Imagine enjoying a tasty dinner alone at home—you may freely indulge without worrying about others. Now imagine sharing the same meal with friends or colleagues: depending on the social context, you may find yourself eating more carefully, adapting your food choices, restraining yourself or competing for portions, and following social norms in conversation and table manners. Social environments influence even the simplest decisions—not only in humans, but also elsewhere in the animal kingdom.
In a new study conducted at the University of Konstanz and published in Science Advances , Akhila Mudunuri, Élyse Zadigue-Dubé, and Katrin Vogt show that even tiny, seemingly solitary fruit fly larvae ( Drosophila melanogaster ) adjust their behaviour in response to their social surroundings. The team tracked larval behaviour individually or in groups on small plates using infrared cameras and markerless tracking software, measuring how far and fast the larvae moved, how often they turned, and how frequently they came into contact or close proximity with other larvae.
The results were striking: when alone, larvae moved slowly and responded strongly to environmental cues such as a sweet substrate (which they exploit as a food source) or light (which they typically avoid). In groups, however, they dispersed quickly and showed a much weaker response to these external signals. This effect was strongest when larvae reared alone were suddenly placed into a group, suggesting that early social experience shapes later behavioural responses. The team around group leader Katrin Vogt hypothesizes that spreading out may help larvae reduce competition—or even avoid cannibalism, which can occur under protein-poor conditions—while also allowing them to explore new areas more efficiently.
“Our study shows that fly larvae are clearly sensitive to the presence of other larvae in their surroundings,” explains Akhila Mudunuri. “Rather than responding only to food or light, they integrate social cues detected through multiple senses, and social context can override other environmental signals that would matter more to them if they were alone.”
Using Drosophila ’s powerful genetic toolkit—which allows specific sensory pathways to be identified and studied—the team uncovered the mechanisms underlying these behaviours. Larvae detect their peers through mechanosensory receptors that sense touch and vibrations, as well as chemosensory receptors that respond to chemical cues, pheromones, and smells. Together, these multisensory inputs allow larvae to sense one another and adjust their behaviour accordingly, in a way that—at a basic behavioural level—resembles how humans unconsciously navigate social cues in everyday life.
By providing a genetically tractable system with a fully mapped brain connectome (a map of all neuron-to-neuron connections in the brain), fruit fly larvae offer researchers a powerful model for studying how brains process social information. Understanding how these tiny nervous systems integrate social cues with other sensory inputs may help illuminate fundamental principles of decision-making across species, including humans.
Even tiny, typically “solitary” larvae display sophisticated sensitivity to social context: they adjust their movement, regulate spacing, and make context-dependent behavioural choices in the presence of peers. These findings highlight social context as a fundamental driver of behaviour, revealing that the roots of social interaction run deep across the animal kingdom.
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Caption: Fruit fly larvae adjust their behaviour in response to their social surroundings.
Copyright: Elisabeth Böker
Science Advances
Multimodal social context modulates larval behavior in Drosophila