Ant queens eat their infected offspring at the first sign of illness, then benefit from the nutrients when producing new eggs, a study led by the University of Oxford has found.

Researchers at the university's Department of Biology believe this is a survival strategy used by ant queens to protect their colonies from disease.

It has only been observed in queens, and never among mature worker ants.

The research focused on the black garden ant, which typically founds new colonies alone and is highly vulnerable to disease at this stage.

The researchers presented founding queens with larvae that had been infected with a fungal pathogen, Metarhizium, for 24 hours.

At this point, the infection was lethal but not yet transmissible.

The queens cannibalised 92 per cent of the infected larvae, leaving no remains, but only six per cent of control larvae which had not been infected.

Lead researcher Dr Chris Pull, from Oxford's Department of Biology, said: "Once the queens find a sick larva in the brood pile, they get to work immediately and spend several hours chewing them up until they're all consumed."

Despite the potential risk of infection, all queens survived after eating the infected larvae.

The researchers suggest the queens may protect themselves by swallowing an acidic, antimicrobial venom which they produce from a gland at the end of their abdomen.

Some of the queens were seen massaging the opening of this gland during and after cannibalism.

Those who cannibalised their infected larvae lay 55 per cent more eggs than those that did not, suggesting, researchers said, the nutrients from the ingested offspring were recycled for reproduction.

Co-author Flynn Bizzell, also from Oxford's Department of Biology, said: "Ant queens start their colonies alone and essentially starve themselves to raise their first workers.

"The queens who produce the most workers have the best chances of survival, so being able to eat and recycle infected larvae back into brood production means valuable resources are not wasted."

When the queens were presented with diseased larvae which had progressed to the infectious stage, they did not attempt to eat them.

Instead, they sprayed the infectious larvae with their antimicrobial venom, which may have been an attempt to control the infection.

Around 80 per cent of the queens still contracted the disease and subsequently died.

Dr Pull added: "Our results provide compelling evidence that cannibalism solves the problem of disease containment and corpse disposal in the confined space of founding queens' underground bunker, whilst also ensuring valuable nutrients are not wasted - and that this improves their chances of successful colony foundation."