The mosquito has a unique method to find its prey and pierce down the human skin for blood. It employs a combination of olfactory, visual, and thermal cues to find only those parts such as your arm, your leg, or your cheek to suck blood easily, said a study.
In a paper “Mosquitoes Use Vision to Associate Odor Plumes with Thermal Targets”, published in Science Direct, authors Floris van Breugel, Jeff Riffell, Adrienne Fairhall, and Michael H. Dickinson explain that the mosquitoes first find their prey by the smell, a fact well-established in the past research work.
“Mosquitoes use a combination of olfactory, visual, and thermal cues to locate hosts” and they are known to detect suitable hosts by the presence of a sparse CO2 plume, which they track by surging upwind and casting crosswind. Local cues such as heat and skin volatiles help them identify a landing site and the evidence suggests that thermal attraction is gated by the presence of CO2, they say.
Though the actual flight trajectories of the animals were unknown and visual cues were not studied, using the three-dimensional tracking system, researchers are able to 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 and by decoupling the olfactory, visual, and thermal cues, they see the motor reactions to these stimuli are independently controlled.
Given that humans become visible to mosquitoes at a distance of 5–15 meters, visual cues play a critical intermediate role to find targets, said researchers.
After smell, they easily see you and inch closer to you to scan the warmest body part of yours to bite, say researchers. Once, a suitably warm spot is found, the land on your skin and pierce for tasty blood. Here are the three steps the researchers have listed:
Step 1: Mosquito detects CO₂ from your breath first.
Step 2: CO₂ activates mosquito’s visual senses and the bug scans your body to decide whether it is recognizable human or animal body.
Step 3: Once the mosquito is inches closer to its target, it looks for thermal clues to find the optimal place for blood-sucking.
The study says mosquitoes can see humans or animals at a distance of between 5 and 15 meters and they detect CO₂ exhalation at distances further than 15 meters to begin tracking them. Now that these findings are in place, it will help mosquito repellant sprays, ways, and means to become far more successful in the near future, they say.