Every year, around 700,000 people die as a result of the viruses transmitted by mosquitoes. The diseases include dengue, Zika, yellow fever, and chikungunya. Thus, in order to determine the factors that attract mosquitoes to human blood, a research study has been conducted at Boston University and Rockefeller University. The study revealed alarming findings as a neuroscientist at Boston University and senior author Meg Younger stated, “This is shockingly weird. It’s not what we expected.” Moreover, the research has been published in the journal “Cell”.
It has been reported that mosquitoes contain a wired olfactory system that propels them to detect human scents. It could be in the form of CO2 or human sweat that made them automatically sense the human presence. However, it has to be noted that insects contain a specific combination of chemoreceptors in their antennas and the maxillary palp through which they can sense smells. In addition to this, researchers found that a species known as Aedes aegypti is one of its kind, that uses a different mechanism from the rest of the mosquitoes to assemble its olfactory system.
According to olfactory science, “Each neuron only has one chemoreceptor associated with it.” To demonstrate this practically, researchers used CRISPR as a gene editing tool in which they classified those mosquitoes into a single experiment whose olfactory neurons give a glow when put under the microscope and demonstrate fluorescent proteins. They give these indications on detecting different human smells that are present around them. In this way, the researchers detect the effect of different scents on the olfactory system of mosquitoes.
But the experiment took a sharp turn when researchers got to know that the species, A. aegypti, tends to link different olfactory sensory receptors to one neuron through a mechanism called “coexpression”. This unexpected revelation rocked the researchers with shock and disbelief as these results were the exact opposite of the concept of olfactory science. As Younger says, “The central dogma in olfaction is that those sensory neurons, for us in our nose, each express one type of olfactory receptor.”
The researchers further stated, “The redundancy afforded by an olfactory system… may increase the robustness of the mosquito olfactory system and explain our long-standing inability to disrupt the detection of humans by mosquitoes.” However, the main goal of the research was to develop such mosquito repellents that integrate a barrier between human scents and mosquitoes, ultimately resisting their attraction. Hence, Younger said, “As we learn about how odor is encoded in their olfactory system, we can create compounds that are more effective based on their biology.”