Odor plume tracking behavior of walking and flying insects

Many animals locate food, mates, and territories by following plumes of
attractive odors. There are clear differences in the structure of this
plume tracking behavior depending on whether an animal is flying,
swimming, walking, or crawling. These differences could arise from
different control rules used by the central nervous system during these
different modes of locomotion or one set of rules interacting with the
different environments encountered by animals suspended in flow or moving
across the ground. Flow speeds and turbulence that characterize the
environments where walking and flying insects track plumes may alter the
structure of odor plumes in an environment-specific way that results in
the same control rules generating behaviors that appear quite different.
We tested these ideas by challenging walking male cockroaches, Periplaneta
americana, and flying male moths, Manduca sexta, to track plumes of their
species’ sex-pheromones in low wind speeds characteristic of cockroach
experimental environments, higher wind speeds characteristic of moth
experimental environments, and conditions ranging from low to high
turbulence. Introducing a turbulence-generating structure into the flow
significantly improved the flying plume tracker’s ability to locate the
odor source, and changed the structure of the behavior of both flying and
walking plume trackers. Specifically, the walking and flying plume
trackers located the odor source more often in experimental conditions
characteristic of environments in which they live suggesting differing
reliance on spatial and temporal measurements of the odor plume.