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Curr Biol. 2015 Aug 17;25(16):2123-9. doi: 10.1016/j.cub.2015.06.046. Epub 2015 Jul 16.

Mosquitoes Use Vision to Associate Odor Plumes with Thermal Targets.

Author information

1
Division of Biology and Bioengineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA. Electronic address: floris@caltech.edu.
2
Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA.
3
Department of Biophysics, University of Washington, 1705 Northeast Pacific Street, HSB G424, Box 357290, Seattle, WA 98195, USA.
4
Division of Biology and Bioengineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA. Electronic address: flyman@caltech.edu.

Abstract

All moving animals, including flies, sharks, and humans, experience a dynamic sensory landscape that is a function of both their trajectory through space and the distribution of stimuli in the environment. This is particularly apparent for mosquitoes, which use a combination of olfactory, visual, and thermal cues to locate hosts. Mosquitoes are thought to detect suitable hosts by the presence of a sparse CO₂ plume, which they track by surging upwind and casting crosswind. Upon approach, local cues such as heat and skin volatiles help them identify a landing site. Recent evidence suggests that thermal attraction is gated by the presence of CO₂, although this conclusion was based experiments in which the actual flight trajectories of the animals were unknown and visual cues were not studied. Using a three-dimensional tracking system, we show that rather than gating heat sensing, the detection of CO₂ actually activates a strong attraction to visual features. This visual reflex guides the mosquitoes to potential hosts where they are close enough to detect thermal cues. By experimentally decoupling the olfactory, visual, and thermal cues, we show that the motor reactions to these stimuli are independently controlled. Given that humans become visible to mosquitoes at a distance of 5-15 m, visual cues play a critical intermediate role in host localization by coupling long-range plume tracking to behaviors that require short-range cues. Rather than direct neural coupling, the separate sensory-motor reflexes are linked as a result of the interaction between the animal's reactions and the spatial structure of the stimuli in the environment.

PMID:
26190071
PMCID:
PMC4546539
DOI:
10.1016/j.cub.2015.06.046
[Indexed for MEDLINE]
Free PMC Article

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