A Neuromechanical Model of Larval Chemotaxis

Larval Drosophila move up attractive chemical gradients, and down aversive ones. Although their movement is often characterised as a series of runs and directed turns, it can also be modelled as a continuous modulation of turning extent by the detected change in stimulus intensity as the animal moves through the gradient. We show that a neuromechanical model of peristaltic crawling and spontaneous bending in the larva can be adapted to produce taxis behaviour by the simple addition of a local segmental reflex to modulate transverse viscosity (or ‘bendiness’) proportionally to the intensity change detected in the head. Altering the gain produces weaker or stronger, negative or positive taxis, with behavioural statistics that qualitatively match the larva.