct jobs, like helping break down toxic sugars that can sometimes be found in pollen.

Microbiome of Vulture Bees

The authors of a 2021 study wanted to find out how the microbiome of pollen-eating bees compared to the microbiome of vulture bees. They found that vulture bees still have some of those same microbes. But not all of them. And they have new ones, too. Unsurprisingly, they have microbes that are strictly for meat eating. But not as many as researchers expected them to have. They also have some of the same microbes pollen-eating bees have.

Microbes Adaptation

This might mean that the microbes adapted to the carrion diet as the bees did. But, it might also mean that those microbes were doing something unrelated to diet in the first place. For example, certain microbes in the microbiomes of other insects may help protect their host from disease by preventing the overgrowth of pathogenic bacteria. It’s not really clear, though, how the change in microbiome happened. It’s kind of a chicken and egg thing. Like, whether the bacteria changed first, and that made the change in diet possible. Or whether the microbiome changed because the bees’ diet changed.

Conclusion

And vulture bees, like all bees, are descended from meat-eating wasps, so in the end these bees are kind of just getting back to their roots. And the about-face in their gut microbes can tell us a lot about how the microbiome adapts to changes in diet. Not bad for the makers of corpse honey.