Researchers have enlisted a new kind of helper to monitor the microbiomes of cities around the world: the honeybee. A recently published analysis shows that the debris which gathers at the bottom of their hives can reveal a great deal about what's going on in their urban environments.
Much like our guts, cities too have microbiomes, a composite of various types of microorganisms that thrive in the environment. And, much like analyzing the microbiome in our guts can reveal important details about our physical condition, doing the same thing with a city's microbiome can reveal data about what kind of fungi, bacteria, and other small life forms are living alongside human urban dwellers.
While it's possible to use human researchers to collect data on a city's microbiome, that kind of field research can be costly, labor-intensive, and time-consuming. So researchers from New York University, MIT, Pratt Institute, and Weill Cornell Medicine decided to enlist the help of an insect that already spends its days zipping through cities all over the world: the honeybee.
Because honeybees can forage within two miles (3 km) of their hives each day, the researchers felt they could be excellent stand-ins for human field researchers. When the bees return from their hardworking days on city streets, they deposit micro debris on the bottom of the hive. By analyzing this debris, the researchers uncovered some interesting details.
In a pilot study using three rooftop hives in New York's Brooklyn borough, the researchers took hive swabs and examined honey, bee bodies and hive debris to find out which would provide the richest source of data. The debris provided the richest dataset, so the next step was to analyze debris from hives around the world.
The team found that each of the cities they looked at had different genetic signatures found in the beehive debris. In Sydney, for example, the samples showed genetic material from rubber-degrading bacteria, while Melbourne was a bit greener, with a significant amount of genetic material from eucalyptus appearing at the bottom of hives. An analysis of hives in Venice revealed that DNA from fungi associated with wood rot and date palms dominated the debris.
The analysis of the Tokyo hives not only found the DNA from yeast used to ferment soy sauce, but it also revealed the presence of Rickettsia felis, a pathogen that is spread to humans from cats, causing a condition commonly known as cat scratch fever. This finding led the team to believe that using bees to surveil urban environments might hold promise as a way to track the spread of human diseases, although they say that the current findings are too preliminary to draw a definitive conclusion on this.
"What was most surprising to us is that bees collect microbial information not only from the plants they are in contact with, but also from the microbial clouds they traverse, related to other environments or organisms," said NYU's Elizabeth Hénaff, who is lead author on the research. "This study has implications for understanding how to design our built environment to host multispecies cities.”
Additional analysis of hive debris also provided information about microbes that can affect bee health. In some hives the scientists found several microorganisms whose presence indicates a healthy hive, but in others they found pathogens that indicate the opposite, pointing to the fact that bee debris analysis could be a good way to measure the states of hives.
The research has been published in the journal Environmental Microbiome.
Source: New York University