Aphids are sap-feeding insects with piercing-sucking mouth parts. They are serious pests in agriculture particularly because they transmit many plant viruses to most important crops worldwide. The majority of viruses are transmitted in a non-circulative manner where the virus is retained on specific, yet unknown, receptors located in the aphids’ stylets. A thorough characterization of the ultrastructure of the stylets lead to the discovery of the acrostyle, “organ” located at the tip of aphids’ maxillary stylets, that harbors the receptors of Cauliflower mosaic virus and likely those for numerous agronomically important non-circulatively transmitted viruses. Apart from transmitting plant pathogens, the acrostyle, which is conserved a cross many aphid species, has likely a role for the insect itself. At the confluence of the salivary and food canals, in contact with cell content, phloem sap and aphid saliva, the acrostyle may have a specific role(s) during the aphid feeding process, leading to plant/insect compatible interactions. In attempts to define the physiological functions of the acrostyle, the main goal of this project will be to search for putative partners that could interact with the cuticular proteins/peptides at the surface of the organ and to characterize deeply the interactions. Several approaches will be developed among which classical biochemical interaction assays, the screen of yeast--‐two--‐hybrid libraries. The role of the acrostyle will also be performed through RNAi technology.