Carnivorous vulture bees evolve to feast on meat

(CNN) — The vast majority of bees feed on pollen and nectar, but certain species have evolved to feast on meat, replacing flower meadows with carcasses of dead animals.

To better understand this extreme change in diet, scientists from the University of California-Riverside, Columbia University and Cornell University studied the intestinal bacteria or the microbiome of so-called vulture bees in Costa Rica.

The researchers found that the guts of bees are rich in acid-loving bacteria similar to those found in vultures, hyenas and other carrion-eating animals.

Their study was published Tuesday in the journal mBio, published by the American Society for Microbiology.

Only three species of bees in the world, all vulture bees, have evolved to obtain their protein exclusively from dead meat, and they live only in rainforests. However, there are other species of bees that will consume fresh animal carcasses when available, but will also search for pollen and nectar, according to the study.

Bees and gut bacteria

The guts of honey bees, bumble bees and stingless bees are colonized by the same five core microbes, and have retained these bacteria for about 80 million years, the study noted. The researchers wanted to find out how the guts of vulture bees were different.

The scientists set up 16 stations baited with 50 grams of raw chicken hanging from branches about 1.5 meters above the ground. To deter ants, they covered the rope with petroleum jelly.

They collected 159 bees in total, including, for comparison, bees that feed on pollen and meat and vegetarian bees that feed exclusively on pollen and nectar.

After studying the bees’ microbiomes by extracting DNA from their abdomens, the researchers found that the vulture bees had lost some of the core microbes that most bees have and developed a more acidic gut.

“The vulture bee’s microbiome is enriched in acid-loving bacteria, which are new bacteria that its relatives do not have,” said Quinn McFrederick, assistant professor and bee specialist at UC Riverside and author of the study.

“These bacteria are similar to those found in royal vultures, as well as hyenas and other carrion-eating animals, presumably to help protect them from carrion-borne pathogens.”

He added that bees that feed on both pollen and carrion had different types of bacteria compared to strict pollen feeders or strict carrion feeders.

This suggests that they harbor a greater diversity of microbes in response to their diverse diet or that they are exposed to a greater diversity of microbes when they visit both flowers and carrion.

One of the bacteria present in vulture bees is Lactobacillus, which is found in many fermented foods from humans, including sourdough, according to a press release.

They were also found to harbor Carnobacterium, which is associated with the digestion of meat.
Although they eat meat, the researchers said that the honey from the vulture bees is still sweet and edible.

“They store the meat in special chambers (in their hives) that are sealed for two weeks before accessing it, and these chambers are separate from where the honey is stored,” said Jessica Maccaro, a doctoral student at UC Riverside who also participated. in the study, in the statement.