eChapters

Rabbits are produced for meat, wool and research and as pets or for a hobby. Meat production is the most important commercial aspect of rabbitry. The domestic rabbit is primarily herbivorous and will consume most types of grains, oil seed cakes, brans, greens and hay. Diets provided, whether home grown or commercially prepared, consist almost entirely of ingredients from plant sources. Although, the producers / farmers mostly rely on home grown feeds, a good portion of the rabbit feed presently used is commercial pelleted feed. Since the rabbit can utilize a certain amount of forage, it has a place in food production by making use of some non-competitive feeds.

Definitions

Pen Enclosure for housing rabbits that allows for freedom of movement by rabbits and allows for the provision of a variety of environmental enrichment strategies. Cage Fully enclosed container for housing rabbits which, because of its size, restricts freedom of movement by rabbits and limits the provision of environmental enrichment strategies. Cages are usually constructed from metal or plastic, with solid or mesh sides.

A suitable site for housing is very important. It is better to select a site which has good drainage, adequate shade like under trees, and with sufficient surrounding space from strong winds. Basically the shelter must protect rabbits from extreme temperatures and predators like snakes, mongoose, dogs and other animals.

Rabbits can be raised inside the building also or outside in hutches with a protective roof. A hutch is a small building containing cages for housing a few rabbits (6 to 12) a back-yard scale. They are generally made of wood or stone one and chicken wire mesh. The floor may be made of a stronger ranger mesh or soil floor bedded with straw. Hutches can also be constructed with local building materials such as tree and woven split bamboo, etc.

Introduction: Most young rabbits will be used for meat and skins; some will be kept for breeding. Whatever they are used for, the rabbit keeper will benefit if they are well cared for.

Handling of Rabbits: There will be times in any rabbitry when the animals will have to be picked up, e.g. when a doe is moved to a breeding hutch or when young rabbits are weaned.

When it is necessary to pick up a rabbit for any purpose, the aim should be to cause it no discomfort and to prevent it struggling. So it must be handled gently but firmly. There are three ways to hold a rabbit according to its size. 

Breeds of Rabbit

There are many breeds of domestic rabbits in the world and all have different qualities. Out of the number of breeds and varieties about 38 breeds and 87 varieties are recognized and well established world wide.

For commercial purposes, the most important differences between rabbits are their size, colour breeding ability and suitability to the climate. Examples of several different breeds of rabbits are given below. Some of these might be used for improving local rabbit herds.

Brief History

Fondness of man for rabbits is well established by its appearance in the Aesop’s fables and Vishnu Sharma’s ‘Panchtantra, both of which date back to 2nd century B.C. However, domestic rabbits are descendents of wild species of Western Europe and North Western Africa where Oryctolagus still exists. Interestingly, it was the Romans who first raised rabbits in leporaria (enclosed warrens) as a game animal. Like Spaniards, Romans also ate fetuses of newborn young ones whom they called laurices. These leporaria ultimately paved the way for development of game parks in the Middle Ages. The monks ate laurices during Lent because they were an aquatic dish.

Rabbit domestication dates back no farther than the previous millennium. It were the Phoenicians who are said to have discovered the wild rabbit Oryctolagus cuniculus of Southern Europe and North Africa when they reached the shores of Spain about 1000 B.C. In Roman times, the rabbit was still emblematic of Spain. The Roman spread the rabbit throughout the empire as a game animal. Like the Spaniards, the Romans also ate foetuses or new born rabbits, which they called laurices. It then becomes a practice that the rabbits were kept in leporarian, stone –walled pens or parks for hunting purposes. These leporaria ultimately paved the way for the development of game parks in the middle Ages. The monks ate laurices during lent because they were an aquatic dish. In France, only the lord of the manor could maintain a warren.

Preference of herbicides for weed management in Agriculture and Horticulture

Weeds are unwanted and undesirable plants which interfere with the utilization of land and water resources and pollute atmosphere with their allergic pollen thus affecting human welfare adversely.  They are the plants out of place, growing where we want other plants or no plants at all.  They compete with desirable and beneficial vegetation reducing the yield and quality of the produce.  The effect of weeds in agriculture or horticulture is greatest.  There is a scanty reliable study of worldwide damage to crop yields due to weeds.  Whether the data are available or not, it is well known that losses caused by weeds exceed the losses from any category of agricultural pest, viz., insects, nematodes, diseases, rodents etc. Weeds account for 45% while insects 30%, diseases 20% and other pests 5% of the total annual loss of agricultural produce186.

Introduction

India has a big challenge in fruit production in the current backdrop of decreasing per capita land holding and static fruit productivity. In recent years, China has surpassed and secured top position in the fruit production in the world accounting for 4,44,651 mt production followed by India and Brazil.  Now Chinese share in the fruit production is around 13 per cent while India contributes 10.2 per cent, Brazil 8 per cent and USA 6 per cent of total fruit production.

India is bestowed with a wide variety of agro-climatic conditions and enjoys an enviable position in the horticultural map of the world. Almost all types of fruit crops (tropical, sub-tropical and temperate) are grown in one or other part in the country.  The major tropical and sub-tropical fruits grown in India include mango, banana, papaya, orange, mosambi, guava, grape, pineapple, coconut, sapota, ber, pomegranate, litchi, aonla, bael, jackfruit etc.  Cashew nut cultivation has a big potential and its production, productivity and export has increased significantly in recent decades. Indian grape has recorded highest productivity per unit area in the world. The productivity of fruit per unit area in India has increased nearly from 10 t/ha to 12 t/ha in almost one decade.  However, the average productivity in most of the fruit crops is far below than satisfactory except grape and banana in few states.  It is paradox to record that India’s contribution in the overseas market is almost (0.11 per cent) negligible (Chadha, 2000). However, other countries like Mexico, Philippines and Venezuela, which produce far less, export 4 per cent of their total production.

