Olfactory modulation of color vision and behavior in mosquitoes - PROJECT SUMMARY This application aims to build on our recent discoveries of olfactory “gating” of visual attraction in Aedes aegypti mosquitoes and determine the role of color vision in host and nectar selection. Without vision, mosquitoes cannot track odors, locate hosts, or find mates. Vision is a critical sensory modality involved in long-range olfactory search behaviors and near-host behaviors involved in landing and biting. Despite this potential importance, little is known about vision in anthropophilic mosquitoes and the neural bases of these behaviors. Mosquitoes can see a host from 2-15 m, and our recent findings show that odor “turns on” their visual attraction to hosts, thereby playing a critical role by linking long-distance odor tracking with short-range behaviors near the host. Our work also demonstrated that mosquitoes are sensitive to wavelengths reflected from human skin. However, we lack an understanding of how odor sensitizes the visual system, and the visual preferences of diverse anthropophilic mosquitoes. We have developed new tools to examine olfactory-visual integration, including new Aedes GCaMP6s mosquito lines, the generation of opsin knockout lines, and biogenic amine receptor mutants. This proposal builds on our preliminary findings that demonstrate the importance of color vision and neuromodulators in olfactory-visual integration in mosquitoes. Using semi-field and behavioral assays, calcium imaging in tethered flying mosquitoes, and molecular-genetic approaches, we propose to study the color preferences of mosquitoes and how odor modulates visual neurons. Aim 1 will allow us to characterize the colors (wavelengths) that attract different anthropophilic mosquito species and identify the odors that turn on visual search behaviors. In Aim 2, using Aedes aegypti, we will determine the neural mechanisms by which odors turn on visual search behaviors, and identify the rhodopsins that detect important wavelengths. Our preliminary results indicate that octopamine is critical for olfactory-visual integration. We will generate cell- specific knockout of the octopamine receptor to determine how olfactory-visual behaviors are compromised. In parallel, we will mutate specific long- and short-wavelength rhodopsins to suppress attraction to colors indicating hosts or nectar sources. We will also use new GCaMP6s lines to record from visual neurons in the mosquito brain and characterize how odor modulates those neurons. Aim 3 will test the wavelengths and visual features (motion, object size) that mosquitoes find attractive, and test them in new trap designs in semi-field trials. While there has been extensive work on olfaction in mosquitoes, our work emphasizes that color vision also plays a key role. Olfactory-visual integration is vital in diverse insect vectors, including tsetse flies and kissing bugs. We suggest that our proposed experiments provide a basic framework for understanding how these cues influence haematophagous insects. Furthermore, results from this work will provide information on attractive visual lures, and motivate the identification of molecular targets to cripple visual-olfactory behaviors.