eChapters

Introduction

Prebiotics are non-digestible food ingredient which beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of health-promoting bacteria in the intestinal tract, thus improving the host‘s microbial balance (Gibson and Roberfroid, 1995). Normally, prebiotics contain some type of a non-digestible carbohydrate fraction (Rehman et al., 2009). Almost 90% of oligosaccharides escape digestion in the small intestine and reach the colon where they selectively stimulate the growth and/or activity of beneficial bacteria like Bifidobacteria, Lactobacillus and Streptococcus, providing prebiotic properties (Stanton et al., 2003). These bacteria populate the gut filling any niches were pathogenic bacteria may attempt to take hold. This concept is better known as competitive exclusion. Prebiotics function by lowering the gut pH through lactic acid production, inhibiting/preventing colonization of pathogens, modifying metabolic activity of normal intestinal flora, and stimulation of the immune system (Doyle and Erickson, 2006). Studies have demonstrated that these bacteria reduce pathogenic bacteria like Salmonella spp., Clostridium diffile and Campylobacter spp. (Hopkins and Macfarlane, 2003; Stern et al. 2000), by diverse mechanisms including competitive exclusion of nutrients or adhesion sites to intestinal mucosa (Stern et al. 2000) and fatty acid of short chain production, like propionic and butyric acids, which modifies the acidic conditions and inhibits the growth of microorganisms that cause infections (Collins and Gibson, 1999).

Introduction

Synbiotics refer to nutritional supplements combining probiotics and prebiotics in form of a synergism. The synbiotic concept was first introduced as “mixtures of probiotics and prebiotics that beneficially affect the host by improving the survival and implantation of health-promoting bacteria. Probiotics are live bacteria which are intended to colonize the large intestine and confer physiological health benefits to the host. A prebiotic is a food or dietary supplement product that enhances the activity of probiotics. Synbiotics are not drugs and the effects are due to changes in bacteria population or enhancement of activity of the bacteria. A synbiotic may contain fiber, but all fiber is not necessarily a synbiotic.

Using prebiotics and probiotics in combination is often described as synbiotic, but the United Nations Food & Agriculture Organization (FAO) recommends that the term “synbiotic” be used only if the net health benefit is synergistic. A synbiotic contains fiber such as fructose oligosaccharide, galactose oligosaccharide, etc. and is intended to stimulate the microflora in the large intestine. The combination of probiotics and prebiotics work separately in the small and large intestine, but synergistically increase the overall gut health. Prebiotic has shown to increase the population and/or function of the probiotic it is paired with, as the probiotic is an external species, whereas prebiotics stimulate the flora which is already present.

Introduction

With the perception that antibiotics should no longer be used as animal growth promoters, there has been widespread interest in natural methods of inhibiting detrimental bacteria. Their removal from the poultry diets is therefore brings with it consequences. This has lead to somewhat of a renaissance in research activity on the discovery and application of non antibiotic chemical compounds capable of either killing microorganisms outright or at the very least retarding growth sufficiently to limit their dissemination. Organic acids have a long history of being utilized as food additives and preservatives for preventing food deterioration and extending the shelf life of perishable food ingredients. In recent past organic acids have been used to control microbial contamination and replace antibiotic growth promoters in poultry (Ricke, 2003; Hassan et al.,2010; Adil et al., 2011).

Introduction

After the discovery that low concentrations of antibiotics included in livestock diets had a beneficial effect on production efficiency, the use of antibiotic growth promoters (AGPs) became a common practice, benefiting both the livestock industry and consumers. Antibiotic growth promotion in agricultural and animal production has been practiced for about 50 years (Dibner et al., 2007). Orally ingested antibiotics promote growth and efficiency of poultry and other animals. Early indications of a beneficial effect on production efficiency in poultry and swine were reported by Moore et al. (1946) and Jukes et al. (1950).

Introduction

An ionophore is a lipid-soluble molecule usually synthesized by microorganisms, which transport ions across cell membranes of susceptible bacteria, dissipating ion gradients and uncoupling energy expenditures from growth to kill these bacteria. The term ionophore was first used in 1967 for their ability of organic molecules to bind metal cations and form lipid soluble complexes that facilitate their transport across cell membrane. The ionophore antibiotics show wide varieties of biological activity ranging from antibacterial, antifungal, antimycoplasma, antiparasitic, antimalarial, antiviral, anti-inflammatory and tumourcell cytotoxic activity (Augustine, et al., 1987; Gumila et al., 1996). Presently seven polyether antibiotics include monensin, lasalocid, salinomycin, narasin, maduramycin, laidomycin and senduramycin are used around the world in various segments of cattle and poultry industries. These ionophores are mainly used as anticoccidial drugs in poultry and growth promoters in the ruminants. Polyether antibiotics are not used in human but recently, it has been shown that some of these compounds are able to selectively kill human cancer stem cells and multidrug resistant cancer cells. Hence, they are recognized as new potential anticancer drugs.

Introduction

To improve the growth and health status, addition of antibiotics in the poultry feed was a common practice in last decade. Currently, in developed countries it is banned due to fatal consequences like development of antimicrobial resistant organism pool in the gut, persistence of antibiotic residue in the food chain that can reduce the food safety level. Therefore, various alternatives are now a day thought to use as poultry feed additives. Immunomodulaors are presently receiving wide attention as feed additives.

The term ‘immunomodulation’ is generally used to describe the manipulation of immune system which consists either increase (immunostimulation) or decrease (immunosuppression) in the magnitude of the immune system function. The chemicals or biological substances producing this phenomenon are known as ‘immunomodulators’. Specific immunomodulation involves the change in the immune response with a particular antigen (e.g. vaccination). Whereas, non-specific immunomodulation alters the immune response in such a way so that it become sensitive to a wide range of antigens. Generally this kind of non-specific immunomodulators are used as poultry feed additive to increase the resistance against the wide range of infections. The principal components of the immune system targeted for immunomodulation include T cells, B cells, monocytes, macrophages, granulocytes and natural killer cells (Dalloul and Lillehoj, 2005).

Introduction

There is concern that antibiotic-resistance in bacteria may make commonly used antibiotics less effective. Oral immunotherapy (passive immunization) with specific antibodies is a strategy that has been actively pursued in laboratory and clinical studies for the last two decades. Feeding of egg yolk antibodies to neutralize specific pathogens, especially enteric microorganisms, is a potential alternative to antibiotics. Oral administration of these antibodies has met with some degree of success in prevention of viral and bacterial enteric infections in humans, piglets, calves, fish and rabbits. It is proposed that the egg yolk antibodies may act against enteric pathogens by binding, immobilising and consequently reducing or inhibiting the growth, replication, or colony forming abilities of these pathogens. Three immunoglobulin classes (IgA, IgM and IgY) have been shown to exist in chickens. Chicken immunoglobulin G (IgG) has been designated as immunoglobulin Y(IgY) because it varies in several aspects from mammalian IgG. IgY is the main serum immunoglobulin in chickens. It is transported from the hen to the embryo via the egg yolk. The egg yolk thus contains high concentrations of IgY. Other immunoglobulin (Ig) classes are present only in negligible amounts in the egg yolk. It has been shown that the presence of immunoglobulins in eggs is an example of passive immunity. This is because these antibodies originated from the hen and are used to protect the offspring from various infectious diseases after hatch.

