When they start life, honey bees hatch and grow up inside their hive with roughly 40,000 other bees, and for their first three weeks of life, this dark, constantly buzzing home is all they know. After this crucial development period, they venture out of the nest in search of nectar and pollen—a moment of considerable risk but great reward. This moment is also when young bees become recognizable by other, older honey bees, as per new research recently published by the online journal eLife.
Basically, according to researchers, honey bees have scent profiles that differ based on their age, and gatekeeper bees react differently toward returning forager bees than when they come upon younger bees who’ve never been outside the hive. This research provides new insights into a crucial period in the lifecycle of these social insects. Until now, most researchers believed bees recognized and responded to the homogenized scents of every bee in their colony, given that’s at least the case for several ant species and similar insects.
However, new research from Yehuda Ben-Shahar, who is an associate biology professor with Washington University’s School of Arts & Sciences, shows nestmate recognition is based on an intrinsic developmental process that’s linked to age-dependent labor division. “It was always assumed that the way honey bees acquire nestmate recognition cues, their cuticular hydrocarbon (CHC) profiles, is through these mechanisms where they rub up against each other, or transfer compounds between each other,” says graduate student Cassondra Vernier, who was this study’s first author. “You would expect then that even younger bees would have a very similar pheromonal profile as older bees—when in fact that is not what we saw.”
For this study, Vernier compared CHC profiles from bees of different ages, including three weeks, two weeks, one week, and newborn. The three-week-old honey bees had very different profiles compared with the younger bees. Three-week-old foragers also have very different jobs than younger bees—ones who spend their time as nurses caring for honey bee larvae while also building the hive’s honeycomb structures. Vernier’s team wanted to know whether these noticeable differences were just from age or were because of the older honey bees’ foraging duties. Bees exiting a hive to gather nectar encounter many scents from plants and other things they touch. They’re also exposed to various environmental factors, including rain and sunshine, which could affect body coatings.
With that, Vernier compared CHC profiles from foraging-age honey bees held inside the hive but were not allowed to forage outside with other bees who could, and these groups also proved to have significantly different scents. “What we found is that it’s actually a combination of both—of being at the age for foraging and actually performing the foraging activities,” Ben-Shahar said.