The chemicals from plant sources, generally termed as phytochemicals, play an important role in acceptance or rejection of the plant by the pests as they could be distasteful or toxic on one hand or on the other hand specialist herbivores have the capability to feed on many such chemicals, as they are able to process these natural products in a manner that is beneficial to them. In the wake of increasing environmental degradation due to burgeoning synthetic chemicals, there has been a process going on to rediscover the usefulness of plants and herbs and a continued effort for more than 2 decades has been to study the green products for cures for several ailments and pest management. In fact, according to Indian Medicinal Plants: A Sectoral Study, the global trade for medicinal plants amounts to about US $ 60 billion and the world demand continues to grow at the rate of 7 per cent per annum. Although many such plants are known in literature, neem has been one of trees with mani-fold virtues. Indian neem tree, Azadirachta indica A. Juss, which is a large evergreen tree, is an outstanding example among plants that has been subject matter of numerous scientific studies concerning its utilization in medicine, industry and agriculture. So far neem preparations have been evaluated against more than 500 species of insects and more than 400 hundred are reported to be susceptible at different concentrations.

The chemicals from plant sources, generally termed as phytochemicals, play an important role in acceptance or rejection of the plant by the pests as they could be distasteful or toxic on one hand or on the other hand specialist herbivores have the capability to feed on many such chemicals, as they are able to process these natural products in a manner that is beneficial to them. In the wake of increasing environmental degradation due to burgeoning synthetic chemicals, there has been a process going on to rediscover the usefulness of plants and herbs and a continued effort for more than 2 decades has been to study the green products for cures for several ailments and pest management. In fact, according to Indian Medicinal Plants: A Sectoral Study, the global trade for medicinal plants amounts to about US $ 60 billion and the world demand continues to grow at the rate of 7 per cent per annum. Although many such plants are known in literature, neem has been one of trees with mani-fold virtues. Indian neem tree, Azadirachta indica A. Juss, which is a large evergreen tree, is an outstanding example among plants that has been subject matter of numerous scientific studies concerning its utilization in medicine, industry and agriculture. So far neem preparations have been evaluated against more than 500 species of insects and more than 400 hundred are reported to be susceptible at different concentrations.

Poverty continues to persist in many countries throughout the world despite the improvements in the global trade regime and significant enhancement in agricultural productivity through the green revolution technologies. To achieve the millennium goal of halving poverty by 2015, these people should be provided with alternative production opportunities that can generate new employment and enhance incomes. Data from several countries reviewed in this study confirm that agricultural diversification can contribute to this. In a scenario of shrinking land and depleting water resources, the challenge of the new millennium is to increase biological yields to feed the ever-growing population without destroying the ecological foundation. It is thus important not to package this challenge as a demand or imposition on farmers, for which they would bear the cost, but as a necessity and methodology to also sustain their welfare. This book deals with different practices in agriculture diversification. Care has been taken to include applied aspects and present scenarios of different practices necessary for diversification of the agriculture. The book will be of use to students, researchers and progressive farmers.