That is because when honeybees go foraging, they collect more than just pollen and nectar. As they navigate through their environment, micro-organisms and other tiny particles can also cling to the bees’ fuzzy little bodies, which the pollinators then shed as they enter their hives.
And since pollinators tend to forage within about a kilometre radius of their hives in urban areas, there is valuable information about a city or even a neighbourhood in the honey they produce, on their bodies and in the debris that lies at the bottom of hives.
“Honeybees will gather a vast number of microbes day to day, far beyond things they are seeking out. They’ve been optimised by evolution to do everything that the swabs do,” said Kevin Slavin, a professor at MIT Media Lab, during a press briefing on a new report in the journal Environmental Microbiome. The new research aims to establish a feasible method for collaborating with beekeepers and their colonies of honeybees for the purpose of studying the microbiome of cities.
A microbiome is the unseen communities of microbes, fungi, viruses and bacteria that live inside and around us, playing a key role in the functioning and health of the urban environment and the human population, as well as plants and animals. Previous research has linked exposure to a diverse microbiome to better health outcomes.
In the near future, understanding microbial environments can become crucial to understanding the many ways in which health and environmental inequalities disproportionally affect marginalised communities, said Slavin. “We tie that, currently, to things like pollution or even shade, [but] the idea is in part just to collect as much data as we can, far beyond straightforward pathogen screening, to better understand what produces healthier neighbourhoods, and can it be measured.”
To test if bees can be used to “swab” the city, Slavin and a team worked with local beekeepers to collect and analyse microbes from samples of honey, honeybee parts, and debris from hives across five global cities — New York, Venice, Tokyo, Melbourne and Sydney — using the information to uncover insights about the unique and diverse microbial footprint of each place.
The study began in New York City, where researchers compared microbes from three different neighbourhoods — two in Brooklyn and one in Queens — to show how microbes might differ from one neighbourhood to another. They were able to find a diversity of species, including bacteria associated with plants and the larger environment, as well as human-related pathogens. The material gathered from hive debris varied the most among the three locations.
What honeybees in South Africa need from people: better managed forage
Meanwhile, in Venice, where many buildings sit atop wooden pilings submerged in water, sample data consisted of fungi related to wood rot, for example. And in Tokyo, the researchers found genetic traces of a fermenting yeast used in the production of soya sauce and miso paste.
“Cities have their own microbial signatures, which are also interestingly related to the cultural and geographical context in which those cities have emerged,” said co-author Elizabeth Hénaff, a computational biologist at the New York University Tandon School of Engineering. “It didn’t feel like a disjointed metric from all of the other things that we know about these cities,” she added. “It actually kind of felt like a puzzle piece that we didn’t even know existed.”
More than that, the study demonstrated how the materials gathered from beehives could potentially aid health officials in pathogen surveillance. Using multiple samples collected from Tokyo, researchers were not only able to identify the pathogen Rickettsia felis — responsible for the bacterial disease known as “cat scratch fever” — but do further analysis to determine the genetic factors that enable it to infect its hosts.
There are multiple methods for studying the microbiome of a city, including testing wastewater, which has been used to detect the presence of drugs and more recently to understand the spread of Covid-19 in communities. But the researchers say that method focuses on things that humans have processed.
“What about the city or a neighbourhood as a whole?” said Slavin. “What about everything that isn’t processed by humans?”
