Honey ant queens share a throne
Footage of ant queens working together has been captured by a BBC film crew.
As the sole reproducer in a colony, ant queens are traditionally considered lone figures.
However, in certain species unrelated queens will sometimes co-operate to kick-start a new colony.
The team filming for BBC Two series Natural World believe this is the first footage to show honeypot ant queens co-operating in the wild.
Filmmakers spent 150 days in the deserts of Arizona, US to capture the behaviour of the ants Myrmecocystus mimicus.
HONEYPOT ANT FACTS
- Honeypot ants are named for the specialist workers, called repletes, that store sugars and proteins in their swollen abdomens to feed to the colony
- The honeypots can reach the size of a cherry, despite the ants only measuring at most 2.6mm
- These ants can belong to five different groups including the Myrmecocystus which are found across North America
- Their sweet nectar makes them a target for predators from badgers to lizards
Filming the foundation of a new colony was a considerable challenge because the insects rarely ventured above ground.
The team's chance came following a mating swarm that happens only once a year.
"You can't make it happen, you just have to be there," cameraman John Brown explained.
"I knew the ants would only perform their nuptial flight after a summer storm... but the storms are infrequent, short, unpredictable, and in my first year of filming it didn't happen at all in the canyon," he said.
The honeypot ants timed their mating so that the ground was soft enough for queens to dig a nest.
After weeks of checking the weather radar through the night, John finally had the perfect opportunity to film the ants but had to do so before the sun baked them to death.
An early start paid off for the team who were able to capture in detail the greeting between two queens and their subsequent co-operation.
"I knew queens sometimes co-operated, but was amazed at the degree to which it happened... the level of communication between them was impressive and fascinating," Mr Brown told BBC Nature.
Ant expert Professor Bert Holldobler of Arizona State University said: "These queens were not related... They originated from different colonies, but nevertheless they co-operated during colony foundation.
"The main reason for that seems to be that young colonies compete with one another and raid each other, stealing the brood from other colonies. The larger the colony, the better it is at raiding neighbouring colonies."
Prof Holldobler first documented the "slave-making" behaviour of M. mimicus in 1976 and, since then, he has studied the ants' complex social behaviour.
In addition to filming the foundation of the colony, the film crew was able to film inside the nest to see what happened next.
Their cameras revealed that once the queens had raised an army of workers, a subtle but lethal "revolution" took place.
"The first queen reduction happens after about a month after the nest is founded - when the first generation of workers has hatched," explained Mr Brown.
"The process is a slow and low-key wearing down of the 'victim' queen; the workers withhold food and constantly hassle her."
Ant specialist and wrangler Ray Mendez facilitated the filming, having worked extensively with ants in the area.
End Quote Ant expert Ray Mendez
They don't necessarily sit next to each other like a bunch of chums”
Mr Mendez pointed out that, rather than valuing a single sovereign, the worker ants were simply picking off the weakest queens to manage their resources better.
After digging the nest and raising the first brood, Mr Mendez says, the weakest queens are abandoned by their colony.
"At that point, [the queen has] expended all of her energy stores," he explained.
But rather than select a single "monarch", honeypot ant colonies with sufficient space will occasionally support multiple queens.
"They don't necessarily sit next to each other like a bunch of chums," Mr Mendez said.
But with underground nests extending to depths of up to 3m, Mr Mendez has found as many as half a dozen queens in one colony.
Prof Holldobler's genetic research has also confirmed that, although it is not common, multiple queens can exist in a single colony.
"Whether they all contribute to the offspring to the same degree, or whether one queen's eggs and larvae are primarily raised to virgin queens and males and the other queens' eggs to workers, is not yet known," he said.
Natural World: Empire of the Desert Ants airs on BBC TWO at 2000 BST on Wednesday, 10 August.