Introduction

Coccidiosis is the most economically harmful disease encountered in commercial poultry production. It is caused by single celled protozoan parasites of the genus Eimeria which are commonly referred to as coccidia. Williams (1998) reported that the annual worldwide loss is about $ 800 million. The total loss due to coccidiosis is found to be Rs. 1.14 billion in India. The important finding is that almost 70 percent of the estimated cost is due to subclinical coccidiosis, by impact on weight gain and feed conversion rate. One of the reasons for these remarkable finding is probably the difficult diagnosis of subclinical coccidiosis.

Chickens are susceptible to at least seven species of Eimeria. The most common species are Eimeria tenella, which causes the caecal coccidiosis, E. necatrix &E. maxima, which causes mid intestinal coccidiosis, E. acervulina which causes anterior intestinal coccidiosis and E. brunetti which causes posterior intestinal or rectal coccidiosis. E. mitis and E. praecox are generally mildly pathogenic and commonly occurring as co-infection/mixed infection in with other species. Coccidiosis is particularly difficult to combat because several different species of Eimeria exist in the field. Poultry may become infected with different species because the immunity that develops after infection is specific only to one species. Eimeria has direct and complex life cycle that involves many developmental stages within the host cells. Each Eimeria species has characteristic intestinal lesions and type of diarrhoea (with or without blood).

Introduction

For the past few decades, a number of chemical feed additives such as antibiotics, ionophores, methane inhibitors and defaunating agents have been introduced into ruminant nutrition in order to improve rumen fermentation, and increase growth and milk production by improving intake and feed conversion efficiency. However, most of these supplements are not used routinely because of toxicity problems to the host animals and microbial adaptation to these additives. Most importantly, growing awareness from public health aspects has centered on the safety of tissue residues of these chemicals and also bacterial resistance to antibiotics as a result of increased use in the food chain. These supplements have been criticized by the consumers’ organizations on the ground of product safety and quality. Antibiotic feed additives are banned in European Union. The consumers’ demands have drived the search for natural alternatives to chemical feed additives for eco-friendly animal production. Plants are part of herbivore diets, and these plants contain bioactive compounds with antimicrobial properties can be of interest in animal nutrition. Therefore, recent research has been greatly focused to exploit bioactive plant secondary compounds as natural feed additives to improve rumen fermentation such as enhancing protein metabolism, decreasing methane production, reducing nutritional stress like bloat, and improving animal health and productivity (Wallace et al., 2002; Patra and Saxena, 2009a, b; 2010; 2011), which may be useful in eco-friendly livestock farming (Patra, 2007). This review discusses the effects of different plant metabolites on rumen fermentation, rumen microbial ecosystems and ruminant performance.

Introduction

There is growing worldwide interest in reducing methane emissions from domestic ruminants. Methane is a potent greenhouse gas and its release into the atmosphere is directly linked with animal agriculture, particularly ruminant production. Methane emitted from ruminant livestock is regarded as a loss of feed energy and also a contributor to global warming. Methane is synthesized in the rumen as one of the hydrogen sink products that are unavoidable for efficient succession of anaerobic microbial fermentation. Various attempts have been made to reduce methane emission, mainly through rumen microbial manipulation, by the use of agents including chemicals, antibiotics and natural products such as oils, fatty acids and plant extracts. A newer approach is the development of vaccines against methanogenic bacteria. While ionophore antibiotics have been widely used due to their efficacy and affordable prices, the use of alternative natural materials is becoming more attractive due to health concerns regarding antibiotics. An important feature of a natural material that constitutes a possible alternative methane inhibitor is that the material does not reduce feed intake or digestibility but does enhance propionate that is the major hydrogen sink alternative to methane. Since methane contains energy, its emission during rumen fermentation is considered to be a loss of feed energy that is equivalent to 2-12% of the gross energy of animal feed (Johnson and Johnson, 1995). Some implications of these approaches, as well as an introduction to antibiotic-alternative natural materials and novel approaches, are provided.

Introduction

Ruminants are provided with a microbial ecosystem in the gastro-intestinal tract which helps in the bioconversion of lignocellulosic feeds into volatile fatty acids which are utilized by the animal as a source of energy. This microbial biomass is also helpful in synthesis of microbial protein and B-complex vitamins for the host animals. Any disturbance in the microbial balance may affect the performance of the animal adversely and any improvement in the microbial environment may lead to the improvement in productivity of the animal. A number of chemical feed additive like hormone, antibiotics have been used to improve the performance of the animals. But due to residual left over in the animal products and risk of creating disease, resistance against antibiotics, the use of these chemical feed additives have been discouraged and even banned in some countries. As an alternative microbial feed additive seems to be more natural; as it is not creating any new thing in GIT but it is merely restoring the normal and ideal flora in the digestive tract to its full capacity.

Introduction

The original concept of feeding bacterial direct fed microbial (DFM) to livestock was based primarily on potential post–ruminal effects, including improved establishment of beneficial gut microflora (Fuller, 1999). Calves fed Lactobacillus acidophilus have been reported to have reduced incidence of diarrhoea (Beecham et al., 1977) and reduced intestinal coli form count (Bruce et al., 1979). But now it is known that certain bacterial DFM also have beneficial effects in the rumen and one of the important groups of this type of bacteria is propionic acid producing bacteria (Elsden, 1945; Johns, 1951a; Langa, 2010). This group of bacteria includes Propionibacterium spp., Veillonella spp., Megasphaera spp., Selenomonas spp. and Succiniclasticum spp. (Table 1). Propionic acid producing bacteria (PAPB) are secondary bacteria which enhance propionate production by utilizing the end products of primary fibrolytic or starch utilizing bacteria which produce succinic acid and lactic acid (Swenson and Reece, 1996). Inoculation of in vitro fermentation with the lactate utilizing ruminal bacterium Megasphaera elsdenii prevented lactate accumulation and produced propionic acid when a highly fermentable substrate was used (Kung and Hession, 1995). Propionibacteria are also rumen active bacteria which can produce propionic acid by utilizing glucose, lactic acid and succinic acid (Elsden, 1945; Grinstead and Barefoot, 1992; Hugenholtz et al., 2002). Ghorbani et al. (2002) also reported that Propionibacteria convert lactate and glucose to acetate, propionate and CO₂. They also reduce nitrate to nitrite and reduce nitrite load by 40-60% and minimize changes in blood nitrite and met hemoglobin (Rehberger et al., 1993). Succinic acid is an important end–product, but in practice this is converted into propionic acid by other bacteria such as Selenomonas ruminantium (Swenson and Reece, 1996; McDonald et al., 2002; Langa, 2010); such interactions between microorganisms are an important feature of rumen fermentation. Veillonella gazogenes are also active in the rumen and produce propionic acid by fermenting succinic acid (Johns, 1951a). Moreover in low quality forage-based diet Fibrobacter succinogenes are predominant fibrolytic bacteria which digest fibre faster and produce sufficient amounts of succinic acid in the rumen (Cheng et al., 1984; Miron and Ben-Ghedalia., 1992) and synergistic increases in propionate production and fiber digestion was found in co-cultures of Fibrobacter succinogenes and Selenomonas ruminantium (Sawanon et al,2003), and of Ruminococcus flavefaciens and Selenomonas ruminantium (Sawanon et al., 2006). These findings suggest that positive interactions occur between bacteria, mostly via metabolite exchange.

