Abstract: The Cydia pomonella Granulovirus (CpGV) is widely used for the control of codlingmoth (C. pomonella) many apple growing regions worldwide. In recent years development ofresistance to CpGV was observed in several European countries. On the other hand, new CpGVisolates overcoming this resistance were identified and applied in orchards with resistance. Tounderstand better the interaction between CpGV and its host and to determine the genetic factorsinvolved in the virulence of the virus the transcriptome of the virus and the expression profile ofits genome is analysed. By quantitative reverse transcription PCR (qRT-PCR) analyses, thespecific time frame of the infection process in midgut and fatbody tissue shall be discovered. Theaim of this project is to find new ways of virulence management by expanding the knowledge onthe gene regulation of CpGV in susceptible and resistant codling moth.