Dynamics of mosquito swarms over a moving marker

Insect swarms are a model system for understanding collective behavior where the collective motion appears in disorder. To initiate and maintain a swarm in place, flying insects often use a visual external cue called a marker. In mosquitoes, understanding the swarming behavior and its relation to the marker has an additional medical relevance since swarming often precedes mating in the wild, thus constituting an important stage to intercept for controlling mosquito population. In this paper, we perform laboratory experiments to characterize the visual coupling between a swarm of mosquitoes and a marker. A laboratory microcosm with artificial lighting was built to stimulate consistent swarming in the malarial mosquito Anopheles stephensi. The experimental setup was used to conduct experiments where a mosquito swarm was filmed with a stereo camera system as a marker was moved sinusoidally with different frequencies. System identification analysis of the frequency response show that the relationship between the swarm and the marker can be described by delayed second order dynamics in a feedback loop. We find that the length of the delay correlates with the number of mosquitoes swarming on the marker indicating that time delay may be a possible parameter to capture social interactions within swarming systems. Further, model parameters obtained from fitting data provide a way to numerically compare swarming behaviors of different species with respect to marker characteristics in future experiments.