Mosquitoes escape looming threats by actively flying with the bow-wave induced by the attacker

Abstract

To detect and escape from a looming threat, night-flying insects must rely on other senses than vision alone. Nocturnal mosquitoes have been described to escape looming objects in the dark, but how they achieve this is still unknown. Here, we show how night-active female malaria mosquitoes escape from a rapidly looming object that simulates the defensive action of a blood-host. By combining videography-based automatic tracking with numerical simulations of the attacker-induced airflow, we first show that night-flying mosquitoes use airflow-sensing to detect the danger and trigger their escape. Secondly, by combining these data with mechanistic movement modelling, we unravelled how mosquitoes control their escape manoeuvres: they actively steer away from the danger, and passively travel with the bow-wave produced by the attacker. Our results demonstrate that night-flying mosquitoes escaping from a looming object use the object-induced airflow both to detect the danger, and as fluid medium to move with for avoiding collision. This shows that the escape strategy of flying insects is more complex than previous visually-induces escape flight studies suggest. As mosquitoes are average-sized insects, a combined airflow-induced and visual-induced escape strategy is expected to be common amongst millions of flying insect species. Also, our research helps explain the high escape performance of mosquitoes from counterflow-based odour-baited mosquito traps. It can therefore provide new insights for the development of novel trapping techniques for integrative vector management.