Plant Viruses as Master Manipulators: Exploiting Host Plants and Insect Vectors for Enhanced Transmission.

Plant viruses are evolutionarily endowed with traits that enhance their survival and dissemination attributes both in host plants and insect vectors. This review highlights current understanding of these multifaceted interactions, positioning plant viruses as master regulators of the intricate tripartite interactions. Direct viral effects on vector physiology and behaviour, highlighting evidence that viral infection may contribute to changes in olfactory systems, epigenetic modifications, involvement of salivary effectors, and horizontal gene transfer events that may vary vector competence, were summarised. The indirect mechanisms mediated through virus-induced alterations in host plant responses, including changes in volatile emissions, the development of visually and chemically attractive symptoms, and modulation of host immune defences that may influence vector attraction and feeding behaviour, were discussed. These viral infections have profound ecological and agricultural consequences, reflecting the fine balance these pathogens maintain between preserving host viability and maximising transmission. In intensively managed agro-ecosystems, environmental and biological conditions can strengthen these interactions, potentially promoting epidemic spread and altering vector behaviour. Deciphering these evolutionary strategies deepens our understanding of the dynamics governing pathogen-host-vector systems and opens new possibilities for designing targeted, sustainable interventions to disrupt viral transmission in crops.