Introduction

To keep pace with the ever-increasing demand for crop yield by the exploding population, use of chemical fertilizers and pesticides in agricultural production has become indispensable.  Production cost of agriculture has skyrocketed owing to the abandoning of green, organic farmyard manure and use of chemicals. However, the problems associated with chemical pesticides are abundant. The excessive application of chemical fertilizers causes soil sealing, fertility diminishing and residual problems. The leftover chemical fertilizers and pesticides have seriously affected the quality of agricultural products, people’s health and caused environmental pollution.  The over use of fertilizers has also damaged the soil’s original micro-ecological balance and deteriorated the diseases spread by soil.  While some pesticides must be abandoned because of their unacceptable non-target effect, there will always be a need in agriculture for safe and selective chemicals to limit the effects of pests.  More significantly, it is becoming increasingly more difficult and expensive to find new kinds of synthetic chemical pesticides.  Implications of chemical pesticides in ecological, environmental and human health problems have increased public awareness and concern regarding the continued use of agrichemicals that are damaging to human or  environmental health thereby obviating the search for effective alternative approaches which have minimal deleterious effects, more environmentally friendly, and will contribute to the goal of sustainability in agriculture.  In this line Plant growth-promoting rhizobacteria (PGPR) present immense potential and promise as effective substitutes for chemicals.  PGPR enhance plant growth and survival, control soil-borne fungi, and induces systemic resistance to phytopathogens and is used as inoculants for biofertilization, phytostimulation and biocontrol.

Introduction

After water, nitrogen is the most critical nutritive element for crop productivity and human efforts to produce food and energy have greatly changed the nitrogen cycle of the earth. Sustainable cropping systems throughout history and across the world have relied on the combination of a cereal with an N-fixing legume. In recent history, cereals have dominated global agriculture, while legume areas and productivity have stagnated or even declined. An atmosphere around us contains nearly 78% nitrogen, which is in free form. Hence it is not available to plants. At present, India produces around 206 million metric tones of foodgrains for its growing population, increased foodgrain cannot be produced unless we carefully make use of biological nitrogen. Biological nitrogen fixation is the key to sustain agricultural productivity through the application of biofertilizers in the field. However, there is an urgent need to transfer this technology on the field to farmers and industry by producing these fertilizers on large scale.

INTRODUCTION

One of the most dangerous ecological crises being faced by all living organism now-a-days is the pollution of the environment. It is easier to describe pollution rather than to define it. It is presumed that the environment in past was more or less pure. But due to various activities of man such as industrialization, urbanization, agricultural practices etc, composition of the environment gets changed which is called environmental pollution. Any substance that creates pollution is called ‘pollutant’. There are different types of pollution among which pollution caused by toxic level of heavy metal pollutants is called heavy metal pollution.

Heavy metal pollution is a problematic field of research and is gaining immense importance now-a-days. We have 104 elements in the periodic classification of which 80 are metals. According to Passow et al. (1961), heavy metals are those having densities more than five (5 g cc^-1) and atomic weight twenty three. The term ‘heavy metal’ is imprecise but is widely used although others such as ‘toxic metal’, ‘trace element’ are possible alternatives. Sources of these heavy metals are varying; some of these are encountered in water, air effluent, solid waste and sewage. They are emitted out from various sources e.g. waste water from electroplating industry (Cr, Ni), air emission from fluorescent lamps (Cd, Be), paint pigment waste (Pb, Cr), auto-exhaust emissions (Pb, Te) etc.

INTRODUCTION

The purpose of writing this chapter is to develop a comprehensive understanding of the role of functions of water in plant growth and development. Water is essential to life on earth as the living organisms contain 80-90 per cent water. A typical crop or grassland will transpire approximately 500 ml of water per 10 g of dry matter produced. Water has a tremendous effect on the environment near the earth, which on regional basis we call ‘climate’. Ecological importance of water is due to its physiological importance because water affects the plant growth through physiological processes. All metabolic activities in the plant cell or tissue depend on water status of the plant. For example, in a maturing seed, respiration rate is highest as it moves towards maturation stage, water content decreases and hence rate of respiration slow down. At the harvesting stage, when the water content is 10-20%, the respiration rates become negligible. Now in a stored seed if the water content will be high it will result into higher respiration, thus release energy, which will increase the temperature and will finally destroy the seed.

INTRODUCTION

Among plant nutrients, our soils are particularly low in nitrogen and therefore, require is high doses of nitrogenous fertilizers for getting optimum productivity. Added to this is the problem of poor efficiency of nitrogeneous fertilizers which under normal conditions is only 40 – 50 %, still less for rice ranging from 25 – 35 %, and the residual effect for the succeeding crops is never more than 10 %. The rest of the applied nitrogen is lost either through volatilization, leaching or denitrification (Kashyap, 1978). The high cost of nitrogenous fertilizers and their poor utilization efficiency very much add to the high cost of cultivation. Hence, the need of the hour is to decrease our dependence on chemical fertilizers and increase the efficiency of the fertilizer thus used. The increase in nitrogen efficiency in crop plants can be achieved by reducing denitrification with the use of nitrification inhibitors, reducing the soil compaction, improving drainage conditions, use of soil improving crops, and adopting carefully the irrigation procedures (Carlson, 1980). No doubt exploration of this possibility is a big task, nevertheless, the understanding of physiology and biochemistry of nitrogen nutrition at molecular level is obligatory and is likely to add insight to achieve the hard task goal.

