It appears that honeybees voluntarily enter ‘lockdown’ mode when they become aware that a parasite has entered their hive. They willingly comply with various measures to try to isolate and thereby eradicate the invader.
Researchers at UCL and the University of Sassari, Italy recently led an international team in a new study that concluded honeybees naturally and instinctively know to increase social distancing when their hive is under threat from parasites. Their study was published in Science Advances.
Honeybee colonies respond to an infestation of mites by altering the way they interact with their hive mates. There is more social distance maintained between young and old bees.
According to study co-author Dr Alessandro Cini (UCL Centre for Biodiversity & Environment Research, UCL Biosciences), the team has provided first evidence that honeybees modify their social interactions and the way they move around their hives when confronted with a common parasite.
The honeybee is a social animal, Dr Cini explains. They assign responsibilities and interactions like mutual grooming, but if these social activities might increase the infection risk, the bees seem to have evolved in a way that they balance the risks and benefits by social distancing.
Social distancing has been observed in such very different animal species as baboons that are less likely to clean individuals with gastrointestinal infections, and ants that relegate themselves to the suburbs of anthill society when infected with a pathogenic fungus.
The new study evaluated whether the presence of Varroa destructor mite in honeybee colonies caused changes in social organization to reduce the spread of parasites. The Varroa mite is one of the honeybees’ main enemies as it causes virus transmission and other harmful effects on single bees and at a colony level.
The honeybee colony is organized into two main areas: the outer part is occupied by foragers, and the inner area is inhabited by nurses, the queen, and the brood. This inside-colony separation allows for a lower frequency of interactions between the two compartments, so those in each compartment have less interaction. It allows the most valuable bees (queen, young worker bees, brood) to be protected from external environmental issues like the arrival of diseases.
This unrelated 4:07-minute video by Brut America discusses the social distancing of honeybees:
The researchers compared colonies that were and were not infested by Varroa mites. Such behaviors as foraging dances, which can increase mite transmission, occurred less frequently in central parts of an infested hive. Grooming behaviors also became more concentrated in the central hive. Researchers said it seems that in general, foragers (older bees) move to the periphery of the nest while young nurse and groomer bees move to the center when there is an infestation, to increase distance between them.
According to lead author of the study, Dr Michelina Pusceddu (Dipartimento di Agraria, University of Sassari), increased social distancing between the two groups of bees in the same parasite-infested colony shows a new and surprising way honeybees have evolved to combat pathogens and parasites.
Adapting their social structure and reducing contact between individuals in response to a disease threat lets bees maximize the benefits of social interactions and minimize the risk of infectious disease as needed. She said honeybee colonies are an ideal model to study social distancing and to understand the value and effectiveness of this behavior.
The study involved researchers from UCL, the University of Sassari, the University of Turin, and the Martin Luther University Halle-Wittenberg (Germany).
Those interested in reading the study results can click here.
Perhaps humans can learn something about social distancing from observing honeybees.