C. elegans Aggregation & Social Feeding

Aggregation (social feeding) assays score whether C. elegans feeds in dispersed solitude or clumps together into groups at the border of a bacterial lawn. The behavior maps to natural genetic variation: de Bono and Bargmann (1998) showed that a single amino-acid difference in the neuropeptide-Y-receptor homolog NPR-1 distinguishes social strains (which aggregate and border) from solitary strains (which feed dispersed), making aggregation a textbook example of a behavioral polymorphism with a defined molecular basis.

Aggregation is driven substantially by ambient-gas sensing — social strains avoid higher oxygen and accumulate where worm density lowers local O2 — and is modulated by a network of sensory neurons and neuropeptide signaling. This links a visible group behavior to oxygen and carbon-dioxide chemosensation and to neuromodulatory state, so aggregation read-outs report simultaneously on social tendency, gas sensing and the underlying circuit.

ConductVision quantifies aggregation from overhead video by segmenting the population into clusters versus dispersed animals, scoring clumping fraction, border occupancy, group size and aggregate count over time, plus nearest-neighbor spacing and cluster persistence. Time-resolved tracking captures how quickly groups form and how stable they are, replacing subjective visual scoring of "social" versus "solitary" plates.

The assay is used in behavioral-genetics research (npr-1 and modifier screens), in oxygen/carbon-dioxide chemosensation studies, and in work on neuromodulation of collective behavior. Oxygen level, lawn thickness, worm density and humidity strongly shape aggregation, so these must be controlled; because the read-out is a whole-population property, many animals are imaged together, giving naturally high throughput.