Cross-Species Social Experience Suppresses Aggression in Drosophila

Many animals inhabit multi-species environments, competing for shared resources. Yet how cross-species experiences influence aggressive interactions remains unclear. Here, we found that prior experience with phylogenetically related Drosophila species, such as Drosophila simulans, strongly reduced inter-male aggression in Drosophila melanogaster, whereas experience with distantly related species, such as Drosophila virilis, had a weaker effect. Cross-species experience duration tunes the level of aggression suppression, whereas social isolation reverses this suppression. Mechanistically, chemosensation affected this tuning, with gustation and olfaction mediating rapid and slow effects, respectively. In addition, P1 neuronal activity signals cross-species social experiences, which suppress the approach and attack phases of aggression. Consistent with this role, P1 ablation and chronic activation eliminated and recapitulated the experience effects, respectively. Our study elucidates how cross-species social experiences shape aggressive behaviors in a species-specific manner, uncovers the roles of multiple sensory modalities in enabling time-dependent modulation effects of persistent social experiences, and implicates P1 neurons in the formation and expression of cross-species social experiences.