The current project is to investigate how the RNAi mechanism is useful for one coleopteer model organism (Leptinotarsa decemlineata), Colorado potato beetle) to develop a control strategy. RNAi is the selective and gene-specific post-transcriptional inhibition of gene expression by endogenous expression or administration of dsRNA to the target cells or the target organism. The dsRNA which is complementary to the target gene will, once present in the cell, bind to the complementary mRNA and through a number of intermediate steps leading to expression inhibition. The underlying mechanism is largely unknown, but is most commonly defined into two parts: cell-to-cell autonomous and non-autonomous RNAi. In the first case occurs only expression-inhibition in the target cell, in the second case, the inhibition being passed to cells outside the original target cell. Non celautonome RNAi is further subdivided into ambient systemic RNAi and RNAi. Systemic RNAi includes all prrocessen where a '' silencing '' - signal from one cell to another is forwarded, possibly self from one tissue to another. Ambient-RNAi encompasses all processes in which dsRNA is taken up from the surroundings in a target cell. After recording in a multicellular organism, via ambient RNAi, RNAi can spread through the body via systemic RNAi. The latter is essential for use as a pesticide.