Allogroomers are worker honeybees that specialize in grooming their hive mates. A new study by UCL and University of Florence, published in Scientific Reports, shows that groomer bees play a central role in the health of the bee colony by warding off pests. They are connected to more bees colony-wide than an average bee, which allows their grooming habits to benefit many bees and keep the colony as pest-free as possible. Bee grooming provides collective immunity.
Allogrooming is performed by worker bees with stronger immune systems which may enable them to withstand higher infection risks. Grooming bees are exposed to elevated risks of contracting parasites and pathogens, so it was remarkable when researchers tested their immune systems and found that their hemolymph, which is like blood but for insects, was capable of more effectively clearing out potentially harmful bacteria than the immune systems of other bees in the colony.
This 2:10-minute video shows some groomer bees in action:
Co-author of the study, Dr. Rita Cervo from University of Florence, stated that by identifying a striking difference in the immune systems of the allogrooming bees, which are involved in tasks important to colony-wide immunity from pathogens, they found a link between individual and social immunity.
Groomer bees use their mouths to remove debris, including parasites and other pathogens, from the body of another bee in the colony. Scientists think that if more bees engaged in allogrooming behavior, it may impart greater immunity on the whole colony. This can be especially helpful against ectoparasites, like Varroa destructor mites that live on the outside of a host’s body, as these are a growing threat to honeybees globally. Allogrooming may be an effective pest control strategy and it helps boost colony immunity. These specialized bees are the most connected in the social network in the hive.
Worker bees are the true “busy bees” in any bee colony and they are assigned different activities within the community at different stages of their lives. Allogrooming is one of these specialized jobs, but until now it wasn’t noted how specialized the groomer bees are and how their physiology may be different.
This study focused on Apis mellifera, the western honeybee, which is also the most common species of honeybee. It is the bee that is most used in industrial agricultural pollination and honey production.
Researchers found that allogrooming is a relatively weak and transient specialty because the groomer still devotes time to other tasks just like other worker bees. This shows that bees can develop physiological differences that are narrowly tailored to specific tasks while being able to adapt to other tasks in the moment.
The allogroomer bees did not have more finely tuned antennae, so they were not tuned in to relevant odors that might alert them to which bees needed grooming. Researchers are considering that they can detect who needs grooming in other ways, for instance by noticing the ‘grooming invitation dance’ which is when bees shake their entire body from side to side. More research will follow.