INTRODUCTION

The metabolism of carbohydrates is vital for plant growth and development, and to the yield of major plant products such as starch and sucrose. Starch, sucrose and fructose are the three important carbohydrates which are utilized in most of the higher plants. The majority of sucrose that is synthesized in higher plants during photosynthesis is exported to non-photosynthetic cells (ap Rees, 1992). Starch serves as an important storage for carbohydrate residues. The degradation (breakdown) of starch ensures retaining of important life processes in plants when there is carbon shortage, for instance, during night period in leaves or in resting organs such as potato tubers.

Phospholipids are the most abundant lipids of biological membranes. They serve primarily as structural components of membranes and are never stored in large amounts. As the name of phospholipid implies, this group of lipids contains phosphorus in the form of phosphoric acid groups. The major phospholipids found in membranes are the phosphoglycerides (phosphatides) (Fig.1). Which have two fatty acid molecules esterified

INTRODUCTION

Iron in the terrain’s crust is more oxidized now than it was when life evolved. It has been hypothesized that dissolved ferrous iron could have been a convenient oxygen acceptor and that deposition of oxidized iron in sediments must have taken place before oxygen could have entered the atmosphere in significant quantities. Obviously, during early evolution on this planet, the essential elements are present only in reduced form. Today a number of elements are present only in a highly oxidized form and considerable energy must be expanded to reduce them to a form similar to that on early earth which plants can utilize.

Iron represents essential elements which are usually available in oxidized form but must be reduced, often using metabolic energy, before they can be utilized. For the first time, Gris (1844) observed yellowing of grapevine leaves in absence of iron in the nutrient solution in which these plants were growing. Later, iron was reported to be essential for diverse group of plants. Due to a great variation in iron requirement by different plant species, it is difficult to decide whether iron is a macro or micronutrient.

Introduction

Salinity is a significant environmental stress for crop plants it account for about 70% of the losses in the crop yield. It adversely affects seed germination, seedling growth and different metabolic activities in plants (Begum et al. 1997). It reduces DNA, RNA and protein synthesis and differentially influences the activities of the hydrolytic enzymes (Kumar et al. 1996).

Plants are classified as glycophytes or halophytes according to their capacity to grow on high salt medium. Most crop plants are glycophytes and cannot tolerate salt stress. High salt concentration decreases the osmotic potential of soil solution creating a water stress in plants. Secondly they cause severe ion toxicity since Na+ is not readily sequestered into vacuoles as in halophytes.

The widespread nature of saline soils compounded by the geographical distribution of man’s population and agricultural practices are largely succeeded in increasing salinization in arid and semi-arid lands. Most of the crops are sensitive to even low concentration of NaCl.

Introduction

Chickpea, the world’s third most important food legume, is currently grown on about 10 m ha worldwide, with 95% cultivation in the developing countries. India is the largest producer of chickpea in the world. Chickpea is grown under rainfed conditions in winter in India subjecting it to abiotic stresses. Consequently it experiences water deficit stress at one or the other growth stage(s) which affects the crop productivity.  Among the abiotic stresses to which chickpea is subjected to drought stands to be the number one problem in major chickpea growing regions because the crop is grown on residual moisture and the crop is eventually exposed to terminal drought (Johansen et al., 1994). A distinctive variation exists between the plant in sensitivity to water stress. Chickpea is considered relatively more tolerant, possibly because of its deeper root system is and its smaller leaves and canopy. Several adaptive mechanisms are evoked by plants in response to water stress (Chaves et al., 2003). These traits enable chickpea to ensure its survival in different environmental conditions.

Introduction

It is an established fact that water in terms of direct deficit (drought) as well as water surfeits (flooding and water logging) and poor irrigation water quality (salinity)- are major constraints on the use of solar energy for food, feed and fiber production in almost all the agricultural regions of the world. The various biophysical, physiological, genetic, agronomic and ecological aspects of plant water relations have been thoroughly reviewed in recent years with the objective aimed at water availability as a constraint on crop production. This review will attempt a limited synthesis of these aspects, drawing mainly from research on drought resistance in grain crops, rice in particular, and emphasizing the progress- theoretical and practical- that could result from collaboration between physiologists, geneticists and plant breeders. A central theme will be research and development aimed at fitting crop plants to fluctuating drought prone environments. It is noteworthy that shortage of water restricts crop productivity all over the world-not just in those areas classified as arid or semiarid, but in any area in which the evaporative demand exceeds rainfall during the growing season. As such, the interaction between genotype and environment in situations has an important bearing affecting the physiology and also biochemistry at cellular level vis-à-vis the crop phenology. Cultivars with better ability to access soil water and improved water use efficiency could increase yields in an economic and environmentally sustainable way.

Introduction

The study of abiotic stresses in plants has advanced significantly in recent years. However, the majority of experiments testing the response of plants to changes in environmental conditions have focused on a single stress treatment applied to plants under controlled conditions. In contrast, in the field, a number of different stresses can occur simultaneously. These may include conditions such as high irradiance, low water availability, extreme temperature, or high salinity and may alter plant metabolism in a novel manner that may be different from that caused by each of the different stresses applied individually. The response of plants to abiotic stresses in the field may therefore be very different from that tested in the laboratory (Cushman and Bohnert, 2000).

Introduction

The phytohormone abascisic acid (ABA) was discovered in connection to studies related to shedding of fruits and leaves, also called abscission, and the dormancy of buds. It was first identified and characterized by Frederick Addicott and his associates in 1963 while studying the compounds responsible for the abscission of cotton fruits. Inhibition of growth and maintenance of the dormancy of buds are the most important visible effects of ABA. The concentration of ABA does not remain constant as its concentration decreases in the buds significantly after sprouting and rises during seed and fruit production. Its concentration in dormant seeds is very high and considered as an efficient inhibitor of germination. The role ABA plays during the abscission of fruits and leaves is not clearly understood as its effect is very clear in case of fruit abscission where as it is not very clear on the abscission of leaves. However, the regulatory effect of ABA on the water balance is established in plants. It also induces stomatal closure to inhibit further loss of water. Being a growth inhibitor, ABA also reverses the effect of growth-stimulating hormones like auxin, gibberellins and cytokinin in different tissues of a plant. One of the main goals of phytohormonal ecology is to study the interactions between biotic and abiotic stress at hierarchical levels of biological organization.

