Odor Landscapes in Turbulent Environments

TL;DR

This paper develops a Lagrangian model to predict the statistical properties of pheromone detection signals in turbulent environments, aiding understanding of moth olfactory behavior and informing technological applications.

Contribution

It introduces a novel theoretical framework for quantifying odor detection statistics in turbulent flows, validated by simulations and experiments.

Findings

Explicit probability distributions for odor detection intensity and duration.

Validation of predictions with numerical, laboratory, and field data.

Insights into the information content of odor signals for moth navigation.

Abstract

The olfactory system of male moths is exquisitely sensitive to pheromones emitted by females and transported in the environment by atmospheric turbulence. Moths respond to minute amounts of pheromones and their behavior is sensitive to the fine-scale structure of turbulent plumes where pheromone concentration is detectible. The signal of pheromone whiffs is qualitatively known to be intermittent, yet quantitative characterization of its statistical properties is lacking. This challenging fluid dynamics problem is also relevant for entomology, neurobiology and the technological design of olfactory stimulators aimed at reproducing physiological odor signals in well-controlled laboratory conditions. Here, we develop a Lagrangian approach to the transport of pheromones by turbulent flows and exploit it to predict the statistics of odor detection during olfactory searches. The theory yields explicit probability distributions for the intensity and the duration of pheromone detections, as well as their spacing in time. Predictions are favorably tested by using numerical simulations, laboratory experiments and field data for the atmospheric surface layer. The resulting signal of odor detections lends to implementation with state-of-the-art technologies and quantifies the amount and the type of information that male moths can exploit during olfactory searches.