Data presented in: Walking Drosophila navigate complex plumes using stochastic decisions biased by the timing of odor encounters

How insects navigate complex odor plumes, where the location and timing of
odor packets are uncertain, remains unclear. Here, we imaged complex odor
plumes simultaneously with freely-walking flies, quantifying how behavior
is shaped by encounters with individual odor packets. We found that
navigation was stochastic, and did not rely on the continuous modulation
of speed or orientation. Instead, flies turned stochastically with
stereotyped saccades, whose direction was biased upwind by the timing of
prior odor encounters, while the magnitude and rate of saccades remained
constant. Further, flies used the timing of odor encounters to modulate
the transition rates between walks and stops. In more regular
environments, flies continuously modulate speed and orientation, even
though encounters can still occur randomly due to animal motion. We find
that in less predictable environments, where encounters are random in both
space and time, walking flies instead navigate with random walks biased by
encounter timing.