Beehives Have Built-in Immune Systems

A new study has found that beehives have built-in immune systems with layers of defense that protect the colony from lethal outbreaks. The study, published in ISME Communications, analyzed 24 European honeybee colonies in New South Wales, Australia, and found that the hives were most strongly fortified against certain bacterial pathogens.

The study was conducted by microbiologist Kenya Fernandes and her colleagues at the University of Sydney and the New South Wales Department of Primary Industries in Australia. The researchers collected samples from the hives of 24 different European honeybee colonies based at five different apiaries in New South Wales, Australia.

The antimicrobial properties of honey, beeswax, and propolis are well-known, but the study found that the spatial organization of these substances in a hive, in tandem with other immune defense strategies, adds to the colony's security against pathogens like fungi and bacteria. The hives were most strongly fortified against the bacterial pathogens Paenibacillus larvae and Paenibacillus alvei, which can completely decimate a colony if left unchecked.

The study tested the antimicrobial and chemical contents of honey, propolis, wax, and pollen, as well as the microbiomes of the hive entrance, pollen, brood combs, and the guts of forager bees. The results showed that microbial communities, antimicrobial activity, and chemical composition vary predictably across hive compartments, forming a gradient from internal bee tissues to environmentally exposed hive surfaces.

## Why it matters The discovery of the built-in immune system of beehives is significant because it highlights the sophisticated social immunity of honeybees. The success of social insects relies on dense colony living, but these conditions also favor pathogen transmission. The study's findings suggest that colonies mitigate this risk through a coordinated system of behavioral, chemical, and immunological defenses. This knowledge can inform strategies for protecting bee colonies from diseases and promoting their health.

The study's results also have implications for our understanding of the importance of social immunity in protecting colonies from pathogens. As we travel closer to the hive center, the antimicrobial defenses become more targeted, with wax comb, stored pollen, and the bees' own bodies helping to filter out harmful bacteria and fungi, while encouraging helpful species. This complex system of defense is a testament to the remarkable social organization of honeybees and their ability to thrive in dense colonies.