Transcriptional predictors of rescue behaviour in ants

Some social animals can recognize and respond to the distress of group members. While well documented in mammals, such behaviour has also independently evolved in ants. To uncover the molecular basis of this social trait, we compared gene expression in the central and peripheral nervous system of Cataglyphis nigra workers differing in rescue propensity. RNA-seq of mushroom bodies, optic lobes, central brain and antennae revealed nine genes upregulated across all tissues of rescuers, including those encoding cytochrome P450-9e2 (CYP9E2) and arginase, and immune-related genes such as the defensin (DEFA) and serine protease snake (snk) genes. The mushroom bodies showed the strongest signal, including genes involved in juvenile hormone signalling, polyamine synthesis and immune function. These results suggest that the immune pathways and polyamine metabolism modulate social responsiveness or alarm-cue detection in ants. In contrast, morphological and physiological traits did not differ between rescuers and non-rescuers, indicating that rescue behaviour propensity is governed by the activity of the nervous system.