Introduction

There are a number of chemicals in the environment, some natural other man-made, some toxic other non-toxic. These are toxic chemicals, whether natural or man-made, which has created problems for the environment and biota on the earth. Of these toxic chemicals, heavy metals are extremely hazardous. Metals are present naturally in the earth’s crust at various levels. However, increasingly widespread heavy metal pollution resulting from anthropogenic activities has caused serious environmental problems and is posing threat to both wild life and human population (Nriagu and Pacyna, 1988). Natural sources include weathering of mineral and metal ions from rocks, displacement of certain contaminants from groundwater or subsurface layers of soil, atmospheric deposition from volcanic activity, and transport of dust. The anthropogenic sources include deposition of industrial effluents, application of sewage sludge, deposition of air-borne industrial wastes, military operations, mining, landfill operations, use of agricultural chemicals, gas exhausts and energy and fuel production (McIntyre, 2003).

Introduction

The term ‘lectin’ was coined by William C. Boyd in 1954 for their property of selectivity (Latin ‘legere’, to pick up or choose). In 1888 H. Stillmark of Russia gave the first description of what we now know as lectin. While investigating the toxic effects on blood of extracts of the castor bean (Ricinus communis), Stillmark observed that the red blood cells were being agglutinated by a protein and gave it the name ‘ricin’. Shortly afterward ‘arbin’ was extracted from Arbus precatorius. Because they were first isolated from plants, lectins came to be known as phytohaemaglutinin. Now it has become clear that lectins are present not only in plants but also in some bacteria, vertebrates and invertebrates. However, lectins are most widely distributed in plants, reported in almost 1000 plant species.

Plant lectins are a very heterogeneous group of proteins; as far as their occurrence within the plant kingdom and distribution over tissues are concerned. They show high degree of heterogeneity with respect to biochemical and physiological roles, because of their widely different carbohydrate binding specificities (Etzler 1986; Rüdiger 1988; Goldstein and Hayes, 1978). Besides the fact that they all exhibit carbohydrate binding activity, most of the plant lectins behave as typical storage proteins (Peumans and Van Damme, 1995 b).

Introduction

Phenolic compounds have been shown to be of importance in regulation of plant growth, development and metabolism, therefore now they are not considered as passive by products of any catabolic or anabolic processes. Salicylic acid is one of them and it is a naturally occurring phenolic which has received much attention due to its association with economically important plant responses to disease and other stresses (Raskin, 1992; Borsani et al., 2001; Clarke et al., 2004). Centuries before medical scientists had identified numerous therapeutic effects of salicylates. Leaves and barks of willow tree were used by women as a pain reliever during child birth in 4th century B.C. It also cured aches and fevers. Due to a number of curative properties of willow bark, in 1828 Jahann Buchner, a scientist from Munich had isolated a small amount of silicin - a salicylic alcohol glucoside, the major salicylate in willow bark. In 1838, Rafaela Piria had given the name salicylic acid (SA), from the Latin salix, a willow tree. Further during 19th century SA and other salicylates, mainly methyl esters and glucosides easily convert to SA, isolated from a number of plants. Salicylic acid has an aromatic ring which bears a hydroxyl group or its functional derivative (Fig. 1).

Introduction

The respiratory electron transport pathway of plant mitochondria comprises the cytochrome (Cyt) pathway and alternative pathway (McDonald et al., 2002). Both the cyt and the alternative respiratory pathways start at protein complex I when NADH is being oxidized. One H+ (proton) is transported by the complex I to inner membrane space, whereas two electrons are transported within the inner membrane by the ubiquinone, which at its reduced state (Qr) transfers these electrons either to complex III or to the Alternative oxidase (AOX). Ubiquinone is the point in which reactions can proceed in different ways, and it is called the branch point. Cyt respiratory pathway is present in all living organisms. It proceeds while complex III pulls out a proton from the mitochondrial matrix to the inter membrane space. The electrons are received by cytochrome c which spreads up to the outer side of the inner membrane towards protein complex IV, which then pulls out another proton similar to complexes I and III, and transports the electrons back to inner domain of the mitochondria. As a result, oxygen is consumed with a proton and the two electrons to produce water (Fig 1).

Introduction

Seed, the basic input of crop production technology, is exposed to various stress factors right from its formation to the completion of its germination. Even after germination, the stressed seeds may fail to emerge into a healthy plant and thus, the subsequent seed formation is also affected both quantitatively and qualitatively.

The stress factors may be abiotic, biotic or mesobiotic. Environmental factors such as climatic parameters, nutritional deficiencies, soil factors and conditions of storage are the examples of abiotic stress factors. Insects, fungi, bacteria, nematodes and other plant parasites constitute biotic stress factors whereas viruses, viroids and virusoids and similar agencies are the examples of mesobiotics factors that bring about stress over the seed. Apart from these conspicuous causes of stress, there are certain other factors also, which may affect the influence of stress over the total performance of the seed. For example, the crop improvement efforts bring about changes in seeds quality that can have considerable effects on the vulnerability of the seed to invasion by various biotic factors.

