Vulture bees feed rotten flesh to their young, although it breeds toxin-producing bacteria. They are a mystery to scientists.

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

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

  • The scientists ate 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’ intestines. Acid helps vultures and hyenas digest carrion.

Hanging a piece of raw chicken from a tree is an unusual activity, even for scientists. But the researchers who were cycling through the tropical forests of Costa Rica, stringing poultry meat along branches in April 2019, were in search of an unusual insect: bees that eat rotten meat, or carrion.

Slowly, over the next five days, large bees with long slender legs approached the bait. They walked over raw chicken wraps, using special teeth to cut off pieces of meat. They collect the meat in small baskets on their hind legs, where other bees collect pollen, or they swallow the meat to store in their stomachs.

The bees were preparing to carry the chicken back to their hives, where they would put the pieces of meat into pods, leave them there for two weeks, then feed them to their babies. Scientists aren’t sure what happens inside the pods during those two weeks, or how it affects the meat. Adults do not need to eat protein. They live on nectar.

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

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

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

Wasps, however, eat fresh flesh. Disease can be a decomposing minefield, as microbes invade the body and wage “microbial warfare,” producing powerful toxins as they compete for flesh. Some of the bacteria themselves, such as salmonella, can be fatal.

“The environment around a dead body is really toxic,” Maccaro said. “That’s the big thing to overcome to be able to eat.”

That’s why Maccaro’s colleagues have been baiting and trapping these mysterious bees – to study the microbes in their guts and learn how they can eat carrion. Sure enough, the researchers found that the guts of vulture bees may be more like actual vultures or hyenas than their pollen-gathering relatives. They published their findings in Bio, the journal of the American Society of Microbiologists, in November 2021.

“The strange things in the world are where many interesting discoveries can be found,” said Quinn McFrederick, an entomologist at UCR who led the research, in a press release. “There is a lot of insight into the results of natural selection.”

Gut bacteria may help vulture bees fight pathogens on rotting meat

vultures stand in a line in grass

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

The chicken bait attracted a variety of bees – one species that collects only meat, and several species that collect both meat and pollen.

Separately, the researchers captured some bees that only feed on pollen. This enabled 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 created a much more acidic gut than their pollen-eating cousins. That could help them fight toxins that form on decaying meat.

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

Vultures and hyenas produce much of their gut acid themselves, instead of relying on microbes. But Maccaro is not surprised by the dependence of vulture bees on bacteria. Many types 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 incredibly important to bees for all these fundamental functions that we have [humans] we usually do it ourselves,” Maccaro said.

Maccaro and her colleagues hope to collect bees in French Guiana next, where they can find two of the three species of bees 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 seal them and don’t touch them for two weeks, and then they can eat the meat,” Maccaro said. “We’re really curious about what’s happening.”

This story has been updated. Originally published on November 24, 2021.

Read the original article on Business Insider

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