Introduction

The process of making the rumen of animals free of rumen protozoa is called defaunation and the animal is called defaunated animal. The role of rumen ciliate protozoa on the performance of host animals became debatable issue when Becker and Everett (1930) demonstrated that rumen protozoa were non-essential for growth in lambs. Nevertheless, the reports of recent years reflect that though protozoa may be non essential for ruminant, still they have significant role to play in the rumen metabolism specially to stabilize the rumen pH (Santra and Karim, 2002a). Rumen protozoa are the largest in size among rumen microbes and contribute 40-50% of the total microbial biomass and enzyme activities in the rumen (Agarwal et al., 1991).

Introduction

Enzymes are globular proteins that act as biological catalysts. They are produced by living cells to bring about specific biochemical reactions. Digestive enzymes catalyze the degradative reactions by which substrates (i.e., feedstuffs) are digested into their chemical components (e.g., simple sugars, amino acids, fatty acids) which in turn, are used for different body functions. Different enzymes are utilized for the complete digestion of complex feed. The enzymes are being used in the feeding industry from last several decades. Various digestive enzymes have been studied for use as feed additives to enhance animal performance They are commonly used to improve the nutritive value of feeds for non-ruminants (especially, poultry and swine). They are not routinely used in adult ruminant diets because the fibrolytic activity within the rumen environment is normally very high, and it is assumed that exogenous enzymes cannot survive proteolysis in the rumen (Kopency et al., 1987). Forages are the main feed component that serve as the major source of energy available to the animal in ruminant production system. However, due to slow or incomplete digestion of fibrous substrates only 10 to 35% of energy intake is available as net energy that significantly limits livestock performance and profits in production systems. To improve the ruminal fibre degradability many strategies have been developed to stimulate the digestion of the fibrous components in ruminant feeds. That includes, use of various feed additives which stimulates fiber digestion, physical and chemical processing of feeds in order to enhance the rate and extent of fiber digestion. However, the use of “natural” product to enhance production efficiency is highly recommended that can potentially play some role in replacing performance benefits vacated by antibiotics and hormones. Enzymes are proteins that are ultimately digested or excreted by the animal, leaving no residues in products, which was a major drawback in the use of antibiotics and hormones.

Introduction

While world population is expected to increase from 6 billion to about 8.3 billion, India is likely to be the most populous nation with 1.6 billion in the year 2030. Therefore, it is essential to be prepared to produce sufficient food for the increased population with the application of newer technologies. The consumption of animal food was 10 kg/yr in the 1960s increasing to 26 kg/yr in 2000 and is expected to be 37 kg/yr by 2030 (FAO, 2008; 2009). Large increases in per capita and total demand for meat, milk and eggs are forecast for most developing countries for the next few decades (Delgado et al., 1999). In developed countries, per capita intakes are forecast to change slightly, but the increases in developing countries, with their larger populations and more rapid population growth rates, will generate a very large increase in global demand.

Moreover, an increasing number of consumers demanding healthy and quality foods have pushed researchers into development of technologies that can control the proportion of lean and fat muscle deposition in meat producing animals. A number of technologies have been developed that led to remarkable improvements in the efficiency of animal production and in carcass composition and meat quality. There are some dietary additives and vitamins that may increase protein and muscle deposition, while often simultaneously reducing fat deposition by modifying nutrient metabolism in individuals.

Introduction

For raising animal and its products especially protein, food and nutrition plays an important role. Feed cost comprises about 60% of total recurring expenditure. Feed additives play an increasingly important role in animal nutrition by augmenting the performance by maintaining the needs of essential nutrients, improving feed conversion therefore optimize feed utilization (Wenk, 2000). Feed additives are a group of feed ingredients that can cause a desired animal response in a non-nutrient role, such as rumen modifier, growth or metabolic modifier (Hutjens, 1991). These are used in micro quantities and require careful handling and mixing. The development and introduction of various new feed additives is a major and practical solution to improve the efficiency of animal production, to alleviate environmental pollution, to maintain animal health, welfare and to ensure the safe and of good quality food production.

Introduction

Growth enhancement technologies have been widely embraced in the livestock industry to improve growth, efficiency and carcass traits. For over 50 years, estrogenic and androgenic hormone implants were widely used in the cattle feeding industry, and it is estimated that approximately 97 percent of feedlot cattle in the U.S. receive one or more implants during the finishing phase (Barham et al., 2003; Tatum, 2006). There is a large body of literature that indicates the positive growth enhancement effects which implants impart on growing and finishing cattle and producers have extensively used implants to increase live body weight, improve average daily gain and feed efficiency, and reduce the number of days cattle are on feed (Apple et al., 1991; Duckett et al., 1997;Milton and Horton, 1996; Perry et al., 1991). Likewise, there is a growing body of literature that indicates the positive response on growth and carcass characteristics that finishing cattle have to beta-adrenergic agonists. The hog industry, and more recently, the cattle feeding industry have increased utilization of beta-adrenergic agonists to improve the efficiency of production. While the use of Ractopamine hydrochloride (Paylean^®, Elanco Animal Health, Greenfield, Indiana) has been used extensively in hog production since its approval by the Food and Drug Administration (FDA) in 1999, similar pharmaceutical feed additives have only recently been implemented in commercial cattle feeding operations. Beta-adrenergic agonist use in fed cattle has substantially increased following the FDA approval of Ractopamine hydrochloride (Optaflexx^®, Elanco Animal Health, Greenfield, Indiana) in 2003, and the approval of Zilpaterol hydrochloride (Zilmax^®, Merck Animal Health, Summit, New Jersey) in 2006. The use of both Ractopamine hydrochloride (RH) and Zilpaterol hydrochloride (ZH) have shown to elicit similar improvements in live weight gain, average daily gain, and feed efficiency as those reported in hormone implants (Allen et al., 2009; Avendano-Reyes et al., 2006; Beckett et al., 2009; Elam et al., 2009; Gruber et al., 2007; Kellermeier et al., 2009; Scramlin et al., 2010). In addition, these compounds have been reported to have profound effects on hot carcass weight, Longissimus muscle area and carcass cutability (Gruber et al., 2007; Hilton et al., 2010; Rathmann et al., 2009; Scramlin et al., 2010; Shook et al., 2009; Vogel et al., 2009). It is because of this that cattle feeders have drastically increased use of beta-agonists since their FDA approval, and a growing portion of the fed cattle population receive a dietary beta-agonist supplement that is provided within the final 20 to 30 days of finishing.

