The prevailing view when it comes to the development of honeybees' social status is that what they eat as larvae determines whether they will become the fertile queen or one of the sterile workers. Now researchers are close to understanding just how honeybee diets affect their future roles in the colony.
Honeybee queens and her workers are genetically identical, and yet there is a clear distinction in both physical size and function in the colony. Queens are capable of reproducing, whereas the workers are sterile, and queens have a tendency to live longer than her workers.
How does one become the queen bee in the colony? Researchers have been trying to uncover that mystery, but the long-held belief is that what they eat during the larval stage of their lives determines their future fate.
Essentially, bee larva fed with beebread turn into sterile worker bees, whereas bee larva fed with royal jelly turns out to be queens. What's the difference? Beebread is plant-based and is a mixture of pollen and nectar, while royal jelly is secreted by the other bees.
Plant-Based And Animal-Based Food
This isn't the first time that this team of researchers studied the caste development of bees. In a previous study, they found that the ingestion of plant and animal-based food yields different gene expressions during development, mainly due to miRNA.
To understand that further, the team collected beebread, pollen, honey, and royal jelly from hives and measured their miRNA levels. Molecules called miRNA are small RNA molecules, which regulate genes. In plants, miRNA helps in making flowers and leaves.
What they found was that beebread actually had much higher levels of miRNA compared to royal jelly, and the larva that they reared in the laboratory with beebread mimic ended up as worker bees with smaller ovaries. They were also smaller in size and lighter in weight.
Upon studying the miRNA in beebread further, researchers found that 16 most abundant miRNAs are actually capable of binding themselves to 96 bee genes, affecting development. In particular, they determined miR162a, which inhibits the development of amTOR, an active gene among queens.
Interestingly, none of these inhibiting effects were seen in royal jelly. However, when researchers gave the larva only miR162a, development was not significantly prolonged, which means that miR162a isn't the only miRNA responsible for the development delay among worker bees.
Authors of the study point out that perhaps since beebread is plant-based, it could be an evolutionary tool that plants and flowers use to develop workers that will pollinate them. However, other experts believe that this merely points to miRNA as a significant part of signaling diet quality.