Eli5: How do mosquitoes perceive CO2 ?


As far as I know, mosquitoes are able to perceive the carbon dioxide released by human beings, and the discrepancies between people regarding how often they are bitten is due to variable CO2 release, making for instance pregnant women more vulnerable.

Now I wonder how do those bugs perceive the CO2. Do they have specialized organs ? Do they “smell” it ?

In: Biology

The only thing I know about mosquitoes with respect to CO2 is that their larvae are very vulnerable to it… my preferred method for killing them in my rain barrels was to drop in a chunk of dry ice and wait to scoop up all the dead.

As for your question, I’m not sure that’s their primary way of detecting prey – your appendages aren’t releasing CO2, yet they are most often the target. They seem to be attracted to heat and light. Possibly moisture and maybe pheromones. I’m interested to read an entomologist’s take.

A number of compounds secreted by humans have been shown to be mosquito attractants, including lactic acid from human skin and exhaled breath, 1-octen-3-ol from human sweat and breath, and carbon dioxide—human breath is ∼4% CO2, with traces expired from skin. In fact, carbon dioxide appears to be one of the most potent mosquito stimulants.

Mosquitoes have two sets of noses: the antennae and maxillary palp in their head. These “smell” organs are covered by specialized sensory hairs called sensilla that usually house two to three olfactory neurons. Odorants activate olfactory receptors expressed on the dendrites of olfactory neurons to transmit signals into the brain. The smell activity of these neurons has been directly measured by inserting a recording electrode into the sensilla.