Who would have guessed that our own backyards might be a battlefield for bees?
And that these deadly skirmishes involve aerial battles lasting days, with hundreds of fatalities from both attacking and defending sides, ousting the helpless from the hive and culminating in the eventual overthrow of the resident queen and installing their own in her place.
A cluster of dead native bees on the ground in a Brisbane backyard was enough to convince a group of scientists to dig deeper into this unusual behaviour of the Australian native bee species, Tetragonula carbonaria.
Their further investigations led to a surprising discovery, that the study colony was not only being attacked by its own species but also by a closely related species, T. hockingsi.
A fight to the death
Prior to this study, only the one species of bee, T. carbonaria was known to engage in battles between neighbouring colonies involving mass fatalities but this study provides the first evidence of fatal fighting between different species.
Fighting to the death or ‘fatal fighting’ is relatively rare in nature. Evolutionary biologists propose that this is because species have evolved different ways to assess strength and fighting ability that doesn’t involve the loss of the individual.
In species where fighting does escalate to death, scientific theory predicts the risk of death is outweighed by the benefits being obtained, such as fighting for scarce food resources, mates or nest sites.
Fatal fighting has been well studied in ants with beneficial outcomes including slave-making, raiding of nest supplies and gaining access to new food sites.
In the case of the T. carbonaria, the researchers hypothesised that the fighting swarms were most likely attempts at taking over neighbouring hives.
To test their hypothesis, they made regular observations on the ‘study’ hive in the backyard and collected the dead bees after fights for analysis. Using modern molecular techniques they were able to track which group of bees were attacking and which were defending. It was this analysis that lead to the surprising discovery that the attacking bees were in fact a separate species.
Following a succession of attacks by the same T. hockingsi colony over a four-month period, the defending T. carbonaria colony was defeated and the hive usurped, with the winning colony installing a new queen.
To ensure that what had occurred at the study hive was not a one-off event, our researchers monitored the colonies of over 260 commercial T. carbonaria hives over a five-year period, recording any changes in species through changes in hive architecture (see note).
They found evidence of 46 interspecies hive changes (via the change in hive architecture) during the five year period, which were most likely to be usurpation events.
There is still much to be learnt about these small creatures, such as what instigates the attacks how and when the invading queen enters the nest, and whether the young in the usurped hive are spared and reared as slaves, or killed outright.
In the case of our native bees, it is thought that the capture of a fully provisioned nest (including ‘propolis’, pollen and honey stores) is a sufficiently large benefit that it outweighs the loss of so many lives.
Let’s ‘bee’ clear, we still need further research
The researchers are quick to point out that this is an excellent example of how little we actually know about small stingless bees, which can be an excellent and resilient alternative pollinators to declining honey bee populations.
NOTE: T. carbonaria has a brood chamber, in which cells are even and connected by their walls to adjacent cells at the same height, whereas T. hockingsi brood chamber takes on a less organised appearance, being an irregular lattice comprised of clumps of around ten cells connected by vertical pillars.
Find out more about our work leading the Global Initiative for Honey bee Health and the research we are conducting with bees.
21st January 2020 at 4:32 pm
I have a Tetragonula carbonaria hive on the front porch of my house in Willoughby – a suburb of Sydney. My hive is under attack from a rival T. carbonaria hive again today the 21-Jan-2020.
This morning at 9am there was a fighting swarm about 3m in front of the hive.
At 12 the swarm had gone and the bees had returned to foraging.
Now at 16:30 there is another fighting swarm.
Our hive has been attacked each day for the last 4 days.
I first noticed our hive being attacked on 3-Jan-2020.
1st April 2018 at 7:10 am
My Tetragonula Carbonaria hive was under attack by a rival hive (also T. Carbonaria) in Lismore N.S.W. On the first day I let it go and thousands of bees died. So on the second day I decided that because my hive was made up of a log (being the original hive) and a home made hive (looking like a mini house joined up by a pipe) that I could remove the log and take it to a friends place in the hope to save more bee’s dying. So I did it and only an hour later the invading hive have moved into the mini house and my log full of bees is safely in a friends backyard and hooked up to another hive in the hope they will move in. My only concern is that I took the log away that is full of honey and pollen and the the mini house that was in the early stages of being filled out with honey by the original bee’s will not be enough to keep the invaders happy and will disappear… time will tell.
29th September 2017 at 8:43 am
I have six box,s in close proximity and just last Saturday made a split of one box.I completely renewed both sections [Old boxes being past use by date]Made good drainage holes . Placed brood just off the bottom using gutter guard as a spacer. Made ant proofing using a square of old ply Screwing two 40mmm screws right through the ply at one end and two screws 35mm at the other end. The points of the screws stopped the box,s from sliding. Then coating the exposed screw threads with grease.Today
I have a battle royal going across four hive,s I am somewhat at a loss. I did intend this weekend to take a peek through the clear panel under the lid but will wait and see if the fight recedes a bit. Any comments? I plan to go to the Chapel Hill meeting on Sunday all being well
28th January 2017 at 10:18 am
I nave a battle raging in my back yard at this very moment. This is the fourth day. This morning I swept up two large shovelfuls of dead bees. Must be thousands of them!! It’s still going on in Mareeba North Qld. 28 Jan 2017.