The book covers the advanced concepts and creative ideas on the postgenomic tool of RNAi that received the Nobel Prize in 2006. Emphasis was placed on the mechanisms of RNAi, the core machinery and the applications in agriculture. This book covers contributions from academia, industry and Government regulatory authorities. Applications to control major important pest insects, as for example western corn rootworm with use of transgenic plant RNAi. But also attention was given to the use of RNAi as a spray (non-transgenic plant approach) or tree-injection. Examples include the control of Colorado potato beetle and treatment of citrus trees to control Asian citrus psyllid. Additionally, the aspect of biosafety and risk assessment were also covered in the book with input from the bioinformatics and risk assessment testing, combined with regulatory input from EPA-USA and EFSA-EU. In summary, the editors believe that this book provides for the first time an invaluable vast source of basic and applied information for a plethora of scientists in academia, industry, and regulatory, as well as a textbook for graduate and advanced undergraduate students.