Background and Aims: In the context of life-history performance, better fitness is evident in insect populations when they correlate positively with the nutritional quality of their host-plants. We determined the chemical differences in the leaves of five cultivars of Vitis vinifera in relation to feeding by Epiphyas postvittana and evaluated larval and adult reproductive performance on the selected cultivars. Methods and Results: We determined total nitrogen, carbohydrates, phenolic substances and potassium, iron, sodium and zinc in V. vinifera cv. Chardonnay, Sauvignon Blanc, Merlot, Semillon and Marsanne. The life-history performance of E. postvittana was evaluated by raising it from eggs on leaves of the cultivars. Nitrogen content of Chardonnay was significantly greater than that of the other cultivars. Different cultivars of V. vinifera influenced growth parameters such as larval-developmental time and female-pupal mass. Reproductive-performance, measured as fecundity and fertility rates and adult-male longevity, varied when reared on leaves of the cultivars of V. vinifera. Conclusion: Leaves of Chardonnay have the highest nitrogen concentration and enhanced larval performance of E. postvittana. A fitness-index study shows that female-reproductive performance was significantly enhanced when reared on Chardonnay, whereas it declined when reared on Marsanne. Significance of the Study: Differences among cultivars of V. vinifera in terms of leaf chemistry are critical for larval performance and adult-reproductive potential. The poor response of E. postvittana on Marsanne could be useful in integrated pest management via push—pull strategy by planting Marsanne either near or among the susceptible cultivars of V. vinifera.