Collective Behaviour of Insect Swarms under External Perturbations

在自然界中，各种各样的动物物种往往形成聚集体，往往表现出复杂和动态的时空格局。个体之间潜在的相互作用以及由此产生的潜在的集体群体行为是当前研究的主题。尽管自然蜂群受到环境流动和干扰的影响，但这些流动（无论是阵风、对流还是水流）与集体蜂群之间的相互作用是完全未知的。研究这种耦合是所提议的研究项目的中心。为此，将在实验室实验中研究一种不咬人的蠓（Chironomus riparius）与一种控制良好的瑞利-巴萨纳德对流之间的相互作用。在自然界中，蚊群往往在黄昏和黎明形成几何特征。在实验室中，这种群集可以使用外部定时光触发，使Chironomus riparius成为研究集体群集动物的最佳模型系统。使用加热板，产生对流流，并使用硬件同步相机研究与蠓群的相互作用。利用从湍流研究中了解到的立体匹配技术和拉格朗日粒子跟踪算法，可以计算出所有蠓的完整三维轨迹以及它们的速度和加速度，从而获得关于群体的完整统计信息。通过改变驱动热板的温度，从而改变对流的强度，可以定量地研究环境流动对集体成群的蠓的动态影响。利用新颖的拓扑方法，如动态持久同源性，可以详细研究环境与动物群体之间的全局结构相互作用。这些相互作用的知识对于获得对集体行为本质的更深层次的物理理解至关重要，并且在工程应用中设计有效的分布式系统，可以集体解决复杂的任务。

In nature, a wide array of animal species tends to form aggregates that often show complex and dynamic spatio-temporal patterns. The underlying interactions of the individuals and the resulting, potentially collective, swarming behaviour is subject of current research. Even though natural swarms are subject to environmental flows and disturbances, the interactions between these flows, be it wind gust, convective flows or water currents, and collective swarming are completely unknown. Investigating this coupling is the center of the proposed research project. To do this, the interaction between a non-biting midge species, Chironomus riparius, and a well-controlled convective Rayleigh-Bénard flow are to be investigated in a laboratory experiment. In nature, midge swarms tend to form at dusk and dawn over geometric features. In the laboratory, this swarming can be triggered using external timed lights, making Chironomus riparius an optimal model system to investigate collectively swarming animals. Using a heated plate, a convective flow is produced and the interactions with the midges swarms are investigate using hardware-synchronized cameras. Using stereomatching techniques and Lagrangian particles tracking algorithms know from turbulence research, full three-dimensional trajectories of all midges along with their velocities and acceleration can be computed, yielding full statistical information about the swarm. By varying the temperature of the driving heat plate and, thus, the strength of the convective flow, dynamic effects of environmental flows on collectively swarming midges can be quantitatively investigated. Using novel topological methods, such as dynamic persistent homology, global, structural interactions between the environment and animal swarms can be investigated in detail. Knowledge of these interactions is essential to obtain a deeper physical understanding about the nature of collective behaviour and potentially useful in engineering applications to design effective distributed systems that can solve complex tasks collectively.