Automated analysis of internally programmed grooming behavior in Drosophila using a k-nearest neighbors classifier

Despite being pervasive, the control of programmed grooming is poorly understood. We have addressed this gap in knowledge by developing a high-throughput platform that allows long-term detection of grooming in the fruit fly Drosophila melanogaster. Automatic classification of daily behavior shows flies spend 30% of their active time grooming. We show that a large proportion of this behavior is driven by two major internal programs. One of these programs is the circadian clock that modulates rhythms in daily grooming. The second program depends on cycle and clock and regulates the amount of time flies spend grooming. This emerging dual control model of programmed grooming in which one regulator controls the timing and another controls the duration, resembles the well-established two-process regulatory model of fly sleep. Together, our quantitative approach in Drosophila has revealed that grooming is an important internally driven behavior under the control of two regulatory programs.