Instead of nurturing their sick young, ant queens eat their infected offspring at the first sign of illness then ‘recycle’ them into producing new eggs. The queens who cannibalised their infected larvae went on to lay 55% more eggs than non-cannibalising control queens

Ant queens typically found new colonies on their own, and at the early stages are highly vulnerable to their brood being wiped out by disease. Researchers at Oxford’s Department of Biology theorised that killing off sick larvae before they became infectious could be a strategy used by queens to combat this threat.

To test this, the researchers presented founding queens of the black garden ant (Lasius niger) 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% of the infected larvae – leaving no remains – but only 6% of control larvae which had not been infected.

Lead researcher, Dr Chris Pull of Oxford’s Department of Biology, said: ‘Once the queens find a sick larva in the brood pile they get to work immediately and spend a 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 special gland at the end of their abdomen. Indeed, some of the queens were seen massaging the opening of this gland during and after cannibalism.

The queens who cannibalised their infected larvae went on to lay 55% more eggs than non-cannibalising control queens, indicating that the nutrients from the ingested offspring were recycled for reproduction.

[https://www.cell.com/current-biology/fulltext/S0960-9822(24)01001-7](https://www.cell.com/current-biology/fulltext/S0960-9822(24)01001-7)