The UCI study found that the cellophane bee ‘brew’ a liquid food for their offspring. Credit: Tobin Hammer/UC Irvine
Key points:
- Cellophane bees may hold the title of the best fermentation insect in the world.
- Lactobacilli bacteria are important for the fermentation of human food, and cellophane bees seem to use them essentially the same way.
- The unique microbiomes of these bees can provide clues to their health and ecosystem.
Scientists at the University of California, Irvine recently discovered the microbiomes of cellophane bees are some of the most fermentative known in the insect world. These bees are named for their use of cellophane-like materials to line their subterranean nests, as well as their fascinating behaviors and important ecological roles as pollinators. Now, scientists have uncovered another extraordinary aspect about cellophane bees.
According to the study published in Frontiers in Microbiology, cellophane bees “brew” a liquid food for their offspring, which are held in chambers called brood cells. The microbiome of these brood cells is loaded with lactobacilli bacteria, a substance known for its role in fermenting foods like yogurt, sourdough bread and sauerkraut. The researchers found that the food provisions of cellophane bees contain these bacteria, where they likely play an important role as a source of nutrients for developing larvae.
“It was intriguing to find that cellophane bees use a strategy called ‘spontaneous fermentation,’ which is how certain fermented foods like sauerkraut are made. Rather than passing on starter cultures from generation to generation, they use wild strains of lactobacilli that are ubiquitous in flowers,” said lead author Tobin Hammer, assistant professor of ecology & evolutionary biology and UC Irvine. “It suggests that fermentation-based symbioses like this one can evolve without domestication. What makes these bees special is that they’ve figured out how to create a favorable environment in which lactobacilli can grow really well.”
The study also found that the cellophane bees' food provision has a much higher bacterial biomass compared with other bee species. These uniquely rich, lactobacilli-dominated microbreweries could provide a better understanding of the bees, including clues to their health and the ecology of their ecosystems.
“This discovery is quite remarkable,” said Hammer. “We know that lactobacilli are important for fermentation of food, but finding wild bees that use them essentially the same way was really surprising. Most of the 20,000 species of bees get their nutrition from nectar and pollen, but for these cellophane bees, we suspect that lactobacilli are also really important. They have effectively evolved from herbivores into omnivores.”