No matter what we do, those pesky mosquitos always seem to find us. We've lathered up in bug-repellent spray and covered ourselves head-to-toe in clothing, but we'll still return home to find those darn itchy red lumps. How are they such effective hunters, and how do they always know where we are and where we're weak? A recent study conducted by Boston University and Rockefeller University researchers has uncovered some answers to these questions. And they are weirder than we ever imagined...
According to the study, the reason Mosquitos are so accurate with their attacks is because of their very unique olfactory system, which is wired with an inbuilt human scent detector. With their special chemoreceptors in their antennae and the maxillary palp, they can expertly pick up on the CO2 or sweat being released by their human prey and effortlessly identify their whereabouts.
This new study investigated the strength of these sensors, even when the specific human chemoreceptors were disabled. To their surprise, one mosquito species, Aedes aegypti, stood out compared to all other animals in the way it organizes its olfactory system. Using a gene-editing tool, scientists could manipulate mosquito olfactory neurons to glow under a microscope when near certain smells. This helped them see how the system reacts to various scents. Going against existing scientific principles, A. aegypti showed to connect several olfactory sensory receptors to one neuron, known as coexpression. In most other species, each sensory neuron will express one type of olfactory receptor, so with at least twice as many receptors as glomeruli, this is a "striking mismatch" and "shockingly weird," according to researchers. These redundant mechanisms help to explain why we have so far been unable to disrupt mosquito to human detection.
What can be done with this information? The research team's goal is to use the data to create new and improved repellent formulas. Now it is clear how they pick up on human scents; we understand the need for products that conceal the human smell and distract the mosquitos elsewhere. Mosquito-carried diseases such as dengue, Zika, yellow fever, and chikungunya kill around 700,000 people each year, emphasizing the urgency for this research. Read the full study for all the details.