Biological diversity (or biodiversity in short) is the number, variety and variability of all living organisms in terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are parts (UNCED, 1992). Conceptually, it encompasses both the number (stock and information contained therein) and variability dimensions (Wale, 2004). Agro-biodiversity is a subset of biodiversity relevant for agriculture and it covers the variability of plants, animals and micro-organisms. It can be considered at three levels, i.e. genetic, species and agro-ecosystems (Upreti and Upreti, 2002). It encompasses various biological resources tied to agriculture including edible plants and crops, livestock and fish, naturally occurring insects, bacteria and fungi, agro-ecosystem components, wild resources of natural habitats and landscapes, and the genetic resources contained therein (Thrupp, 2000). Crop diversity is a subset of agro-biodiversity relevant for crop production. All the above terms have been used in this book as relevant.