Memory-like dynamics in an insect's agile tracking flight

Spatial orientation involves directed behaviors, some requiring explicit positional references and others relying on moment-to-moment directional information. While both types may produce similar kinematics, they imply different neural mechanisms. A positional reference needs internal comparison to a stored condition. Can we infer such stored references (memory) from kinematics?

Agile hawkmoths, Manduca sexta feed from flowers while hovering and track movements at frequencies up to 14 Hz, maintaining a fixed lateral offset. Using robotic flowers, we investigated the dynamics of this tracking behavior. The long-time dynamics of moth offsets follow a drift-diffusion process with a preferred mean offset. The offset shows short-time superdiffusion due to inertia and long-time mean-reversion at a nonzero mean. It varies between individuals and may differ for the same individual feeding multiple times. This suggests short-term memory formation at the start of a feeding bout but may also result from resetting a velocity integrator. We compared continuous and bang-bang control as explanatory models. Thus, hawkmoth tracking dynamics suggest storage of internal position memory, likely a gated multisensory phenomenon allowing adjustments based on feeding success and corrections to drift.