Modulation of mosquitoes' responses to visual threats

Despite the associated risks, female mosquitoes must feed on mobile and defensive hosts to obtain the proteins and nutrients required to produce progeny. During the process of searching and drinking our blood, these female mosquitoes are exposed to the risk of being detected and either hurt or killed by our swats. Consequently, their ability to detect and avoid these threats is directly related to their fitness and reproductive success. While visually guided escape responses have been extensively analyzed in classical model species such as Drosophila melanogaster, how mosquitoes detect and respond to visual threats has only started to be unraveled. In this work, we combined behavioral, immunohistochemical and electrophysiological methods to determine how Aedes aegypti females respond to visual threats across different ecological contexts. Using a 3D virtual reality arena to present looming stimuli designed to mimic a swatting hand, we observed that visual threats trigger oriented escape responses in both flying and landed mosquitoes, and can prevent females from blood-feeding on an artificial feeder. Investigations into the neural basis of these responses revealed the presence of large descending neurons comparable to the Giant Fiber Neuron system identified in fruit flies. These results will be discussed in the context of mosquitoes’ adaptations to feeding on live and defensive hosts.