Introduction

The life cycle of a plant passes through biotic and abiotic stresses and plants are being attacked at different stages of growth by a number of disease causing organisms. These organism including bacteria, fungi, viruses, and nematodes attacks plants. These pathogens caused large crop losses and probably since the beginning of agriculture have contributed to human hunger and malnutrition. The control of plant diseases is thus of fundamental importance and is a major objective of plant breeding and pathology programme and agriculture chemical industry. Plants resists pathogens attack both with preformed defenses such as antimicrobial secondary compounds and by inducing defense responses (Hammond and Jones, 2000, Heath, 2000). Inducible defenses can be activated upon recognition of general elicitor such as bacterial flagellin and even host cell fragments released by pathogens damage (Gomez and Boller, 2000, Hammond and Jones, 2000). However, plants also involved sophisticated recognition systems to detect proteins produced during infection by specific races of pathogens (Martin et al., 2003).

Introduction

Plants are responsive to the applied Non-scheduled caste, which constitute most of the vital macromolecules and metabolites related to its vegetative and reproductive cycle. The applied fertilizer N enhances crop productivity per unit area, as agricultural soil deficient in N worldwide. The fertilizer application is thus considered essential to meet the requirement of the burgeoning population, particularly in the developing countries (Abrol et al., 1999; Chanda and Sati, 2005). The farmers practicize heavy dressing of N-fertilizers in crop fields for high productivity, which has resulted into world including Indian sub-continent and China have resulted into the excessive use of N-fertilizers intending to maximize crop yield. Decrease in the organic fertilizer input and depletion of micronutrients in intensive cultivation zones have caused a decline or stagnation in the crop productivity, which  has been attempted with a further loading of soluble chemical fertilizers (Maleshwar, 2003; Kumar and Yadav, 2003; Anonymous, 2004; Chanda and Sati, 2005; Abdin et al., 2006).

The mites belong to the Class - ‘Arachnida’, Order - ‘Acarina’. Most of the phytopathogenic mites are classified under the two Families - Tetranychidae and Eriophyidae.

The mites belonging to the Family - Tetranychidae are generally known as Tetranychids. They are very minute, and less than 100 microns in size. The body is non-segmented and the head, thorax and abdomen are  not distinct, but rather fused together. The life cycle of a tetranychid mite consists of an egg stage, three nymphal stages viz., protonymph, deutonymph and tritonymph and an adult stage. In the protonymphal stage, which is also called the larval stage, the mites have only 3 pairs of legs. In all the other nymphal stages and the adult stage they have 4 pairs of legs. The mites are roundish or oval in shape, with biting and chewing, as well as piercing and sucking type of mouthparts (Fig.190).

All control measures are directed to bring down the nematode population low enough to raise the crop successfully and profitably. The choice of control measures to be taken depends upon the nematode species to be tackled and the crops involved.

1. Cultural methods 
The objective of these methods is to adopt suitable land management practices, so as to bring down the nematode population in the field to a low level, which may not cause economic injury to the crop or to keep the field free from parasitic nematodes by adopting suitable preventive measures. Besides causing direct damage to the crops, several nematode species are known to transmit many fungal, bacterial and viral pathogens, which aggravate the extent of damage caused to the crops. Many of these pathogens gain access to the host plants only through mechanical injury caused by the nematodes. By controlling the nematode parasites, the incidence of diseases caused by such phytopathogens can also be avoided to a large extent. Cultural methods, though may not give spectacular results within a short span of time of a single season or year, as in the case of chemical control measures, if followed over a number of years is sure to give encouraging results. Cultural methods include crop rotation, fallowing, ploughing, flooding, trap cropping, use of organic amendments, selection of seeds and seed materials, use of resistant and tolerant varieties etc.

‘Nematodes’, otherwise known as ‘eel worms’, ‘thread worms’, ‘round worms’, and ‘nemas’ are unsegmented, smooth-bodied, mostly minute, worm-like metazoan organisms. They are classified under the Phylum - Nematoda. The term ‘Nematode’ has been derived from the two Greek words ‘Nema’ = thread and ‘Eidos’ = form, which means thread-like organisms. At present, the nematodes, which are exclusively parasitic on man and livestock are studied under ‘Helminthology’ or ‘Parasitology’, while the plant parasitic or phytonematodes, as well as free-living nematodes are studied under ‘Nematology’, a branch of biological science that exclusively deals with nematodes. Cobb coined the term Nematology in about 1920.

Nematodes are ubiquitous and are found every where life can sustain. They can survive in any type of environment and are found from the arctics to the tropics and from the oceans to the top of hills. Though basically aquatic, nematodes have adopted terrestrial habits. They are mostly found in the soil around the rhizosphere of roots of plants. They constitute 80 - 90 per cent of all multicellular organisms and the number of nematodes may vary from 1.8 - 120.0 million per sq. m. of soil according to Kevan (1965). At present the number of established species is about 15,000, but there may be several thousands more.

For effective and economic control of pests, besides selection of appropriate plant protection chemicals, application of the chemicals at the most vulnerable growth stage of the pests and use of chemicals at the correct dosages, selection of proper plant protection appliances to carry out the operation is also of vital importance so as to ensure uniform application of the chemicals.
 
Plant protection chemicals are mostly used as sprays and dusts using sprayers and dusters respectively. However, in most of the cases spraying is preferred to dusting. Different types of sprayers and dusters are being used for these operations and in both, there are manually operated as well as power operated equipments and in sprayers there are both hydraulic and pneumatic types of sprayers.

The nature of the pesticide formulations to be used and the purpose for which they are used also determine the type of equipment to be used. Dusters are used for dusting insecticidal dust formulations; sprayers are used for spraying insecticidal liquid formulations; granular applicators are used to apply granular formulations; fumigators are used to apply fumigants to fumigate godowns, warehouses, rat holes etc.; soil injectors are used to inject pesticides at a particular depth of soil under pressure; flame throwers are used to throw flames at specified targets.