Introduction

Supplementary feeding is an essential practice in fish farming operation which accounts for over 60% in total input cost. The dependence of candidate species on balanced supplementary feed increases with increase in stocking population in ponds targeting per hectare higher production as the standing crop of cultured species exceeds the natural feeding capacity of ponds. Therefore, feeding of artificial feed balanced in all nutrients such as protein, lipid, carbohydrate, vitamins and minerals containing optimum protein and energy ratio has assumed foremost importance in aquaculture industry. The use of balanced feed however, is directed towards optimum realization of genetic potentials of farmed species for survival, immunity, growth and reproduction (Mohanty, 2009). Consequent to researches done in India and abroad, a strong data base has been developed about the nutritional behavior of great majority of these cultivable fish and shell fish species and several feed formulations have been successfully undertaken. With optimum pond management, feeding of formulated balanced feed, it has been possible to increase aquaculture production as high as 15- 17 t/ha/yr for carps and 8-12 t/ha/yr in semi intensive prawn and shrimp farming in India (Mohanty, 2009).

Introduction

Public concern over use of antibiotics in livestock production has increased in recent years because of their possible contribution to emergence of antibiotic resistant bacteria, and their transmission from livestock to humans. Accordingly, ruminant microbiologists and nutritionists have been exploring alternative methods of favorably altering ruminal metabolism to improve feed efficiency and animal productivity. Plant extracts contain secondary metabolites, such as essential oils (EO) that have antimicrobial properties that make them potential alternatives to antibiotics to manipulate microbial activity in the rumen. Essential oils are naturally occurring volatile components responsible for giving plants and spices their characteristic essence and color. Over the last few years, a number of studies have examined effects of EO, and their active components, on rumen microbial fermentation. However, many of these studies are laboratory based (i.e., in vitro) and of a short-term nature. Nevertheless, results from in vitro batch culture studies provide evidence that EO and their components have the potential to improve N and/or energy utilization in ruminants. Effects of EO on ruminal N metabolism is more likely mediated by their impact on hyper-ammonia producing (HAP) bacteria resulting in reduced deamination of amino acids (AA) and production of ammonia N.

Introduction

Plant products have been used for centuries by humans as food and to treat ailments. Natural medicinal products originating from herbs and spices have also been used as feed additives for farm animals in ancient cultures for the same length of time. Keeping farm animals healthy is necessary to obtain healthy animal products. The main scope in animal husbandry is to ensure good performance of farm animals and get quality animal products, which can be achieved only with the effort to keep the animals healthy. Only quality feed together with proper hygiene, potable water and management can ensure the production of nutritious animal products with desired organoleptic properties (Saxena, 2008). A ban of antibiotics as feed additives in animal nutrition is realized since 1986 in Sweden and later on to various countries. A general ban is foreseen in some years from now, because of the increased occurrence of pathogens resistant against therapeutical antibiotics used in animals and humans. With the restricted use or ban of dietary antimicrobial agents we must explore new ways to improve and protect the health status of farm animals, to guarantee animal performance and to increase nutrient availability (Wenk, 2003). In this aspect, herbs and spices are not just appetite and digestion stimulants, but can, with impact on other physiological functions, help to ensure good health and welfare of the animals, what can positively affect their performance.

Introduction

Mycotoxins are substances produced by fungal infections which in some cases do protect plants or plant seeds against parasites (Schardl et al., 1996). However, upon ingestion, inhalation or dermal contact, these mold producing substances are poisonous to vertebrates. Even with more than 100,000 species of fungi known, only some of them are active mycotoxin producers. The fungi species which are known to produce the most hazardous mycotoxins in agriculture and in animal production are Fusarium, Aspergillus and Pencillium spp. Mycotoxins vary greatly regarding their toxicological effects as they do not belong to a single class of chemical compounds (Jewers, 1987). The environmental conditions in which they are preferably produced also differ. Fusarium toxins, such as trichothecenes, Zearalenone and fumonisins are commonly produced on the field, whereas aflatoxins and ochratoxins are produced by Aspergillus and Penicillium spp. mainly after harvest and during poor storage conditions.

Introduction

Plant pests have been a part of the man’s environment, since ages. Traditional agriculture which included diverse crops and indigenous crop management practices provided little opportunity for the pests to build up and spread rapidly (Smith and Allen,1954). Crop production is constantly threatened by increasing difficulties in controlling insect pests, which are a major impediment to improved livelihoods of the poor farmers. However, in the quest for increasing food production for the growing population, use of pesticides became a norm in crop management. Pesticides became an integral part of the process owing to losses from weeds, diseases and pests reducing the harvestable produce. Use of pesticides along with high yielding varieties, irrigation and improved seed did result in increased productivity. But the rampant use of these chemicals, under the adage, “if little is good, a lot more will be better” has played havoc with human and other life forms.

Introduction

Integrated Pest Management (IPM) has evolved over the last five decades since Stern et al. (1959) first gave the concept of integrated control. The basic tactics of IPM were developed and applied to reduce crop losses against the ravages of pests before the term IPM was coined (Jones, 1973; Smith et al.,1973). Entomologist at the university of California, United State of America (USA) played a pivotal role in developing IPM tactics (Perkins, 1982). Development of resistance to insecticides and the elimination of natural enemies by insecticides led to the development of ‘supervised control’. The publication of the book ‘Silent Spring’ written by Rachel Carson (1962) was a defining milestone for it brought the problems caused by pesticides to the attention of the public and the scientists. The term ‘integrated pest management’ was used for the first time by Smith and van dan Bosch (1967). In the last five decade many synthetic pesticides have been banned. In 1972, ’integrated pest management’ and its synonym were incorporated into English dictionary and accepted by the scientific community (Kogan, 1998). IPM is the main strategy accepted for pest management under agenda 21 of the United Nations conference on Environment and Development (UNCED, 1992).

Agriculture has always played and will continue to play a dominant role in the growth of Indian economy in the foreseeable future. It represents the largest sector producing around 28 per cent of the gross domestic product (GDP). Achieving self sufficiency in food grains production has ensured a high priority for agricultural sector in the successive development plans of the country. Agricultural production is grossly affected by attack of pests/diseases on various crops and the losses in food grains only are to the tune of Rs 90,000 crores each year in India. The prevention of such losses needs substantial consideration and accordingly forewarning of pests and diseases is essential for taking timely control measures. These are also required for assessing losses. Pest/disease infestation in crops is highly influenced by meteorological factors. The weather based modeling for early warning of pest/disease infestation may provide appropriate tool for investigating and predicting pest/disease status.

The steadily-increasing human population has led to a rise in the demand for food. As more land comes under agricultural cultivation there will be more pressure on natural ecosystems. Climate change will affect agricultural yield directly because of aberrations in temperature and rainfall, and indirectly through changes in soil quality, pests and diseases. In particular, the yield of cereals is expected to decline in India, Africa, and the Middle East. As the temperature rises conditions will become more favourable for pests such as grasshoppers to complete a number of reproduction cycles and thereby increasing their population. In the higher latitudes (in the northern countries) agriculture will benefit with the rise in temperature as the winter season will be shorter and the growing seasons longer. This will also mean that pests that will move towards the higher latitudes as the temperatures rise. Extreme weather conditions such as high temperature, heavy rainfall, floods, droughts, etc. will also affect crop production.

Introduction

Information technology is set to become important in agriculture in the coming years. In the last few decades, the application of computers and communication technologies has led to the development of a plethora of information of all types in the area of plant protection science. These information bases are available on CD-ROM, on-line form in various hosts and via mail over internet, multimedia data bases, Decision-Support Systems (DSS)/Expert Systems (ES), Simulation Models (SM), etc.- to cite a few of the latest developments. Further, cyber space is fast emerging as an area of information technology, particularly in the field of crop pest management (Srivastava and Swain, 1998). The application of information technology in pest management has been one of the most exciting developments in the field over the last decade. From the 1960s, the entomologists began using computers for spray scheduling, population modeling, exploring control strategies and managing pest monitoring data. More recently, computers are being utilized in pest management delivery systems and decision support systems (DSS) designed to enhance decision making.

Introduction

Taxonomy, which includes identification and classification has transformed into systematics and biosystematics in the recent times and is integrating itself into the biodiversity, which is now a global phenomenon occupying the main thrust of human life. The magnitude and cause of this biodiversity is the central problem of taxonomy and one of the key problems of science as a whole, not to speak of pest management. The science of taxonomy started in the late eighteenth century by a Swedish biologist, Carl Linnaeus who with a small number of similar minded scientists pioneered a standard system of using two Latin names for an organism, denoting “genus” and “species” that is still in use. This led to referring of biological organisms by an universally agreed name and identity, and further providing means for their realistic classifications. When these identifications and classifications got strengthened further with accumulated biological knowledge, it allowed the development of modern biology on a sustainable and stable base. In addition, in the recent times taxonomy has become more demanding subject for areas in science and technology, which are dependant on access to accumulated experience and knowledge for their survival and development. Insect pest management is one such area where taxonomy provides the essential scientific basis, without having any claims of its own and integrating itself in such a manner that its role is difficult to delineate precisely.

Introduction

Food security is an agricultural issue that has political connotations in the world and more strikingly so in the developing world, where systems of governance has assumed and lost power on this issue. Agriculture not only contributes to the overall growth of the economy but also provides a vital livelihood base, employment and food security to the majority of the country’s population. Recent food price hikes have drawn the attention of the world’s policy-makers and news media to food security which triggered a wide variety of policy responses throughout the world. It threatens the food crisis and livelihood of millions of peoples suffering from hunger and poverty.

Introduction

Huge population in the developing countries requires increased amounts of food and fiber from a shrinking agricultural land base. Intensification of agriculture through expansion of irrigation facilities, introduction of high yielding varieties and application of increased amounts of agrochemicals has been in progress. Besides, the cultural practices like spacing, crop rotations, sowing times and tillage methods have been modified to achieve maximum productively per unit time from the available land. However, along with various technological achievements, sever outbreaks of insect pests, diseases and weeds in agricultural crops have also occurred. Many hitherto unknown species have assumed serious status and some of the serious pests have developed resistance to one or more groups of pesticides. In addition, pesticides have contaminated different components of our environment and pose a potential health hazard to consumers. Therefore, the future pest problems will have to be tackled in an environmentally benign manner as a part of a sustainable crop production technology (Dhaliwal and Heinrichs, 1998; Koul et al., 2004; Koul, 2008).

Introduction

With the introduction of chemical pesticides in India during 1947 when 250 tonnes of DDT was imported for Malaria eradication programme, there is a steady increase in consumption and at present about 25 per cent of the cropped area is covered by pesticides. Their use has helped in increasing the productivity over the years. The consumption pattern of different groups of insecticides has indicated the same trend. The Indian pesticide industry with 85,000 MT of production in is ranked second in Asia (behind China) and twelfth globally. The Indian pesticides industry is dominated by insecticides where herbicides and fungicides are the key segments globally. Among the pesticides, insecticides account for 57 per cent, fungicide 28.7 per cent and herbicides 14.0 per cent during the year ending 1997-98. Owing to the ban of highly persistent organochlorine pesticides, there is decrease in the trend. Among the different crops, cotton consumes 44.5 per cent of the pesticide worth of Rs.2462.13 millions, even though it occupies only 5 per cent of the cropped area. Cotton is followed by rice (22.00% of pesticides) and other crops.

Introduction

One of the triumphs of modern agriculture is the increase achieved in the productiveness of land, measured by yield of crops per hectare or per acre. This has enabled the earth to support a much greater population than would have been possible in past centuries. The increased productivity of the land is a result of scientific and technological progress in plant breeding, in control of pests and weeds, in irrigation and in fertilizers to supplement natural reserves of plant foods. But this progress makes it more difficult to fulfill one specific requirement of many crops: pollination. Pollination of flowers is an essential step in the sexual reproduction of angiosperms. Most angiosperm species rely on insects or other animals, rather than wind, for transfer of pollen among individual plants. The pollinators in turn benefit by obtaining floral resources such as nectar or pollen. Pollination is not only mutually beneficial to the interacting plants and animals, but also serves humanity directly through the yield of many crops, and indirectly by contributing to the healthy functioning of unmanaged terrestrial ecosystems (Costanza et al.,1997; Nabhan and Buchmann, 1997; Klein et al., 2007; Abrol, 2007 and 2008).

Introduction

The increasingly precarious situation facing the world’s hill regions has been the focus of a growing level of awareness over the past two decades. The high altitude regions offer a challenge to agricultural development agencies which is shared by many hill areas of the world characterized by marginality, extreme diversity, environmental fragility and complex smallholder farming systems. There is justifiable concern relating to the conservation of hill and mountain ecosystems, to the extent that the concept of sustainability has been adopted as a broad slogan by the environmental movement (Lele, 1991).

Conditions specific to mountain regions, such as inaccessibility and diversity have placed a high premium on large families, encouraging population growth. Children are essential to family subsistence strategies offering free labour, and they are consequently considered to be a source of wealth. Population control measures in these regions have ignored this scenario (Sharma and Banskota 1990; Jodha, 1991).

Weeds pose serious problems to agriculture and environment. Weeds are plants that are undesirable to human activity at a particular time and place, and therefore, weeds will always be associated with human endeavours. In agriculture these not only cause huge reductions in crop yields but also increase cost of cultivation, reduce input efficiency, interfere with agricultural operations, impair quality, act as alternate hosts for several insect pests, diseases and nematodes. In non-crop areas, they affect aesthetic look of the ecosystem as well as native biodiversity and health and quality of life. Weeds are a big constraint in crop production and are responsible for heavy yield losses in almost all the crops. “Being fore-warned is fore-armed” is the principle behind preparation of perspective plans. Weeds are big constraints in crop production and are responsible for heavy yield losses in all crops. Out of the losses due to various biotic stresses, weeds are known to account for nearly one third. Proper management of weeds is essential to meet the growing demand of foodgrains, pulses, oilseeds and other crops by the ever increasing population. As per the projections of IFPRI, Washington there is a likelihood of shortfall of 41 per cent in the food grain production in the country by 2020.

Introduction

The main reliance is on the use of insecticides to reduce the losses. The insecticides are the major component of “Integrated Pest Management” (IPM) in almost all the agro-ecosystem. Cotton, paddy, vegetables and fruits are grown in 32% of the cultivated area and account for over 80% of the pesticide consumption in the country. From a modest beginning in 1947, when DDT was first used for malaria control, pesticide consumption in India has grown to a total market size of over Rs. 45000 million in 2003. The total installed capacity of technical grade pesticides is approximately 140,000 tpa. Out of the 204 pesticides registered in the country, 66 technical grade pesticides are manufactured in India.

Introduction

The integrated nature and high diversity of the soil health system may contribute a significant degree of resilience under conditions of disturbance, particularly at lower (largely microbial) trophic levels. Nonetheless, the conversion of natural vegetation to agricultural land results in major changes in both physical organization and community structure in the soil, including species loss and changes in dominance among the surviving biota. This then becomes the resource with which agriculture must work and any targets should realistically be set in relation to the potential equilibria in agricultural systems rather than the natural systems from which they are derived, as has sometimes been advocated. More importantly, it is clear that subsequent agricultural practices may also impair soil health through significant impacts on the composition and structure of the soil biological community and consequently on soil-based ecosystem functions and services. Damage to ecosystem functions can arise both owing to an inadequate supply of resources (carbon, energy, nutrients or water) and through the impact of intensive substitutive practices such as continuous mechanical tillage, the use of pesticides and excessive amounts of fertilizers. These interventions may also impact on soil functions by destroying or changing the habitat of the soil organisms and their capacity to repair it.

Introduction

The concept and impetus for IPM grew out of the discontent with using a purely insecticidal approach to insect control in many areas in the mid of twentieth century. Excessive use of pesticide and growing needs of people has triggered several consequences such as resistance and resurgence of pests, destruction and elimination of natural enemies, effect on non target organisms, environmental pollution, disruption in food cycle and food web and residues in food commodities and pesticide poisoning. Less knowledge about biocontrolagents/natural enemies and their non-availability at right time is the key hurdles for farming communities to adopt the IPM practices on their farm. However, pesticides are still a significant component of many control programs and their negative environmental and health impacts have stimulated the research to develop alternate pest management strategies, such as biological control (BC) and other compatible, safe and sound control practices. Some remarkable early successes for both the control of insect pests and weeds (e.g. the cottony cushion scale Icerya purchase (Maskell) by the vedalia beetle Rodolia cardinalis (Mulsant) in California; the prickly pear cactus Opuntia stricta (Haw.) by the moth Catoblastis cactorum (Berg) in Australia certainly were an impetus for further research in BC field. Although the levels of success have been variable, biological control is still considered as an important means of pest control, either alone or as component of integrated management programs (Jervis, 2005; Wajnberg et al., 2007).

Introduction

Pheromones are chemicals emitted by living organisms to send messages to individuals of the same species. The class most widely explored are the sex pheromones produced by female moths which are used to attract conspecific males for mating. Bombykol, the sex pheromone of the silk moth, was first synthesized in 1959.

During the past 40 years, pheromones of hundreds of insect species have been chemically elucidated, including the sex pheromone of the codling moth. Its main component is (E, E) 8, 10-dodecadien-1-o1, a primary alcohol containing a straight chain of 12 carbons and two conjugated double bonds. Other moth pheromones are hydrocarbons, epoxides, acetates or aldehydes. These molecules all vaguely resemble fatty acids, from which they are indeed biogenetically derived.

Most pheromones consist of blends of two or more chemicals which need to be emitted at exactly the right proportions to be biologically active. The female effluvia or sex gland can contain additional compounds which are related to the pheromone components and whose biological function is often unclear. On the other hand, many attractants of male moths have been discovered simply by field screening. In several cases it could later be shown that the attractant found with this technique was identical to the natural pheromone produced by the female. In most others, the composition of the true pheromone is still unknown.

Introduction

The development of insecticide resistant populations of insect-pests, evidence of resistance, resurgence and environmental concerns have led to increased research for the alternative strategies to pesticides for control of damaging pest populations. Classical biological control and the success in that area are important and provide background and encouragement for increased efforts in the manipulation of natural enemies. Methods for manipulation of natural enemies for the purpose of reducing herbivore populations and alleviating plant stress include conservation and augmentation, habitat management and genetic manipulation.

Virtually all pest populations are affected by natural enemies to some extent. In many cases, natural enemies are the primary regulating force of the pest populations. Natural controls include effects of natural enemies (predators, parasites, pathogens), other biotic (living) factors such as food availability and competition, and abiotic (non-living) factors such as weather and soil. In pest management, biological control usually refers to the action of parasites, predators or pathogens on a pest population which reduces its numbers below a level causing economic injury. Herbivorous insects and pathogens that attack pest weeds are also considered biocontrol agents. Biological control is a part of natural control and can apply to any type of organism, pest or not, and regardless of whether the biocontrol agent occurs naturally, is introduced by humans, or manipulated in any way. Biological control differs from chemical, cultural, and mechanical controls in that it requires maintenance of some level of food supply (e.g., pest) in order for the bio-control agent to survive and flourish. Therefore, biological control alone is not a means by which to obtain pest eradication.

Introduction

Globally, India takes pride of being one of the world’s largest producers of horticultural and agricultural commodities. The rapid increase in the area under intensive cultivation of crops, introduction of high yielding varieties, lack of natural enemy load of the pests and changing climatic conditions is largely responsible for the severe pest depredations. Pest management in agriculture is a challenging task in the context of increasing agricultural productivity without upsetting the ecological balance and deteriorating the environment. Use of agrochemicals in agriculture though played a significant role to boost the agricultural production is posing enormous problems like environmental pollution, pest resistance, pest resurgence, toxicity hazards, secondary pest outbreaks, residues in feeds, foods, soil and water, destruction of biodiversity of useful natural enemies and some social economic and political problems. In response, there has been increased demand for alternative and selective pest control agents. Biopesticides are advantageous due to their target specificity, eco-safety, no development of resistance, reduced number of applications, yield and quality improvement, higher acceptability and value of produce for exports and suitability for rural areas.

Introduction

Indian agriculture accounts for nearly 65% of the country’s employment, 23% of the total GDP and nearly 20% of total export earning and supplier of raw material to major industries. Agriculture is not only the backbone of Indian economy and food security but also a way of life, a tradition and anchor of overall livelihood opportunity for about 700 million of our one billion populations. Agriculture, therefore, is and will continue to be central to all strategies for planned socio-economic development of the country.

Losses due to insect pests represent one of the single largest constraints to crop productivity estimated at 14% of the total agricultural production. Besides, insects also serve as vectors of plant pathogens. The annual global cost of pest management through insecticides is more than US$10 billion per annum. However, over-reliance of insecticides creates agricultural, environmental and pest management problems, such as frequent evolution of insect resistance, destabilization of multitrophic interactions and environmental contamination. Broad spectrum insecticides often compound these problems. Insecticides often interfere with biological control, causing secondary pest outbreaks or catastrophic resurgence of insecticide resistant herbivores. The vicious cycle of pesticide treadmill effect is observed when more pesticides lead to insects developing resistance, which in turn necessitates use of more and newer pesticides. Therefore, now it is imperative to develop a holistic system of tackling pests to make it more eco-friendly, economically viable and socially acceptable for the farmers.

Proteinase inhibitors (PIs) are small proteins that are quite common in nature. They are natural, defense-related proteins often present in seeds and induced in certain plant tissues by herbivory or wounding (Koiwa et al., 1997). PIs are present in multiple forms in numerous tissues of animals and plants as well as in microorganisms. In plants they can be counted among the defensive mechanisms displayed against phytophagous insects and microorganisms. The defensive capacities of plant PIs rely on inhibition of proteases present in insect guts or secreted by microorganisms, causing a reduction in the availability of amino acids necessary for their growth and development. PIs are of common occurrence in the plant kingdom. Plant PIs (PPIs) are generally small proteins that have mainly been described as occurring in storage tissues, such as tubers and seeds, but they have also been found in the aerial parts of plants (De Leo et al., 2002). One of the important defense strategies that are found in plants to combat predators involve PIs which are in particular effective against phytophagous insects and microorganisms. The defensive capabilities of PPIs rely on inhibition of proteases present in insect guts or secreted by microorganisms, causing a reduction in the availability of amino acids necessary for their growth and development (Lawrence and Koundal, 2002).

In the national and International scenario weeds continue to cause major problems in agriculture thereby, reducing yield and quality of crops by competing for the water, nutrients and sunlight essential for vigorous crop growth. Holm et al. (1997) listed about 200 weed species that cause 95% of weed problems for humans. As international travel and global trade increased, more plant species with potentially weedy traits are being moved around the world, giving rise to new, invasive weed problems, particularly in non-agricultural or natural ecosystems (Mack et al., 2000). The importance of weeds is reflected by the rapid growth of the use of chemical herbicides in agriculture throughout the world. The effectiveness of herbicides has dramatically increased yields in many cases and, in turn, stimulated development of new chemical herbicides. However, despite massive efforts, weeds continue to cause significant losses. These losses result from the selection and emergence of species that are not controlled by currently available herbicides, the inability of an herbicide to selectively control certain weedy species without injury to crop species, or the development of resistant strains. Among different management practices plant pathogens have also been suggested as one of several possible means of controlling the weeds that remain problematic or even as an alternative to chemical herbicides. Plant pathogens can be used to control weeds in a similar way to chemical herbicides. The term bio herbicide is coined to refer to herbicides based on any living organism (e.g. fungi, bacteria, viruses, protozoans). When the active ingredient used is a fungus, the product is called a mycoherbicide. Mycoherbicides can be applied in many ways, e.g. as aerial sprays, through ‘cut and paste’ application or in a powder form to be applied to the soil.

Plant viruses are ultramicroscopic particles that multiply only within living cells and are potentially pathogenic while composed of nucleic acids surrounded by protein coat.

More than half of the known viruses cause diseases of plants. All plant species are probably susceptible to one or more plant viruses. Symptoms of virus infection may include stunting, yellowing, necrosis, mosaic, mottling, ring spots, or abnormal structures. Economic damage consists of reduced yield and quality.

Viruses neither divide nor produce any kind of specialized reproductive structures such as spores. Instead, they multiply by inducing host cells to form more viruses. Viruses causes disease not by consuming cells or killing them with toxins, but by utilizing cellular substances during multiplication, taking up spaces in cells, and disrupting cellular processes. These in turn upset the cellular metabolism and lead to the development of abnormal substances and conditions injurious to the functions and life of the cells or the organism. The property of transmissibility is an essential criterion for viruses. Plant viruses are transmitted from plant to plant in a number of ways. Mode of transmission includes vegetative propagation, mechanically through sap, seeds, pollen, dodder and by insects.

Introduction

Horticulture is an intensive but profitable venture with higher output in terms of yield and income per unit area and time. In order to maximize the output, there has been liberal use of inorganic products like fertilizers, pesticides (insectides, fungicides, nematicides, weedicides) and other chemicals. With the continuous application of these chemicals since the last green revolution, the soil and its fertility is showing the sign of fatigue and plants developing resistance to insects, pests and diseases is breaking down and causing overall pollution to soil and water. There is growing evidence of sterility in humans and various other animals, particularly in males, related to the presence of various chemicals and pesticides in the environment. Hence the demand of the hour is looking for some alternative arrangements which are eco-friendly and moreover safe guarding the quality of the produce, which is essential so far as ornamentals are concerned. This is especially true for cut flowers and potted plants. Visible symptoms of insects, pests and diseases, have a major impact on quality. Direct and indirect effects of infections include reduction in growth, reduction in vigor, costs of attempting to maintain crop health, reduction in quality and/or market value (Hadidi et al., 1998). This may cause serious economic losses. In addition, infected plant material may not be acceptable for export.

