The aim of this project is to develop tomato plants which are repellent to the sweet potato whitefly Bemisia tabaci. The engineering strategy is to produce plants that are so repellent that whiteflies completely avoid the plants and can hence not transmit any virus. Such cultivars particularly when grown in combination with attractive decoy plants - are expected to have a significant effect on economic losses induced by Bemisia tabaci, and in particular the devastating viruses (mainly tomato yellow leaf curl virus, TYLCV) they transmit. European tomato production losses due to whitefly and TYLCV infestations have been estimated at 58 M per year. Assuming a reduction in crop damage of 20% in the novel varieties, with a market penetration of 20% of these varieties in about 10 years, the benefits of the project in terms of reduced crop losses amount to over 2 M per year in Europe alone. Finally, the project will lead to a reduction in pesticide residues (with an annual cost benefit of 0.5 M ), and thus contributes to increased food quality and food safety in the Dutch vegetable market.