Mosquitoes sense infrared from body heat to help track humans down, reveals study

Scientists led by researchers at UC Santa Barbara have discovered that one mosquito species – Aedes aegypti -overwhelmingly navigated toward infrared source while host seeking.
One species, Aedes aegypti, spreads the viruses that cause millions of cases of dengue, yellow fever and Zika each year.
According to a study published in Nature, scientists have discovered there is no one single cue that these insects rely on. Instead, they integrate information from many different senses across various distances.
“The mosquito we study, Aedes aegypti, is exceptionally skilled at finding human hosts,” said co-lead author Nicolas DeBeaubien, a former graduate student and postdoctoral researcher at UCSB in Professor Craig Montell’s laboratory. “This work sheds new light on how they achieve this.”
It is well established that mosquitoes like Aedes aegypti use multiple cues to home in on hosts from a distance. “These include CO2 from our exhaled breath, odors, vision, [convection] heat from our skin, and humidity from our bodies,” explained co-lead author Avinash Chandel, a current postdoc at UCSB in Montell’s group. “However, each of these cues have limitations.” The insects have poor vision, and a strong wind or rapid movement of the human host can throw off their tracking of the chemical senses. So the authors wondered if mosquitoes could detect a more reliable directional cue, like infrared radiation.
Within about 10 cm, these insects can detect the heat rising from our skin. And they can directly sense the temperature of our skin once they land. These two senses correspond to two of the three kinds of heat transfer: convection, heat carried away by a medium like air, and conduction, heat via direct touch.