History dependence in insect flight decisions during odor tracking

Area of Science:

• Behavioral Ecology
• Neuroethology
• Animal Navigation

Background:

• Natural decision-making involves complex sequences responding to variable stimuli.
• Animals like fruit flies (Drosophila melanogaster) and mosquitoes (Aedes aegypti) track odor plumes for resources, but turbulence creates intermittent signals.

Purpose of the Study:

• To investigate how flying insects use sparse odor encounters to generate goal-oriented behaviors.
• To determine if odor-triggered turns depend on specific encounter features and historical context.

Main Methods:

• Analyzing flight trajectories of fruit flies and mosquitoes in controlled odor plumes.
• Simulating trajectories from normative tracking strategies (reactive, centerline learning, infotaxis) for theoretical comparison.

Main Results:

• Odor-triggered turns were modulated by encounter concentration (higher concentration = stronger turn) and encounter sequence (later encounters = weaker turns).
• A purely reactive strategy or centerline learning strategy did not explain the observed history dependence.
• Infotaxis (maximizing information gain) showed history dependence aligned with data, but with greater magnitude.

Conclusions:

• Plume tracking is primarily a reactive odor response but includes history-dependent modulations.
• Short-term memory processes influencing decision sequences may be crucial for natural plume tracking in insects.