Biology Terminally ill ant pupae are killed by workers
Terminally ill ant pupae signal their risk of infection by changing their body odor. According to a new study, workers then disinfect them so thoroughly that they die.
02.12.2025, 17:00
SDA
In this way, the social insects prevent infectious pathogens from spreading and endangering the entire colony, as reported by a research team from Austria, Germany and France in the journal "Nature Communications".
The workers unpack the fatally diseased pupae, bite small openings in their skin and apply formic acid. This treatment immediately kills the pathogens multiplying inside the pupa, but the pupa itself does not survive the disinfection process.
For the study, the researchers infected Lasius neglectus ants with the fungal pathogen Metarhizium brunneum. After decoding the ants' chemical signal, they washed it off the diseased pupae and transferred it to healthy brood. These were also destroyed by workers. This confirmed to the researchers that it really was responsible for the destruction.
No altruism
"If a terminally ill ant hid its symptoms and eventually became highly infectious, not only would it die, but so would a large part of the colony," first author of the study Erika Dawson was quoted as saying in a press release from the Institute of Science and Technology Austria (ISTA). "What initially appears to be self-sacrifice also benefits the animal that sends the signal, as it protects its relatives." These ants carry the genes of the self-sacrificing sick ants into the next generation.
However, the ant pupae do not signal every cold. "Thanks to their strong immune system, queen pupae can contain infections themselves and do not send out a warning signal," says Dawson. The worker pupae also only alert the colony when the fight against the infection in their own bodies has been lost. This prevents unnecessary sacrifice of animals that will recover on their own.