The chemicals, which can destroy pests or prevent their occurrence by their chemical action, are known as ‘pesticides’. Pesticides include ‘insecticides’, ‘acaricides’, ‘nematicides’, ‘rodenticides’, ‘molluscicides’ etc., which are used to destroy insect pests, mites, nematodes, rodents, slugs and snails respectively.

Pesticides have been used even before the time when man never knew how to read or write. Even before 200 BC, several substances were known to control pests. Sulfur, arsenic poisons, fluorine poisons, as well as some plant extracts and oils were used to control pests. However, these substances could destroy only a few specific pests.

Advances in the invention of pesticides

The invention of many of the present day pesticides started only after 1867. Paris green, a synthetic chemical was the first pesticide used to control the Colorado beetles of potato.  Up to  1939,  only  a few inorganic  chemical compounds and plant poisons were used as pesticides. Only after the Second World War much advances were made in chemical research. After the invention of DDT in 1939, a revolution had started in the field of pest control.  Following the introduction of DDT,  several other pesticides were identified and introduced for pest control. In 1941, BHC was invented by the British and French scientists. During the same period, organophosphorus pesticides were invented by the German scientists and parathion, malathion, demeton etc. were introduced.

Insect pest control includes all measures adopted to make the life of insects hard and ultimately to destroy them or to prevent their multiplication and spread. Such measures can be taken up before the appearance of the pests or after occurrence of the pests. To achieve this purpose, it is quite necessary to know the factors which favor the occurrence of the pests and acquire enough knowledge about the nature and life cycle of the pests, the vulnerable growth stage at which they can be effectively destroyed and appropriate measures of control. Control measures may be either preventive or direct.
Insect pest control is broadly classified under two different heads viz., natural control and applied control.

I. Natural control
    1.    Climatic conditions. Temperature, rainfall, sunshine etc.
    2.    Physical or topographic factors. Mountains, oceans, rivers, lakes, forests, deserts etc.
    3.    Natural enemies. Parasitoids, predators including insects, birds, mammals, reptiles etc.
    4.    Disease causing organisms or parasites. Entomophagous fungi, bacteria, viruses and other microorganisms.

Collection and preservation of insect specimens is the best way to study their morphology, habitat, distribution, host relationship and many other interesting features. Killing, mounting and arranging the insects in some particular sequence creates much more interest than merely studying museum specimens or looking at pictures. A collection of varied types of insects goes a long way in increasing the knowledge and understanding of the taxonomy of insects.

Not all insects are found in every season and in every place. Their presence mostly depend on the availability of the host, as well as the climatic conditions. Though many insects can be collected in any season, they  are  naturally  abundant  in  moist,  warm  weather,  especially  in the  spring and early summer. To get a good collection, insects have to be collected continuously in all the seasons of the year, from all plants and plant parts, from stored grains and food products. Several types of butterflies, moths, bees, wasps, beetles and flies can be collected from flowers, which they frequent to collect nectar. Many insects can be collected from leaves, stems, fruits, roots and such plant parts. Many insects are found in water and on water plants. Some are found in barks of trees or in decomposing organic matter. These insects have to be collected from different localities where they are found. Most of the insects are diurnal, while some of them are nocturnal. Some are attracted to light. So, a knowledge of the habits of insects is important in making a good collection. Sometimes better specimens may be obtained by collecting the immature stages and rearing them into adults wherever possible. Keeping records of pest collections may help Entomologists to forecast largescale pest occurrence.

Though many of the insect species are injurious to man, his crops and his livestock in different ways, not all the insects are injurious. Some insect species are beneficial to man in many ways.  A  few  are  productive insects and yield materials directly useful to man. Of these, the most important ones are the honeybees, which give honey and bee wax, the silkworms, which give silk and the lac insects, which give lac. Some other insects are useful to man indirectly in many ways.

productive insects

1. Honeybees (Apis species)
Order - Hymenoptera
Family - Apidae

Kinds of honeybees

There are five kinds of honeybees in India. They are :
Apis dorsata - the rock bee
Apis florea - the little bee
Apis indica - the Indian bee
Apis mellifera - the European bee
Melipona iridipennis - the dammer or stingless bee

One of the chief aspects of Entomology is the study of insects from the standpoint of their innumerable relations and activities affecting the interests of man. More than any other living organisms, insects have more intimate and complex relationship with man. It is well known that insects affect human interests both for good and bad. However, their injurious activities are of much greater concern to man than the beneficial aspects of their activities. Several insects are beneficial to man in several ways, both directly and indirectly and there are scores of other insects, which do not interfere with the interests of man in any way.

From the time man stepped into the domain of insects, a stifle has started between the insects and man. To meet his various demands for food, clothing, shelter and various other requirements, man cultivates various crops and raises many domesticated livestock. Unfortunately for man, insects also have started depending on these for their living. When the requirements for man and insects happen to be the same, a race is on for their survival and existence. Insects attack plants and livestock and cause extensive damage and economic loss. So, man considers such injurious insects as his enemy and to safeguard his interests tries to destroy them by various means. However, man’s supremacy and intelligence have not proved a match to the rapid propagation of insects and their various adaptations to withstand any hardship and adverse conditions. In the effort to gain an upper hand, it has not been possible for man to destroy the unwanted insects completely and the struggle is going on as a never-ending ordeal.

The classification of living organisms has passed through several changes and has reached the present stage with the gradual assimilation of more and more knowledge about them. The classification is mainly based on the anatomy, life style, habits, habitats, metamorphosis and such other characteristics. Though the concept of classification of living organisms was perhaps started by Aristotle between 384 - 322 BC, it was the Swedish scientist Carl Linnaeus (1758) who presented the classification, which was acceptable to most of the Taxonomists. He propounded the binomial nomenclature of naming each and every organism of animal and plant origin with a generic and species name. In his classification, he was consistent in using Latin names for all the organisms. He was the originator of a regular system of classification in which he recognized larger and smaller categories, the larger ones comprising of a varying number of smaller ones. Because of his contribution in the field of Taxonomy, he is rightly called the ‘Father of nomenclature’. A.D.Imms later modified the system to some extent in 1961. However, Brauer (1885) laid the foundation of the modern system of classification of insects. He was the first one to emphasize the fundamental division into primitive wingless insects, the ‘Apterygota’ and the winged or secondarily wingless insects, the ‘Pterygota’. The latest code on classification and nomenclature was approved and published by the ‘International Trust for Zoological Nomenclature’, London in 1964.

