By Matt Walker
Editor, Earth News
Male Dawson's bees commit mass murder
It is rare for any species of animal to regularly kill its own in combat.
However, male Dawson's bees, one of the world's largest bee species, are so aggressive that they kill each other en masse in a bid to mate with females.
The bees enter a frenzy of fighting, and by the time their deadly combat is over, every male bee is either killed or has perished.
The extreme behaviour, which can lead to even females being killed, is caught on film by a BBC natural history crew.
Dawson's bees (Amegilla dawsoni) are large burrowing bees that nest in the baked soil of the Australian outback.
Each year, males emerge from their burrows earlier than females.
Flight of a killer
The male bees are adapted to pursue one of two tactics for securing a mate.
Smaller, minor males patrol either flower patches where females forage, or around the periphery of the entrances to females' burrows.
However, much larger major males patrol the entrance sites for emerging females, seeking to mate with them as soon as they appear.
Up to 90% of all females are mated by major males immediately upon their emergence.
A bee brawl
But it is a far from straightforward, or even safe, act.
The scent of the female bees inflames the major males, which are built for fighting.
As a female emerges, the male bees turn on one another, competing intensely to get access to her.
Hail the loser
Bundles of male bees form, with each trying to bite another to death.
The result is mass murder, with whole generations of male bees wiping each other out to mate with females.
This frenzy of killing has been filmed by a BBC camera crew producing the landmark natural history series
Usually one male will emerge from the fighting frenzy to carry a female away to be mated.
But sometimes the males are so aggressive they they kill the females they are attempting to meet.
Another irony is that for most of the year, Dawson's bees form extremely harmonious communities.
That is because once the mating season is passed, all the males have either killed each other or since perished, leaving an all-female community to produce the next generation.
Dawson's bees belong to the genus
which includes around 250 species of large-bodied bee.
Some of its members are important agricultural pollinators in Australia and other tropical and sub-tropical areas.
One member, the blue-banded bee, uses vibration to obtain pollen, a process known as buzz pollination. The bees land on a flower and beat their wings so frequently that its shakes the pollen loose.
Another is the cutely named teddy bear bee, another solitary species whose hair wears off as it ages, leaving bald patches on its body.
The "Dawson's bee battle" is broadcast within the Insects episode of the BBC series
at 2100GMT on BBC One on Monday 16 November.