Biodiversity includes the whole range of life's varieties from wild eco-system to the genetic diversity of the domesticated agricultural crops. Biodiversity is the result of millions of years of evolutionary history. Human cultural diversity had co-evolved, in the recent geological past, along with biodiversity influencing considerably the course of the latter. Biodiversity is being lost at present more rapidly than at any time during the past. Based on this fact scientists predict that enormous number of both plant and animal species could be extinct in the near future. It is important to conserve species’ richness and genetic diversity within species for ecological rejuvenation. Discussing the value and importance of biodiversity, the World Charter for Nature adopted the policy, "…that every form of life is unique and warrants respect regardless of its worth to human beings." The highest level of biodiversity and the richest pools of genes are located almost exclusively in the tropical and sub-tropical areas of the Third World. The alarming rate of deforestation of the tropical rain forests leads to the destruction of habitat which harbours wild progenitors and weedy forms of other basic food plants. The other factors, which are threatening the biological diversity of the planet, are the irrational exploitation of plant and animal species and the biological invasions like notorious weeds. It is increasingly realised that loss of species and erosion of genetic material is a serious threat to sustain the development of humanity at large and to meet the changing human needs, in particular, including as yet unknown needs of future generations. The human race meets all of its food needs, and other needs as well, from both the wild and domesticated biological resources and this is largely possible because of biodiversity including the agriculture related diversity. The concept of sustainable agriculture becomes more important in the context of biodiversity which is essential to meet the current and future demands. Since the expansion of land to suit the agriculture needs reached the saturation point. The future increase in the production of agricultural crops to meet the food demand could be achieved only through the application of improved varieties with the required biotechnological advance. This, in itself, is antagonistic to the concept of conservation of local cultivars and Swaminathan calls them folk-cultivars. Genetically diverse species and wild relatives of major and minor crops provide sources of parental raw materials for plant breeding; these genetic resources are also encompassed with genes for imparting tolerance/ resistance to biotic and abiotic stresses and for development of cytoplasmic male sterile systems (CMS). Ironically many of the high yielding varieties are prone to attack by a number of pests and diseases which hamper the overall production markedly. More than 20,000 species of pests destroy a third of the total world food production annually. To avoid or minimize this loss, control strategy can be evolved using plants with genetic resistance to pests and diseases which are relatively cheap and also environmentally sound. The extreme homogeneity brought about by the universal adoption on vast area of cultivation of few crop varieties and the green revolution have accelerated the loss of species which were being cultivated as a part of the agricultural systems. It is often pointed out that the technological bind of improved varieties is that they eliminate the resource on which they are based. It is also said that the gene pools most likely to prove immediately useful in bio-technological applications are threatened more by the spread of modern crop-varieties to existing fields than by clearing of new land. So, plants which could withstand biotic and abiotic pressures better and forming the key for sustainability in agriculture is being lost with greater homogenization. Developments in the field of biotechnology have enhanced the scope of locating and transferring useful genes from wild species to cultivated crops and creating a novel gene combination. So, conserving and enhancing germplasm is an essential factor for sustainable agriculture. Cultural diversity: Cultures of different societies/communities are a maze of practices based on sets of values. These practices are acquired over a long period of time getting patterned into customs. They are enmeshed into several institutional frameworks. Thus cultural diversity is institutionalised. Biodiversity: Biodiversity means the variability among living organisms from all sources and the ecological complexes of which they are a part. Cultural practices in terms of agricultural and forest-resource utilization practices provide the variations in biological preservation and sustain biodiversity. Cultures are basically viewed as alternate ways of life. Cultural diversity is also basically a survival mechanism. The basic argument here is quite simple. Culture as a worldview and creator of values and a guide to practices, provides for distinct utilization and preservation of different biological species. Cultures provide the basis for sustainable biological diversity. In fact it could emphatically be said in this context that without cultural diversity sustaining biodiversity is not possible. In essence, it also means that respect for cultural pluralism will go a along way in sustaining biodiversity. The same argument could also be stated, perhaps, from a biodiversity-centric point of view. Biodiversity is used to create uniformities and homogenisation such as crop varieties. Monocultures displace local cultivars. Thus homogenisation of crop varieties works antagonistic to the principle of biodiversity. Homogenisation uses biodiversity but tries to displace biodiversity and hence non-sustainable in the long run. The Irula of Dharmapuri district, the Alu Kurumba of Nilgiris and Malayali of Kolli Hills in Tamil Nadu are a set of cases which bring out the agri-horticultural and forest-based activities and cultural practices. The remarkable way by which these groups of people preserve the local cultivars and the forest-species diversity ---so vital to biodiversity--- including the medicinal herbs in their natural state, is a case in point. The second set of case studies are those of the agricultural communities in the coastal areas of Andhra Pradesh and Tamil Nadu. They have traditionally been combining agriculture and culturing of fish. Thus they have been contributing to the marine eco-system preservation. The increased shrimp-culture in recent times has totally destroyed the delicate balance between the coastal-ecology and land-based agri-pisci cultural activities.