Social context modulates cannibalistic attraction in Drosophila larvae

Abstract Animals often face conflicting decisions to ensure survival. Under food limitation, cannibalism can provide a nutritional advantage despite substantial costs. In Drosophila melanogaster larvae, feeding is essential for successful metamorphosis, making food source decisions critical. We find that dead conspecifics act as attractive cues, but this attraction is weak for live larval groups. It is enhanced when dead larvae are injured or homogenized, or after repeated exposure. Larvae are also more attracted to dead individuals from other Drosophila or insect species. Testing live larvae individually revealed the strongest attraction, indicating that social context suppresses feeding-related attraction. Attraction to dead conspecifics depends on multiple chemosensory and mechanosensory modalities, highlighting the complex integration of social and nutritional cues in larval decision-making. Our results indicate that fly larvae flexibly balance attraction and avoidance based on social context to optimize resource use under ecological constraints. Short summary Drosophila melanogaster larvae flexibly balance attraction and social avoidance when encountering dead conspecifics. Attraction depends on carcass condition, prior experience, and social context, and is mediated by chemosensory, gustatory, and mechanosensory pathways. These findings reveal how larvae integrate multimodal social and nutritional cues to guide context-dependent feeding decisions.