Sick young ants send 'kill me' scent that prompts workers to remove infected pupae

Researchers report that infected ant pupae emit a scent that causes worker ants to unpack and disinfect them, which results in the pupae's death. Experiments that transferred the scent to healthy pupae produced the same unpacking response.

Scientists report that some ant pupae produce a smell that causes worker ants to unpack and disinfect them, a process known as "destructive disinfection" that ends the pupa's life. The work, led by Sylvia Cremer and collaborators and reported in Nature Communications, examines how colonies limit the spread of lethal infections. Because pupae cannot move, researchers studied how colonies prevent them from becoming sources of outbreak. The study focused on the invasive garden ant Lasius neglectus and tested whether the pupa emitted an active signal or was simply acted on by workers. Key findings: - Infected worker-destined pupae emitted a scent only when adult worker ants were present, not when left alone. - The scent prompted workers to unpack the cocoon and apply a disinfectant, a sequence that ultimately killed the pupa. - Transferring the scent to healthy pupae caused workers to unpack them, showing the odor itself triggers the behavior. - Queen-destined pupae did not signal in the same way, and producing the scent appears to use substantial pupa resources. Summary: The reported results add to understanding of social immunity by showing young ants can emit a chemical signal that leads workers to remove and disinfect infected brood, reducing the risk of wider outbreaks. Undetermined at this time.