Aphids are sap-feeding insects with piercing-sucking mouthparts. They are serious pests in agriculture particularly because they transmit plant viruses to most important crops worldwide. The majority of these viruses are transmitted in a non-circulative manner where viruses are retained on specific receptors located in the aphids’ outhparts. The acrostyle, an “organ” located at the tip of aphids’ maxillary stylets discovered a few years ago, bears 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 among 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 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 my PhD project will be to search for putative partners from plant (defense molecules) and from aphid saliva (effectors) that could interact temporarily with the cuticular proteins/peptides at the surface of the organ. The main approaches that will be developed and the most recent advances will be presented.