Estimating the speed of Drosophila locomotion using an automated behavior detection and analysis system

A fundamental phenotypic trait in Drosophila melanogaster is the speed of movement. Its quantification in response to environmental and experimental factors is highly useful for behavioral and neurological studies. Quantifying this behavioral characteristic in freely moving flies is difficult, and many current systems are limited to evaluating the speed of movement of one fly at a time or rely on expensive, time-consuming methods. Here, we present a novel signal processing method of quantifying the speed of multiple flies using a system with automatic behavior detection and analysis that we previously developed to quantify general activity. By evaluating the shape of the signal wave from recordings of a live and simulated single fly, a metric for speed of movement was found. The feasibility of using this metric to estimate the speed of movement in a population of flies was then confirmed by evaluating recordings taken from populations of flies maintained at two different temperatures. The results were consistent with those reported in the literature. This method provides an automated way of measuring speed of locomotion in a fly population, which will further quantify fly behavioral responses to the environment.