In the’East Lawn Cemetery, (Ithaca, New York State, USA) lives a bee colony of approximately 5.5 million individuals: it is one of the largest and oldest aggregations of ground-nesting bees ever recorded in the world, equivalent to over 200 honey bee hives in a 1.5-acre plot of land (less than 61 thousand square metres), over three times the population of Manhattan.
How the incredible discovery happened
Rachel Fordyceentomology laboratory technician on the campus of Cornell Universityparked his car for free atEast Hill Plaza Of Ithaca and walked across theEast Lawn Cemetery This way he can get to his workplace while saving money on the nearest paid parking.
But one spring day in 2022, he showed up to work with a jar full of bees, reporting that an area of the cemetery was full of bees. Together with his professor, Bryan Danforthand the rest of the research team, identified the specimen as Andrena regularis (also known as ‘Common miner bee‘), a wild, solitary species that nests in the ground and is an important pollinator.
Even if the professor initially claimed that it was not a big news, considering the cemetery full of bees for some time, in reality the colony housed there was not exactly common: the jar of bees from Fordyce in fact, it led to the discovery of one of the largest and oldest aggregations of ground-nesting bees ever recorded in the world, with an estimated 5.5 million specimens.
I am sure that there are other large aggregations of bees around the world that we have not yet identified – explains Steve Hoge, first author of the research – but based on what is reported in the literature, this is one of the largest
How the subsequent study was conducted
The study, conducted in the following years by researchers, delves into the biology of these wild bees, economically important but little studied, using those from the cemetery of East Lawn as a case study.
In particular, the authors applied a new method to measure the size of the population and to understand the ratio between the sexes and the moment in which males and females emerge from the ground in spring, using emergency traps, i.e. small mesh tents open at the bottom that occupy less than a square meter of ground and which trap the insects in a glass jar via a funnel.
With this approach you capture an entire community of animals emerging from the established terrain he explains Bryan Danforth
The team placed 10 traps between March 30 and May 16, 2023, collecting 3,251 individuals belonging to 16 species of bees, flies and beetles, with A. regularis as the dominant species.
The results of the work
By counting the number of bees caught in each trap, the team calculated the average bee density – the number of bees emerging from one square meter of soil – and then extrapolated this to the entire area of the cemetery, around 6,000 square metres.
Because the different traps caught different numbers of bees, the researchers calculated that the total population of A. regularis ranged from a minimum of 3 million to a maximum of 8 million specimens, with an average of 5.5 million bees.
Traps revealed that males emerge first, with activity peaking as the weather warms in April. A few days later, the females emerge.
The males come out first and wait for the females so they have the best opportunity to mate and pass on their genes
reports Hogeconfirming that A. regularis follows a pattern seen in other bee species that emerge in early spring.
The traps also allowed the team to identify and confirm brood parasitism by nomadic bees (Imbricated nomad), which emerge later than A. regularis and at a slower pace, waiting for ground bees to replenish their brood cells.
In fact, only later do they lay their eggs in the brood cells A. regularisand at that point the larva of the nomadic bee kills the larva of the miner bee that hosts it, and then feeds on the pollen and supplies present in the cell.
The project of citizen science in which anyone can participate
Danforth and his team have launched a global citizen science project on ground-nesting bees, where people around the world can report the presence of bees and aggregations they observe in their everyday lives.
These populations are huge and need protection – explains Danforth – If we don’t preserve the nesting sites and someone asphalts them, we could lose 5.5 million bees in an instant, important pollinators
The study was funded by Cornell Atkinson Center for Sustainabilityfrom the National Science Foundation and the program Federal Capacity Fundsand was published on Apidologie.
Sources: Cornell University / Apidologie
