Viticulture in Croatia has a long tradition and is characterised by at least 125 autochthonous grapevine cultivars, of witch ‘Plavac mali’ is one of the most popular. About 15% of Criatian inhabitants are directly or indirectly connected with viticulture. At the same time grapevine viruses are considered a global problem and control strategies are based on preventive measures. Nevertheless, there is a lack of knowledge about alternative hosts, the behaviour of vectors, and the impact of climate change on the entire ecosystem. Croatian autochthonous grapevines, especially in coastal areas, are highly infected with viruses, particularly those of the leafroll (grapevine leafroll-associated virus 3, GLRaV-3) and rugose wood comlexes. The Kaštela region (Central Dalmatia) is characterised by various autochthonous cultivars, but also by grapevines frequently infected with more than 10 viruses, which provides an ideal natural platform for studying various aspects of grapevine virology. The first objective of the project is to screen perennial plants as potential alternative hosts in vineyards and surrounding areas for the presence of viruses using nanopore sequencing technology. Since limited data on the impact of the viruses on Croatian autochthonous cultivars, climate change and prolonged drought periods, the second objective is to determine the impact of GLRaV-3 on ‘Plavac mali’ exposed to different levels of water stress. Various physiological parameters will be measured and analysed, including quantification of GLRaV-3. The third objective is to determine the effect of watter stress and GLRaV-3 on the behavioural patterns (activity, movement, host selection) of vine mealybug (Planococcus ficus), a common pest in vineyards and GLRaV-3 vector. the results of the project will contribute to the development of new control strategies and provide valuable data on the impact of climate change and virus infection on ‘plavac mali’ production.