The olfactory gating of visual preferences to human skin and visible spectra in mosquitoes

Diego Alonso San Alberto,Andrew D Straw,Craig Montell,Jeffrey A Riffell,Claire Rusch,Yinpeng Zhan

doi:10.1038/s41467-022-28195-x

Abstract

Mosquitoes track odors, locate hosts, and find mates visually. The color of a food resource, such as a flower or warm-blooded host, can be dominated by long wavelengths of the visible light spectrum (green to red for humans) and is likely important for object recognition and localization. However, little is known about the hues that attract mosquitoes or how odor affects mosquito visual search behaviors. We use a real-time 3D tracking system and wind tunnel that allows careful control of the olfactory and visual environment to quantify the behavior of more than 1.3 million mosquito trajectories. We find that CO2 induces a strong attraction to specific spectral bands, including those that humans perceive as cyan, orange, and red. Sensitivity to orange and red correlates with mosquitoes’ strong attraction to the color spectrum of human skin, which is dominated by these wavelengths. The attraction is eliminated by filtering the orange and red bands from the skin color spectrum and by introducing mutations targeting specific long-wavelength opsins or CO2 detection. Collectively, our results show that odor is critical for mosquitoes’ wavelength preferences and that the mosquito visual system is a promising target for inhibiting their attraction to human hosts.

Highlights

Mosquitoes track odors, locate hosts, and find mates visually
We show that when encountering odor, mosquitoes become attracted to hues that are dominant in human skin
A checkerboard pattern was projected on the bottom of the wind tunnel, and a low-contrast gray horizon was projected on each side of the tunnel to provide optic flow (Fig. 1c)

Summary

Introduction

Mosquitoes track odors, locate hosts, and find mates visually. The color of a food resource, such as a flower or warm-blooded host, can be dominated by long wavelengths of the visible light spectrum (green to red for humans) and is likely important for object recognition and localization. The behavioral preference of insects for certain bands in the visible light spectrum plays a profound role in structuring ecological communities by mediating processes such as plant-insect/predator-prey interactions and disease transmission[1,2,3] For biting insects, such as mosquitoes, tsetse flies, and kissing bugs, vision plays an essential role in various behaviors, including flight control, object tracking for host- or nectar-finding, and locating oviposition sites[4]. Because many mosquito species are attracted to dark visual objects, responses to long wavelengths (red to human observers) may represent achromatic responses from visual channels that are sensitive to medium-wavelengths and are perceived as dark gray or black when presented against a light-colored background These prior studies did not characterize the actual flight trajectories of the mosquitoes, nor control for the change in behavioral state associated with the smell of a host. Little is known about opsin tuning, they are orthologs of medium-wavelength sensitive opsins (green), and previous electroretinogram (ERG)

Methods

Results

Conclusion