Question Corner | Can mosquitoes taste human blood?
Researchers at the Howard Hughes Medical Institute at the Rockefeller University have for the first time found that female mosquitoes have individual neurons that sense human blood’s distinctive flavour. The sense of taste is specially tuned to detect a combination of at least four different substances in blood — glucose, sodium chloride (common salt), sodium bicarbonate and adenosine triphosphate (ATP). The researchers found that female Aedes aegypti mosquitoes possess different neurons in the syringe-like stylet, which punctures the skin, to distinguish blood from nectar (Neuron, October 2020). Blood-feeding mosquitoes survive by feeding on nectar for metabolic energy, but require a blood meal to develop eggs. They found that female mosquitoes have two feeding modes that use different mouthparts and detect different flavours.
To see what’s special about the combination of these four ingredients, the researchers first tested how mosquito stylets responded to each component. Surprisingly, glucose found in both nectar and blood did not activate any neurons. But the other three ingredients — sodium chloride (common salt), sodium bicarbonate and ATP — which are found only in blood and not in nectar activated a specific group of neurons. One prominent cluster of neurons activated only when the entire blood recipe was delivered together and not individually. The findings shed light on just how specially adapted the female mosquito is to find blood.