A new study found that honeybees, just like humans, spread themselves out in the hive when exposed to a common parasite — and this can help them withstand the outbreak.
When the COVID-19 pandemic first struck, the world became familiar with the words “social distancing“. While the term is somewhat unfortunate (physical distancing is probably better), it sent a clear message: staying farther away from one another can help stop the spread of this virus.
This distancing approach has been reported several times in very different types of species, from baboons that stay clear of individuals with gastrointestinal infections to ants infected with a pathogen that relegate themselves to the outskirts of the anthill. Vampire bats, mandrills, and guppies also do it. Now, this type of behavior has been reported in honeybees for the first time.
“For several years, we have been researching the behavioral defenses used by honeybees to fight parasites and pathogens. We believe that this line of research can provide useful insights to improve the health status of honeybees,” study author Alberto Satta told ZME Science. Satta works at the Dipartimento di Agraria, University of Sassari, Italy.
Bees are social creatures and they spend a lot of time huddled close to each other inside the hive. They also have complex social structures that require them to divide up responsibilities. Previous research has suggested that bees can modify their social network to limit the dispersal of a pathogen, and researchers from the University of Sassari, Italy, wanted to see if they also practice social distancing.
The researchers analyzed how honeybees changed their parasite when exposed to the ectoparasite mite Varroa destructor — one of the most common and devastating parasites bees can get.
Honeybee colonies are essentially divided into two main compartments: the inner one, inhabited by the queen, brood, and nurses, and the outer one, occupied by foragers. This distribution protects the inner circle from exposure to intruders or parasites, and there is limited interaction between the queen and the foragers that routinely go out of the hive and are more exposed — which is why they stay on the periphery.
This distribution becomes even more pronounced when bees are exposed to parasites. When a colony was exposed to a parasite, the outer circle moved even closer to the periphery, while the inner circle moved even closer to the middle.
“Our study shows that honeybees can modify their social organization in the presence of a parasite suggesting a strategy implemented to mitigate the effects of parasitosis,” Satta explained in an email.
Lead author Dr. Michelina Pusceddu, from the same university, said that this is a somewhat surprising but very efficient adaptation.
“Their ability to adapt their social structure and reduce contact between individuals in response to a disease threat allows them to maximize the benefits of social interactions where possible, and to minimize the risk of infectious disease when needed.
Developing this type of behavior takes a lot of time and is shaped by evolution, Satta adds.
“Social behaviors have evolved in animals as they increase reproductive success throughout life. In the case of honeybees and other social insects, the pattern of interactions among colony members across space and time, has evolved under the need to ensure efficient functioning, that selects dense and interconnected societies, and the exposure to parasite pressure that favors mechanisms that limit interactions between individuals to reduce the risk of disease spread. The trade-off between these two factors shapes the structure of the social organization.”
Unfortunately for honeybees, they don’t have access to the same defense mechanisms as we do — there’s no face mask or vaccine for bees. However, bees could be making their own medicine to protect themselves. Specifically, researchers are investigating the use of natural substances (propolis) with antimicrobial and anti-parasitic properties as a means to counteract the Varroa destructor mite.
“We hypothesized that bees can engage in self-medication against this parasite by using the propolis they produce in the hive. Recently, we have acquired evidence that this substance induces beneficial effects on parasitized bees, prolonging their life span, and that it has negative effects on the fitness of the mite. A further paper on these subjects will be published shortly,” Satta concludes.
The study was published in Science Advances.