A unique study of urban beehives reals the secrets of several cities around the world.
Bees provide myriad benefits to humanity, including pollination services, honey production1, food security and crop pollination, artistic inspiration2 and even career opportunities3.
But what if bees could also provide insights into human and city health? A new study published in Environmental Microbiome4 shows how honey bee hives reveal information about human health, pathogens, plant life and the environment of different cities.
Our living cities
The United Nations predicts nearly 70% of the human population will reside in cities by 20505.
While cities are planned and built with humans in mind, they also act as complex, adaptive ecosystems hosting a diversity of other living organisms. Human health and wellbeing in urban areas can be affected by our interactions with the many invisible things we share our cities with.
It is therefore important to understand what biotic (living organisms such as plants, animals, and bacteria) and abiotic (non-living components such as soil, water and the atmosphere) parts make up our cities. However, to collect such samples from across the city, we need lots of volunteers, time, and intensive labour.
Honey bee hives maintained by urban beekeepers could provide a new, more efficient way to sample the urban microbiome – a collection of the local microbes, such as bacteria, fungi, viruses, and their genes.
Honey bees as collaborators
Honey bees often live in hives of 60,000–80,000 individuals6. When a bee reaches a certain age in the hive (roughly 21 days), they become a forager. Foragers leave the hive in search of nectar, pollen and other resources.
Researchers enlisted the help of honey bees as data collectors in five cities: New York in the United States, Tokyo in Japan, Venice in Italy, and Melbourne and Sydney. In urban areas, honey bee foragers typically travel approximately 1.5km from the hive to visit flowers.
During these flights they can interact with many biotic and abiotic components of the environment, carrying traces of these interactions back to the hive. In each city, the team took samples of one or more of the following: hive materials including honey, bee bodies, hive debris (accumulation of material under or at the bottom of the hive) and swabs of the hive itself.
The ‘genetic signature’ of a city
The researchers found some unexpected materials in the hives, alongside less-surprising results. Hive materials showed plant DNA that varied between cities. In Melbourne, the sample was dominated by eucalyptus, while samples from Tokyo contained plant DNA from lotus and wild soybean, as well as the soy sauce fermenting yeast7 Zygosaccharomyces rouxii.
Samples from Venice were dominated by fungi related to wood rot and date palm DNA. The samples also contained bee-related microorganisms, indicating both healthy hives and hives with pathogens or parasites, such as Varroa destructor8.
The more surprising discoveries included genetic data in the Sydney sample from a bacterial species that degrades rubber, Gordonia polyisoprenivorans. DNA from a pathogen spread to humans via cat fleas called Rickettsia felis9 was also found in samples, and showed up in Tokyo hives over time.
How do we interpret these results?
The study offers a new and interesting use of honey bee hives in cities – the potential to monitor human health and urban pollution. However, there were some limitations to the work. The differences in microbiomes across cities were based on small sample sizes – one hive in Venice, three in New York, two in Melbourne, two in Sydney and 12 in Tokyo.
Due to these constraints, differences between cities could potentially be attributed to variation in hives and their genetics. Future work using longer-term studies with more hives would help to uncover whether the unique genetic signatures were due to differences amongst cities or between hives or even time periods.
The authors have suggested that honey bee hive debris could provide a snapshot of the microbial landscape of cities. In the future, they argue such methods could even help to monitor antibiotic resistance and the spread viral diseases, but much more sampling and validation will be needed to achieve these goals.
*Article By Scarlett Howard
References:
https://theconversation.com/curious-kids-how-do-bees-make-honey-143450
https://theconversation.com/the-farmer-wants-a-hive-inside-the-world-of-renting-bees-94904
https://www.biomedcentral.com/articles/10.1186/s40793-023-00467-z
https://www.science.org.au/curious/earth-environment/honeybee-hive
https://theconversation.com/explainer-varroa-mite-the-tiny-killer-threatening-australias-bees-25710
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3168219/
Dr Scarlett Howard is a lecturer and research group leader in the School of Biological Sciences at Monash University. Her research spans cognition, behaviour, pollination, ecology, zoology, neurobiology, environmental change, and bio-inspired solutions. She predominantly works with bees and other insects to explore the cognitive abilities of miniature insect brains. Her work on honeybee cognition and pollination spans between collaborations across the world. Scarlett has previously worked at the Centre for Integrative Ecology (CIE), School of Life and Environmental Sciences at Deakin University, the Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication at RMIT University, the School of BioSciences at the University of Melbourne, the Experience-Dependent Plasticity in Insects (EXPLAIN) Team in the Research Center on Animal Cognition (CRCA) with CNRS - Université Toulouse III - Paul Sabatier (Toulouse, France).
