The impact of elevated CO2 levels, air temperature and humidity on the interaction between plant, sap-sucking insects, and their antagonists and symbionts (multi-trophic interaction) has not been studied in detail. Whiteflies are an important sap-sucking insect pest of tomato across Europe as it causes direct damage by feeding and indirect damage through virus transmission. Besides direct, plant-mediated, and natural enemy-mediated effects of climate change, whitefly biology is also affected by variations in endosymbiotic bacteria that they harbour.In our study, we will investigate the effects of physical consistent elevated CO2 levels and temperatures on multi-trophic interactions, including effects on the plant, insect pest, its natural enemies, and endosymbionts. Further, we will peer into the underlying mechanisms using RNA sequencing techniques and identify differentially expressed genes to gain a better understanding of how plants respond to climate change, whitefly colonization, and the combination of the two. To investigate what role endosymbionts might play in whitefly performance under modified climate conditions, we will use real-time quantitative PCR to get qualitative and quantitative information on endosymbiont presence under different climatic regimes. This will be a first study investigating the endosymbionts and their role in whitefly biology under future climate scenarios, in order to provide a comprehensive picture of multi-trophic interactions under climate change.The direct outcome of this study will be very comprehensive prediction of climate change effects on the very important global pest and their associated multi-trophic interactions. These predictions together with a detailed molecular understanding of plant’s biochemical responses to whitefly colonization under current and future environmental conditions will help create novel whitefly control methods. Additionally, these predictions are crucial in developing effective and sustainable climate change adaptation strategies for policy support as well as vegetable production.