Arthropod Vector: Controller of Disease Transmission, Volume 2: Vector Saliva-Host Pathogen Interactions is built on topics initially raised at a related Keystone Symposium on Arthropod Vectors. Together with the separate, related Volume 1: Controller of Disease Transmission, this work presents a logical sequence of topic development that leads to regulatory considerations for advancing these and related concepts for developing novel control measures. The three themes of symbionts, vector immune defenses and arthropod saliva modulation of the host environment are central to the concept of determinants of vector competence that involves all aspects of vector-borne pathogen development within the arthropod that culminates in the successful transmission to the vertebrate host. These three areas are characterized at the present time by rapid achievement of significant, incremental insights, which advances our understanding for a wide variety of arthropod vector species, and this work is the first to extensively integrate these themes.