Protection from natural enemies and adverse environmental and climatic conditions is vital to safeguard insects and to this effect, insects possess a great variety of protective structures and mechanisms without which they cannot survive.

    i)    Food. Each insect species has certain nutritional requirements for the completion of life cycle. If the required food for any particular species gets reduced in a particular locality, that species will gradually disappear from that locality, though other environmental conditions may be favorable. Under normal conditions, there may be sufficient food for the insect to live on and continue its race. In the event of sudden increase in the population of an insect, the density of the population becomes too high to be supported by the food available in the area. Under such conditions, some individuals of the species either migrate to other suitable areas where enough food is available or else starve, if the species has limited power  of  dispersal  as  in  the  case  of  many  coccids.  According  to  the nutritional requirements insects are characterized as ‘omnivorous’ (feeding on different kinds of both plant and animal food), ‘carnivorous’ (feeding on animal food) and ‘herbivorous’ or ‘phytophagous’ (feeding on living plants). Those insects, which feed on many cultivated and wild species of plants, are termed ‘polyphagous’ (e-g) Locusts, grasshoppers, cutworms etc. If the feeding activities of a particular species of insect are confined only to plants of one botanical family, it is termed ‘oligophagous’ (e-g) cabbage butterfly - Pieris brassicae. When only a single species of plants constitute the food of a particular species of insect, it is termed ‘monophagous’ (e-g) Brinjal fruit borer.

Insects generally reproduce by laying eggs or ‘ova’. The initiation of growth inside an egg, which in most cases is preceded by fertilization, leads to a long series of changes, finally attaining the adult stage and in due course to sexual maturity and finally to reproduction of a new generation. This chain of events from the egg stage to death constitutes the ‘life history’ or ‘life cycle’ of an insect.

Eggs are laid singly or in batches of only a few or up to hundreds or  even thousands. Generally eggs are laid under conditions, where food is available for the feeding of the future young ones.  The eggs are generally smooth, elliptical or oval, but some have diverse shapes such as, disc-like, hemispherical, conical, globular, spindle and many other forms. The egg surface may also have a variety of textures. In some aquatic insects, the eggs are covered with a gelatinous secretion, which swells in water forming a jelly-like spawn. In mosquitoes, the lateral sides of the eggs are expanded, which serve as floats. Eggs vary in size, from microscopic to about 3.0 mm. in diameter and 5.0 - 6.0 mm. or even more in length.

The development of an insect is a continuous process, but on the basis of external manifestations, it is divided into definite stages. The stage within the egg is termed ‘embryonic development’, that after hatching ‘post-embryonic development’ and the changes of form during the post-embryonic development constitute ‘metamorphosis’.

Similar to animals of the higher order, insects also possess all important internal systems of organs necessary for the proper performance of the various vital functions. The most important of the systems are the alimentary or  digestive  system,  the  circulatory  system,  the  respiratory system, the reproductive system and the excretory system. The fundamental arrangement of the various organs is more or less similar in all insects and does not exhibit much remarkable variations as seen in the external morphological features. The dorsal blood vessel or heart runs along the median line immediately below the dorsal wall. The digestive system including the alimentary canal and its appendages lie in the middle, below the heart. The nervous chain lies below the alimentary canal and immediately  above  the  ventral  wall.   The  organs  connected  with  the reproductive system are found in the posterior region of the abdominal cavity on both sides of the alimentary canal.  Though these arrangements are characteristic of all Arthropods, including insects, they are quite different in the higher animals (Fig.23)

‘Integument’, the outer layer of insects consists of the ‘basement membrane’, ‘epidermis’ and the ‘cuticle’. One of the most important characteristics of insects is the presence of the rather hard, flexible chitinous exoskeleton or cuticle, which covers the entire body and provides support to the body. The exoskeleton of insects that is akin to the internal skeleton of vertebrates accounts for their size and shape. Movement is made possible by the division of the cuticle into separate plates or sclerites.  Primarily these  sclerites  are confined to segments and the sclerite of one segment is connected to the sclerite of the adjoining segment by means of an articulate called ‘suture’, a region in which the cuticle is very thin and flexible. The cuticle of each segment is divided into four primary sclerites viz., a dorsal tergum, two lateral pleura and a ventral sternum. The dermal glands present in the epidermal layer secrete the entire cuticle of the insect.

Like that of the body, the cuticular skeleton of the appendages is divided into tube-like segments connected to one another by articular membranes, thus creating a joint at each junction. Such joints enable the segments of the appendages, as well as those of the body to move freely.

In addition to the exoskeleton, an endoskeleton is also developed. This may be an infolding of the procuticle that produces inner projections or ‘apodemes’ equal to bones in vertebrates on which the muscles are inserted.

Insects came into existence in this world some 250 - 500 million years ago, while man appeared in this planet only about a million years ago and intruded into the domain of insects. From this time onwards, a rapport had started between the insects and man. Man considered insects obnoxious and not worth consideration in the early days. However, the real impact of insects on the activities of man became manifested to a greater extent only during the past few thousands of years. Gradually man began to understand the nature of insects and started looking at insects, both as his adversaries and as his beneficiaries. He started exploiting the useful insects for his own benefit and tried to destroy those, which are harmful to him.
 
