Sensory Discrimination of Blood and Floral Nectar by Aedes aegypti Mosquitoes

Blood-feeding mosquitoes survive by feeding on nectar for metabolic energy but require a blood meal to develop eggs. Aedes aegypti females must accurately discriminate blood and nectar because each meal promotes mutually exclusive feeding programs with distinct sensory appendages, meal sizes, digestive tract targets, and metabolic fates. We investigated the syringe-like blood-feeding appendage, the stylet, and discovered that sexually dimorphic stylet neurons taste blood. Using pan-neuronal calcium imaging, we found that blood is detected by four functionally distinct stylet neuron classes, each tuned to specific blood components associated with diverse taste qualities. Stylet neurons are insensitive to nectar-specific sugars and respond to glucose only in the presence of additional blood components. The distinction between blood and nectar is therefore encoded in specialized neurons at the very first level of sensory detection in mosquitoes. This innate ability to recognize blood is the basis of vector-borne disease transmission to millions of people worldwide. •Neurons in the syringe-like stylet are the first to detect blood as mosquitoes bite•The taste of blood is integrated across taste qualities and stylet neuron subsets•Subsets are tuned to distinct blood components and insensitive to floral sugars•Polymodal taste quality integration assigns a blood-specific context to glucose Jové et al. characterize specialized blood-feeding sensory neurons in female Aedes aegypti mosquitoes and demonstrate that they encode the distinction between blood and floral nectar. Polymodal integrator neurons respond to glucose only in the presence of additional blood components, allowing mosquitoes to discriminate these two appetizing food sources.