Carrion-eater gut bacteria help vulture bees ditch nectar for meat
A team of scientists at the University of California, Riverside is studying a species of "vulture bee" that has swapped a vegetarian diet for carrion meat by developing an extra tooth and gut bacteria similar to that found in vultures and hyenas.
We tend to think that a bee's menu is one of nectar with a side order of pollen, which isn't that far off, since bees are descendants of ancient wasps that changed from eating meat to a vegetable diet. However, in Costa Rica, there are related species of stingless bee that have reverted to meat eating and dine on carrion – possibly as a way of avoiding heavy competition for the local nectar supply.
Called vulture or carrion bees, they are remarkable not only because they're evolved an extra tooth for biting flesh, but because they also have a very unusual collection of gut bacteria. With their specialized diet, conventional bees have a mix of bacteria that hasn't changed much in 80 million years, unlike omnivorous animals like humans, which acquire new microbes with every meal. However, the vulture bees have bacteria that helps them both eat meat and protect them from food poisoning.
"The vulture bee microbiome is enriched in acid-loving bacteria, which are novel bacteria that their relatives don’t have," says Quinn McFrederick, a UCR entomologist. "These bacteria are similar to ones found in actual vultures, as well as hyenas and other carrion-feeders, presumably to help protect them from pathogens that show up on carrion."
To learn more about this, the team went to Costa Rica and set out bait in the form of raw chicken coated with petroleum jelly to repel ants. This drew not only the vulture bees, but also related species.
By studying these, the team found that the vulture bees had made other meat-related adaptations, including using the baskets on their hind legs, which are normally used to collect pollen, as what the team called "little chicken baskets" to collect the bait. In addition, the bees' microbiome possesses Lactobacillus bacteria, which ferments food, and Carnobacterium for digesting flesh.
"The weird things in the world are where a lot of interesting discoveries can be found," says McFrederick. "There’s a lot of insight there into the outcomes of natural selection."
The research was published today in mBio.