There are numerous references in the ‘Ancient Epics’ and ‘Puranas’ such as, ‘Ramayana’, ‘Mahabharata’ etc. to show man’s acquaintance with insects even from very early days. Several references to insects are found in the ‘Holy Bible’ also. Ancient people of India were quite aware of insects, which provide honey, lac and silk. They were familiar with honeybees and gathering of honey and bee wax from hives. Honey was used in most of the religious rituals. Honey and bee wax were used in many Ayurvedic medicines against various diseases. The story of the lac palace constructed by the Cauravas to destroy the Pandavas by setting the wax palace on fire at night as narrated in Mahabharata is quite well known. The ancient Indians knew how to manufacture silk from silk thread produced by silkworms. Records show that an Indian king had sent some silken stuff to a Persian ruler even as early as in 3870 BC. References to insects such as, flies, beetles, bees, wasps, moths, ants etc. are found in old Sanskrit literature. The Ancient people also used some Mercury, Arsenic and Sulfur compounds for the control of some of the harmful insects. Numerous references to insects are found in the ‘Holy Bible’ also. King Solomon, the wise (971 BC), who ruled Israel had told his people to learn from the ways of ants, which are so active and orderly (‘Proverbs’, Chapter 6). He had mentioned as to how the ants gather and store food at the time of harvest, when food is available in plenty to be used in summer when food is scarce (‘Proverbs’, Chapter 30).

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Ananthanarayan, R. and Paniker, C.K.J. 2005. Textbook of Microbiology (VII Ed.) Orient Longman Pvt Ltd, Chennai-600 002. pp 1-657.
Asthana, R.K., Srivastava, A., Singh, A.P., Deepali, Singh, S.P., Nath, G., Srivastava, R. and Srivastava, B.S. 2006. Identification of an antimicrobial entity from the cyanobacterium Fischerella sp. isolated from bark of Azadirachta indica (Neem) tree. Journal of Applied Phycology. 18, Number-1, 33-39.
Ayehunie, S., Belay, A., Baba, T.W., and Ruprecht, R.M. 1998. Inhibition of HIV-1 replication by an aqueous extract of Spirulina platensis (Arthrospira platensis). J. Acquir. Immune. Defic. Syndr. Hum. Retrovirol. 18, 7-12.

The objective of the present investigation was to evaluate the antibacterial properties of cyanobacterial species viz., Anabaena variabilis, Anabaena fertilissima, Nostoc muscorum, Nostoc punctiforme, Nostoc linckia, Nostoc commune, Spirulina platensis., Westiellopsis prolifica and Hapalosiphon sp. against some pathogenic species including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pnumoniae and Salmonella typhi. The following are the major findings of the study.

    •    Extracts prepared in methanol were found more active as compared to ethyl acetate, hexane and dichloromethane.
 
    •    Antibacterial activity of extracts varied with the test organisms. Maximum antibacterial activity was shown against Staphylococcus aureus followed by Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi. Klebsiella pneumoniae was found to be least susceptible against all tested cyanobacterial extracts.

    •    Antibacterial activity was observed against both Gram-positive and a spectrum of Gram-negative bacteria by almost all the cyanobacterial species examined in the present study except Westiellopsis prolifica where activity was observed only against S. aureus, a Gram-positive bacterium.

Present work was aimed to determine the antibacterial activity and minimum inhibitory concentration (MIC) of active crude extracts of selected cyanobacterial species. Nine cyanobacterial strains viz. Anabaena variabilis, A. fertilissima, Nostoc muscorum, N. punctiforme, N. linckia, N. commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. belonging to family; Nostocaceae, Oscillatoriaceae and Stigonemataceae were selected from the herbarium of Indian Agricultural Research Institute, New Delhi, and maintained in BG-11 growth medium throughout the study in the laboratory.

In the present investigation, nine cyanobacterial species viz. Anabaena variabilis, Anabaena fertilissima, Nostoc muscorum, Nostoc punctiforme, Nostoc linckia, Nostoc commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. were tested for their activity pattern against some selected bacterial species.
 
Each cyanobacterial species was initially subjected to determine the early stationary phase of their life-cycle, which is believed to be the most appropriate period for the production of secondary metabolites by an organism. The growth curve for each cyanobacterial species was prepared by culturing them in BG-11 growth medium. Optical densities (OD) recorded at 650 nm were plotted against number of incubation days for each cyanobacterium. After 23-25 days of incubation period, each culture was harvested to obtain the biomass and spent medium, which were then subjected to process of extraction by using various solvents viz., Hexane, ethyl acetate, dichloromethane and methanol. The extracts and spent medium thus obtained were then investigated for antibacterial activity against five pathogenic bacteria including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pnumoniae and Salmonella typhi.

Nine cyanobacterial strains viz., Anabaena variabilis, A. fertilissima, Nostoc muscorum, N. punctiforme, N. linckia, N. commune, Spirulina platensis, Westiellopsis prolifica and Hapalosiphon sp. were cultured in the laboratory. The growth curve for each culture was studied by growing them in Erlenmeyer flask using BG-11 growth medium. They were examined to determine the early stationary phases of their life-cycle, which are believed to be the most appropriate period for the production of secondary metabolites by an organism. After 23-25 days of incubation period, each culture was harvested and spent medium was collected by filtration of the biomass. Hexane, ethyl acetate, dichloromethane and methanol were used as the solvents for obtaining the extracts from biomass and spent medium of each culture which were then investigated against five pathogenic bacteria viz., Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella typhi. Antibacterial activity of different cyanobacterial sp. has been shown in various tables.

Culture Media and Reagents

The media used throughout the study were procured from Hi- Media Laboratories, Mumbai, India and the chemicals used were procured locally. Composition of each medium is as follows: