The molecular and cellular basis of short-range host cue sensing in mosquito vectors

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PROJECT SUMMARY/ABSTRACT Mosquito disease transmission relies on the insect’s ability to feed on human hosts, a behavior driven by host- associated sensory cues. Temperature and humidity are key short-range cues that promote the final stages of host approach and biting, but little is known about the molecular and cellular basis of mosquito responses to these cues, or whether these mechanisms are conserved among evolutionarily distant mosquitoes. We propose to address these knowledge gaps by: 1) Probing the molecular basis and evolutionary conservation of heat-seeking between the malaria vector Anopheles gambiae (An. gambiae) and the dengue vector Aedes aegypti (Ae. aegypti). 2) Investigating the (as yet unknown) molecular and cellular basis of mosquito humidity sensation in An. gambiae. We propose to achieve these goals in three aims: Aim 1) Probe the evolutionary conservation of heat seeking mechanisms. Mosquito blood-feeding is thought to have a common evolutionary origin, but whether the mechanisms that control heat-seeking are conserved across mosquitoes is an open question. We will test this conservation by comparing the roles of key receptors implicated in heat-seeking in multiple mosquito species in order to reveal whether and in what ways heat-seeking mechanisms are shared across vector mosquitoes. Aim 2) Determine the sensory specificities of candidate humidity receptor-expressing neurons in An. gambiae. Despite its importance for host seeking, mosquito humidity sensing is largely unexplored. We will test the hypothesis that mosquito humidity sensors rely on relatives of receptors important for sensing humidity in Drosophila. We will examine the stimulus sensitivities of the sensory neurons expressing these receptors and test the role(s) of these receptors in detecting sensory stimuli. Aim 3) Establish the behavioral roles of candidate hygroin An. gambiae. We will test how our candidate receptors for humidity and temperature contribute to the mosquito’s behavioral responses to humidity and temperature, as well as host seeking and blood feeding. We will also compare how host-seeking roles relate to homeostatic roles in helping modulate body temperature and hydration state. This work will identify molecular receptors and sensory neurons that detect temperature and humidity in vector mosquitoes and establish their roles in mosquito host seeking and blood feeding. As these behaviors supports disease transmission, these basic science findings have potential relevance for vector control efforts.