ABC transporters in insect detoxification pathways Almost half of all insects in the world feed on plants; however plants exploit defense mechanisms of both physical and chemical nature such as secondary metabolites. Insects on the other hand have developed ways to circumvent these defense barriers for example by detoxifying the secondary metabolites through metabolism and excretion. Furthermore herbivorous insects encounter additional challenges such as insecticides. A suitable instrument to overcome both obstacles may be the multigene family of ATP binding cassette (ABC) transporters which comprises eight subfamilies encoding for transmembrane proteins that actively export a wide range of substrates out of the cell. These proteins have been associated with various functions in eukaryotes and prokaryotes; however information in insects is scarce. Therefore the aim of this thesis was to identify ABC transporters in lepidopteran herbivores and to investigate their role in insect detoxification pathways in relation to insect plant adaptation mechanisms as well as their role in insecticide intoxication. The role of ABC transporters was characterized on a genomic as well as a transcriptomic level (RNAseq) in different lepidopteran species. These results provide fundamental insights into the detoxification mechanism of insects focusing on insect plant adaptations. In addition one candidate gene was functionally characterized regarding its role in the Bacillus thuringiensis (Bt) toxin mode of action. This illustrates that ABC transporters are not only involved in detoxification mechanisms but also support intoxications. Beyond this knowledge will support the future development of new pest management strategies in agriculture.