Unwelcome visitors in the night: blood-feeding pathways in mosquitoes
Everyone knows the feeling: you’re too busy sweltering in the heat of the sun to notice a silent thief stealing a drop of blood. We’re talking about mosquitoes, of course. But how can this blood-feeding process be carried out so rapidly?
That’s exactly the question that one research team decided to solve. Professors Ahn, Young-Joon and Kwon, Hyung-Wook at Seoul National University CALS were the first researchers in the world to reveal the mosquito’s extraordinary ability to find blood vessels hidden under the skin at the first attempt. Their study of rapid blood-feeding pathways in mosquitoes was published in Scientific Reports, a sister journal to the renowned journal Nature (Study Title: A novel olfactory pathway is essential for fast and efficient blood-feeding in mosquitoes).
Generally, mosquitoes are attracted to the volatile compound octenol, which stimulates them to fly closer. Here, they sense other compounds that give humans and animals their unique smell, and this triggers landing behavior. Once the mosquito lands on the skin, the blood-feeding activity begins. Previous studies had described the mosquitoes’ approach stage, but the blood-feeding mechanisms remained unknown until now.
A mosquito has a needle-like stylet; directly in front of the stylet is a sensory hair attached to an olfactory structure. Professors Ahn and Kwon discovered that this hair contains two types of olfactory receptor. The results of their experiment showed that these two types of olfactory receptor respond actively to 1-octen-3-ol and cyclohexanol—volatile odorants found in the blood. Meanwhile, these olfactory receptors do not respond to less volatile odorants, such as those constituting the smell of sweat or feet. To test this discovery, the research team inhibited the expression of these two olfactory receptors, and found that mosquitoes were no longer able to find blood vessels, and were therefore incapable of rapid blood-feeding. Furthermore, even when only one olfactory receptor was inhibited, the mosquitoes still showed a considerable impairment in their ability to find blood vessels.
By demonstrating substances that can inhibit the two olfactory receptors, the results of this study can be used to find ways to repel mosquitoes that act as vectors for meningitis and malaria. It is hoped that this will spur future research to find methods of controlling different stages of the mosquitoes’ olfactory behavior, as it relates to blood-feeding, as well to find substances that impair blood-feeding behavior.
<Professor Ahn, Young-Joon, chief researcher>
Student Reporter Lee, Sang-Wook, Kim, Dong-Jun