‘Vulture bees’ feed their babies on rotting flesh, even though it breeds toxin-producing bacteria. They are a mystery to scientists.

vulture bees crawl on a piece of raw chicken hanging in the jungle

Vulture bees in Costa Rica dine on raw chicken bait.Quinn McFrederick/UCR

  • “Vulture bees” feed their larvae rotting flesh instead of relying on pollen like other bees.

  • Scientists hung raw chicken in Costa Rica and watched vulture bees fill their leg pouches and stomachs with it.

  • They found acid-producing microbes in the bees’ guts. Acid helps vultures and hyenas digest carrion.

Hanging pieces of raw chicken from trees is an unusual activity, even for scientists. But the researchers who cycled through the tropical forests of Costa Rica in April 2019, stringing poultry meat along branches, were chasing an unusual insect: bees that eat rotting meat or carrion.

Slowly, over the next five days, large bees with long, dangling legs flocked to the bait. They crawled over the folds of raw chicken and used special teeth to cut off pieces of meat. They collected the meat in baskets on their hind legs, where other bees collect pollen, or swallowed the meat to store it in their stomachs.

The bees were preparing to return the chicken to their hives, where they would stuff the pieces of meat into pods, leave them there for two weeks, and then feed them to their babies. Scientists aren’t sure what happens in the pods during those two weeks, or how it affects the flesh. The adults do not need to eat protein. They survive on nectar.

The bees with leg baskets also still collect pollen for their babies. Only three species – of the more than 20,000 known bee species – feed their larvae on an entirely carrion-based diet. They are called “vulture bees”.

These bees are “super crazy on a number of different levels,” Jessica Maccaro, a doctoral student in entomology at the University of California, Riverside (UCR), told Insider.

“The easiest way to think about bees is that they’re vegetarian wasps. They evolved from wasps. Literally what sets them apart from wasps is that they’re vegetarian,” Maccaro said. “So this is really surprising.”

However, even wasps eat freshly killed meat. Rotting flesh can be a minefield of disease as microbes take over the body and wage “microbial warfare,” producing powerful toxins as they compete for flesh. Some bacteria themselves, such as salmonella, can be deadly.

“The environment on a corpse is really toxic,” Maccaro said. “That’s an important thing to overcome in order to eat.”

That’s why Maccaro’s colleagues were busy luring and capturing these mysterious bees – to study the microbes in their guts and learn how to eat carrion. Sure enough, the researchers found that the guts of vulture bees may look more like real vultures or hyenas than their pollen-gathering relatives. They published their findings in mBio, the journal of the American Society of Microbiologists, in November 2021.

“The weird things in the world are where a lot of interesting discoveries can be made,” Quinn McFrederick, an entomologist at UCR who led the research, said in a news release. “There’s a lot of insight there into the results of natural selection.”

Gut bacteria can help vulture bees fight pathogens on rotting flesh

vultures line up in the grass

A committee of vultures meets for scavengers at the Ol Pejeta Conservancy in Kenya, October 3, 2020.Edwin Waita/Reuters

The chicken bait attracted a range of bees—one that collects only meat, and several that collect both meat and pollen.

Separately, the researchers also caught some bees that only feed on pollen. This allowed them to compare the guts of carnivorous, omnivorous and vegetarian bees.

The microbes in those guts were very different. The vulture bees had a lot of acid-producing bacteria like lactobacillus, which probably created a much more acidic gut than their pollen-eating cousins. That can help them fight toxins that build up on rotting flesh.

“These bacteria are similar to those found in real vultures, as well as hyenas and other scavengers, presumably to help protect them from pathogens that appear on carrion,” McFrederick said in the press release.

Vultures and hyenas produce a lot of acid in their guts themselves, rather than relying on microbes. But the vulture bees’ reliance on bacteria comes as no surprise to Maccaro. Many species of bees use microbes to line their guts, protect them from parasites and break down their food.

“We can already see that the microbiome is super important to bees for all these basic functions that we [humans] usually we just do it ourselves,” Maccaro said. “So this is another case, where they’re using their microbiome to create this acidic environment instead of doing it themselves.”

Maccaro and her colleagues next hope to collect bees in French Guiana, where they can find two of the three bee species that only collect carrion. They want to study what happens in the pods where the vulture bees store meat before feeding it to their larvae.

“They store them and they seal them and they don’t touch them for two weeks, and then they can eat the meat,’ Maccaro said. ‘We are very curious to see what happens.’

This story has been updated. It was originally published on November 24, 2021.

Read the original article on Business Insider

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