Despite their social properties, they protect the hive from parasites through social distancing.

Honey bees are very social animals. They work with other females in brood care and also groom each other. But when social activities can increase the risk of infection, the bees hold back. “It appears that bees have evolved to balance the risks and benefits by distancing themselves,” said study researcher Alessandro Cini.

Varroa mite

In the study, scientists examined developments when the Varroa mite invaded a beehive. The Varroa mite is an external parasite that occurs on insects, but can only reproduce on the brood of honeybees. The Varroa mite is in fact one of their greatest enemies. This is because it is harmful to an individual bee as well as to the entire colony, as it transmits viruses, among other things.

compartments

Before we go any further, it’s helpful to learn more about how a honeybee colony is organized. It consists of two main compartments. The outer compartment is inhabited by the foragers, while in the inner compartment we find the nurses, the queen and the brood. This spatial separation within the colony means that there are fewer interactions between the two compartments than within the compartments themselves. And that ensures that the most valuable colony members (think of the queen, young bees and the brood) are better protected against the outside environment and therefore against the arrival of diseases.

Social organization

Of course, that doesn’t mean the inner compartment is completely safe. But to limit the transmission of diseases as much as possible, the honey bees have come up with something clever. It seems that they are changing their social organization in order to limit the spread of a parasite in the hive. “We provide the first evidence that honeybees adapt their social interactions and change their movements through their hives in response to a common parasite,” Cini said.

Dance

When the researchers compared the hive infected with the Varroa mite with a healthy hive, they discovered something special. Normally, bees communicate with each other about the location of food by dancing. But this behavior, which can obviously increase the transmission of mites, was remarkably less common in the central parts of the hive when it was infested.

Keep distance

The researchers say it appears that, in response to a pest, the foragers (the older bees) generally move more to the outer regions of the nest, while the young nurses and caretakers move toward the center. In this way, they increase the distance between the two groups. And that means that honeybees actually, just like us, keep their distance when disease threatens. “The observed increase in social distance between the two groups of bees within the same parasite-infested colony represents a new and in some ways surprising aspect of how honeybees have evolved to fight pathogens and parasites,” said researcher Michelina Pusceddu.

It means that honeybees are slightly adapting their social structure and reducing contact between individual bees, in order to minimize the risk of disease transmission. Incidentally, honey bees – and humans – are not alone in this. For example, baboons also keep their distance from infected congeners, just like mice. And even ants infected with a fungus relegate themselves to the outskirts of an anthill. It means that very different species, separated from each other by millions of years of evolution, are social distancing to do. Apparently it is a very effective rescue tool.