Mechanisms Underlying Mosquito Host-seeking Behavior

Mosquitoes have an extremely sophisticated sensory system to search for humans, and they are sensitive to the signals emitted by humans. Mosquitoes first detect CO₂ in exhaled breath. While the concentration of CO₂ in the atmosphere is 0.04%, human exhaled breath contains 1–10% of CO₂. The amount of CO₂ contained in exhaled breath varies from person to person and from the same person by activity.

Mosquitoes detect CO₂ at a distance of 10 m or more from humans and activate flight behavior. Mosquitoes then approach humans, relying on visual information and odors [1]. Eventually they detect heat and moisture and land on humans. After landing, their sense of taste detects human skin.

The behavior of mosquitoes searching for humans is complex in which multiple sensory stimuli are involved in sequence. To properly recognize and process these sensory stimuli, mosquitoes have a remarkable sensory system.

The figure shows the sensory organs of mosquitoes and the sensations they perceive [2-6]. These sensory organs have sensors (receptors) that detect their respective sensory stimuli. For example, Aedes aegypti has 129 types of olfactory receptors that perceive odors [4,7]. Mosquito olfactory receptors are also present in the labellums and legs, as well as antennae and maxillary pulps.