Fungi include a large group of organisms and there are about 72,000 described species and the total number of species in the world may be as high as 1.5 million (Hawksworth et al., 1995). The infections that these fungi cause on a group of organisms viz. plants, animals, insects etc. may or may not be beneficial depending upon the type of host infected. With reference to insects, fungal infections in pest insects are beneficial which can be used effectively in biocontrol programmes. On the other hand, fungal infections in beneficial insects are harmful.

The entomopathogenic or entomogenous fungi mainly include those genera of fungi that associate with insects and some arthropods in a variety of ways. The association with the insects may be saprophytic, commensalistic, parasitic or pathogenic with the insect host. Some entomopathogenic fungi like Coelomomyces are obligate pathogens which can’t be cultured outside a living host, but most of them are however, facultative pathogens capable of growing without host insect. More than 750 spp of fungi, mostly deuteromyctes and entomophthorales from about 100 genera are pathogenic on insects and many of them offer great potential for pest management. The entomopathogenic fungi which have been most intensively investigated include Beauveria, Metarrhizum, Paecilomyces, Entomophthora, Verticillium, Hirsutella, Eryina, Mefarrhizium etc. Out of them Beauveria and Mefarrhizium have been extensively used in large scale for the control of several crop pests.

Introduction

Worldwide damage due to insect pest attack accounts for 15 per cent crop losses, despite the use of insecticides which represents over US $100 billion (Krattiger, 1997). The annual cost of insect control itself amounts to US $8 billion, thus warranting immediate and economical control measures. The crop varieties developed in the past 30 years were high yielders, but unfortunately had poor storage characteristics and were highly susceptible to pest damage. Insect-pests are capable of evolving to biotypes that can adapt to new situations, for instance they overcome the effect of toxic materials or bypass natural or artificial plant resistance, which further confounds the problem (Roush and McKenzie, 1987). Under these circumstances, provision of food to the rapidly expanding population has always been a challenge facing mankind. This problem is more acute in the tropics and sub-tropics, where the climate provides a highly conducive environment for a wide range of insects and necessitates massive efforts to suppress the population densities of different pests in order to achieve an adequate supply of food. In developing countries, the problem of competition from insect-pests is further complicated with a rapid annual increase in human population (2.5-3.0 percentage) against a meager 1.0 per cent increase in food production. In order to feed the ever expanding population, crop protection plays a vital and integral role in the present day agricultural production to minimize yield losses. Currently, the crop protection practice in agricultural systems relies exclusively on the use of agrochemicals, although a few specific cases do exist, where inherent varietal resistance and biological control have been successfully employed. The exclusive use of chemical pesticides not only results in rapid build-up of resistance to such compounds, but their non-selectivity affects the balance between pests and natural predators, and is generally in favour of pests (Metcalf, 1986).

Introduction

Biotechnology, in the recent years, has created unprecedented opportunities not only for the manipulation of biological systems for the benefit of mankind, but also to understand studies for better understanding of the fundamental life processes. Consequently, it has become the fastest and most rapidly growing technology in the world. As per US National Science Foundation, “Biotechnology is defined as any technique that uses living organisms or parts of organisms to make or modify products, to improve plants, amend animals or to develop microorganisms for specific uses”. Biotechnology offers new strategies that can be used to develop transgenic crop plants with improved growth, yield and quality and tolerance to biotic and abiotic stresses. By transgenic crop, we mean any plant containing a gene(s) which have been artificially inserted instead of the plant acquiring them through pollination. A plant in which a foreign gene has been transferred through genetic engineering is called transgenic plant and the gene so transferred is called transgenic. The inserted gene sequence known as transgene may come from another unrelated plant or from completely different species. Plants containing transgene are often called genetically modified or GM crops. Transgenic technologies have opened up many exciting possibilities to improve products with added value having application in food, agriculture, animal husbandry, environment, medicine and industry. It also offers uncommon opportunities for improvement in genetic potential of plants and animals by introduction or removal of gene(s) that regulate a specific trait.

Introduction

Vegetables are preferable host to many insects because of their succulence and suitable nutritional status. All vegetables are attacked but degree of damage and number of pests varies depending upon the crop, variety and climate. Pest infestation in vegetables has been the main bottleneck in their economical production. The problem has more socio-economic dimensions because of rapid expansion of area under vegetables, intensive cultivation, round the year cultivation, export enhancement and health consciousness among the people.

The diamondback moth (DBM), Plutella xylostella (L.), is a major pest of brassica crops worldwide. DBM has been estimated globally to cost US$ 1 billion in direct losses and control costs. (Grzywacz et al., 2010)

Introduction

Within the very small portion of the plant kingdom that includes the world’s crop plants, the legumes are a large group second to the cereals as sources of human food. Legumes belong to the family leguminosae with a group of bacteria, Rhizobium, which is able to utilize atmospheric nitrogen. This symbiosis which occurs in the root hairs may be the key to the success of legumes worldwide distribution. The family leguminosae includes about 18,000 species, characterized by their fruits, which are pods, by their (usually) alternate, pinnate or trifoliate leaves (Cobley and Steele, 1976). The diversity in the family ranges from hardwood trees of the tropical rain forests to the herbs of temperate pastures.

In practical agriculture, resistance represents the ability of a certain variety to produce larger crop of good quality than an ordinary variety at the same level of insect population. During the 19^th Century, the French wine industry survived a major set-back largely due to the use of resistant root stocks imported from America and which still maintain their resistance levels against the beetle pest (Painter, 1951). Another important example of resistant variety is the U-4 variety of cotton possessing high level of resistance to the jassid, Emposasca spp. (Parnell, 1925). The excessive use of pesticide on oilseed crops needs to be minimized owing to several reasons: (i) most of the pesticides are lipophilic and are likely to be carried in the oil (ii) in a few cases like Brassica, leaves and inflorescence are consumed as saag (pot herb), (iii) the oilseed crops provide the raw material for the vanaspati industry, cosmetics, etc., (iv) many of the oilseeds and oils are directly consumed without further processing, and (v) the oil cakes are used as cattle feed. Thus there is an urgent need to exploit the non-pesticidal methods of pest control, among which the use of resistant varieties assumes a great significance. The details of each oilseed crops are given below: