Supplementary material from Flight behaviour of malaria mosquitoes around odour-baited traps: capture and escape dynamics.

Host-seeking mosquitoes rely on a range of sensory cues to find and approach blood hosts, as well as to avoid host detection. By using odour blends and visual cues that attract anthropophilic mosquitoes, odour-baited traps have been developed to monitor and control human pathogen-transmitting vectors. Although long-range attraction of such traps has already been studied thoroughly, close-range response of mosquitoes to these traps has been largely ignored. Here, we studied the flight behaviour of female malaria mosquitoes (Anopheles coluzzii) in the immediate vicinity of a commercially available odour-baited trap, positioned in a hanging and standing orientation. By analysing more than 2500 three-dimensional flight tracks, we elucidated how mosquitoes reacted to the trap, and how this led to capture. The measured flight dynamics revealed two distinct stereotypical behaviours: (i) mosquitoes that approached a trap tended to simultaneously fly downward towards the ground; (ii) mosquitoes that came close to a trap changed their flight direction by rapidly accelerating upward. The combination of these behaviours led to strikingly different flight patterns and capture dynamics, resulting in contrasting short-range attractiveness and capture mechanism of the oppositely oriented traps. These new insights may help in improving odour-baited traps, and consequently their contribution in global vector control strategies.

寻宿主蚊子依赖多种感官线索定位、接近吸血宿主，同时规避被宿主察觉。研究人员借助可吸引嗜人蚊的气味混合物与视觉线索，开发出气味诱捕器（odour-baited traps），用于监测并防控传播人类病原体的媒介昆虫。尽管此类捕器的长程吸引效果已得到充分研究，但蚊子对捕器的近距离响应却长期被忽视。本研究针对市售的悬挂式与直立式两种取向的气味诱捕器，探究了雌性疟疾媒介蚊——按蚊（Anopheles coluzzii）在捕器近场的飞行行为。通过分析超过2500条三维飞行轨迹，我们阐明了蚊子对捕器的响应方式，以及该响应如何导致蚊虫被捕获。实测的飞行动力学结果揭示了两种截然不同的固有飞行行为模式：其一，接近捕器的蚊子往往同时向地面俯冲；其二，靠近捕器的蚊子会通过快速向上加速来改变飞行方向。这两种行为的组合，造就了差异显著的飞行模式与捕获动力学过程，使得不同朝向的捕器呈现出截然不同的近距离吸引力与捕获机制。本研究的新发现可为优化气味诱捕器性能、进而推动全球媒介生物防控策略的落地提供理论支撑。