The spectral sensitivity of mosquito photoreceptors can explain behavioral preferences for colored stimuli

Vision underlies many important behaviors such as floral foraging, seeking out vertebrate hosts, and the location of oviposition sites. Despite the medical importance of mosquito born illness and the role of vision in mosquito behavior, the spectral sensitivities of their photoreceptors have until now remained uncharacterized. Using intracellular recording methods in Aedes aegypti, we report for the first time the spectral sensitivity of mosquito photoreceptors present in the ventral compound eye. These recordings demonstrate conclusively that the majority of mosquito photoreceptors (R1-6) are green sensitive and gain UV sensitivity through a sensitizing pigment. The central photoreceptors, which are thought to play a role in color vision, show peak sensitivities in the UV, green, or show a dual peak in the blue and green. Complementing the electrophysiological data, we also investigated mosquito responses to visual stimuli through wind tunnel bioassays using visual stimuli created with a pair of novel LED spectral arrays capable of independent control of light spanning the range of 390-740 nm. These visual stimuli could also be paired with different odors allowing us to investigate the effect of odor on visual responses. In the presence of CO₂ only, the observed spectral preferences can be largely explained through an achromatic intensity response from the outer photoreceptors. However, in the presence of other odors we see evidence that the preferences are influenced by input from the central photoreceptors.