When their colony is threatened by a parasite, honeybees increase social distance, according to a new study headed by an international team of researchers from UCL and the University of Sassari in Italy.
The study, published in Science Advances, showed that when honeybee colonies are infested with a dangerous mite, they alter their utilization of space and interactions amongst nestmates to increase the social gap between young and old bees.
According to a co-author from Cini UCL Center for Biodiversity & Environment Research, UCL Biosciences, they have provided the first evidence that honeybees can change their social cooperations and the way they move around in the hive when they see a common parasite.
Honeybees are a sociable species because they gain from splitting tasks and interactions like reciprocal grooming, but when such social activities raise the danger of infection, the bees look like they know how to avoid the risks by distancing themselves.
Examples of social distancing have been found in animals from very different species separated by millions of years of evolution, ranging from baboons who are less likely to clean individuals with gastrointestinal infections to ants infected with a pathogenic fungus who relegate themselves to the anthill society’s outskirts.
The current study looked to see if the presence of the ectoparasite mite Varroa destructor in honeybee colonies caused changes in social organization that might minimize parasitic transmission. Among the stressors that impact honeybees, the Varroa mite is one of the most dangerous, causing a variety of adverse consequences on bees at both the individual and colony levels, including virus transmission.
Honeybee colonies are divided into two sections: the outer one, occupied by foragers, and the interior compartment, occupied by nurses, the queen, and brood. This within-colony spatial segregation results in a lower frequency of interactions between the two compartments than those within each compartment, allowing the most valuable individuals, such as the queen, young bees, and brood, to be protected from the outside environment and thus from disease arrival.
By comparing colonies that were or were not affected with the Varroa mite, the researchers discovered that one activity, foraging dances, which can boost mite transmission, happened less frequently in the hive’s center if it was infested. Grooming activities were also observed to be more focused in the center hive. According to the researchers, in reaction to an infestation, foragers go to the periphery of the nest while the young nurse and groomer bees move to the center, increasing the distance between the two groups.
According to lead author Dr. Michelina Pusceddu, the observed increase in a social distancing between the two groups of bees within the same parasite-infested colony shows how the honeybees started to fight with pathogens and parasites.
Their capacity to alter their social structure and restrict contact between individuals in response to a disease danger allows them to maximize the advantages of social connections where possible while minimizing the risk of infectious illness when necessary.
Honeybee colonies are a great example for researching social distance and completely comprehending the usefulness and efficacy of this behavior.