One of the overlooked points in mosquito blood feeding research is a final step before blood feeding. We provide the anatomical and chemosensory evidence that a piercing structure of the mouthpart of the mosquitoes is an essential apparatus for the penultimate stage in blood feeding in mosquitoes. Indeed, the stylet possesses a number of sensory hairs located at the tip of the stylet. These hairs house olfactory receptor neurons that express two conventional olfactory receptors of Aedes aegypti (AaOrs), AaOr8 and AaOr49, together with the odorant co-receptor (AaOrco). In vivo calcium imaging using transfected cell lines demonstrated that AaOr8 and AaOr49 were activated by volatile compounds present in blood. Taken together, we identified olfactory receptor neurons in the stylet involved in mosquito blood feeding behaviors, which in turn indicates that olfactory perception in the stylet is necessary and sufficient for mosquitoes to find host blood in order to rapidly acquire blood meals from a host animal.

• Je Won Jung(Biomodulation Major, Department of Agricultural Biotechnology Research Institute of Agriculture and Life Sciences, College of Agriculture & Life Sciences, Seoul National University)
• Sae woom Choi(College of Life Sciences, Incheon National University)
• Hyung Wook Kwon(College of Life Sciences, Incheon National University)