eChapters

Insects show sexual Dimorphism i.e., the sexes are usually separate and are dioecious. Male reproductive system produces sperms, stores them and delivers them i.e., spermatozoa. It also produces the seminal fluid, which provides a suitable environment to the sperms and nourishes them. Male reproductive system also situmilates are the female for oviposition. The female reproductive system produces and stores eggs provide nutrition to them for embryonic development, recieves and stores the sperms, is a site of fertilization. Female reproductive system also deposite eggs and may provide additional protection to the embryos. The reproductive system of both male and female insect’s bearis a gononpore, which is an opening of a pair of gonads. Both the gonads open into the gonopore by a median duct. For the secondry sexual purposes, e.g., formation of spermatophore and egg-case or ootheca, some accessory glands are associated with the reproductive system.

The respiratory system or tracheal system is involved in gaseous exchange in the insect with the environment. In this system there is a system of internal tubes, the tracheae that directly transport the oxygen to the parts of the body. Therefore, it does not use the circulatory system as the vehicle for gaseous exchange. The trachae open outside through segmental pores called spiracles having some system of closing and opening. Except proturans and some collembolans all insects possess tracheal system for respiration. These insects live in moist habitats where gaseous exchange takes place directly with the environment via the integument.

Exocrine Glands Types: Exocrine glands are generally of ectodermal origin and are widely scattered over the insect. Exocrine glands release their secreations through ducts into the lumen of various internal organs. Example: Accessory reproductive glands, salivary gland, silk gland. Gland is mainly composed of secretory epithelial cells. These are simple unicellular, bicellular, multicellular, complex multicellular (compound glands). These glands are ectodermal in origin and are secreated over the insect body.

Examples. Wax glands, lac glands, cephalic glands, poison glands.

1. Glands pouring (secreting structural materials). Some insects secrete substances that are used in building their houses (beehive) as protecting them (lac or cocoon).

The term ecology was first of all proposed by zoologist H. Pietir in 1865. It was derived from the Greek word ecologic means oikos = living place and logos = study and some definitions of ecology presented below:

1. According to Ernst Haeckel, 1869 “The total relations of the animal to both its organic and inorganic environment is called as ecology”.
2. E. Warming 1895 “Ecology is the study of animals and plants in relation to their environment”.
3. According to Odum 1963 “Study of structures and functions of nature is defined as ecology”.
4. Krebs 1985 says that the “Ecology is the scientific study of interaction that determine the distribution and abundance of organisms”.

The life of insects is dependent on the adaptability of the environment, if the environment is unfavourable then the insect population ceases and vice-versa. This insect move one place to another to get the favourable environment so that they can pull on their life activities properly. There is a deep relationship between the living community and non-living environment. Both are affecting each other greatly. This inter-relationship between living community and non-living environment is called as ecosystem. The term ecosystem was first used by A.G. Tansley as early as 1935 and he defined, “Ecosystem is the system of resulting from the interaction of all the living and non-living factors of the environment”.

Many insect can be observed at any hour of the day. This is proper understanding of the taxonomy and biology. The insect collection, storage and preservation are useful technique of their culture. The best period for collection is from early spring to late rainfall and the best time of the collection of most of the species is during the daytime. The insect are polyphagous and therefore, plants provide one of the best collecting places. Insect can be picked, swept off the plant with the help of a net. Different species feed on different kinds of plant, one should therefore, examine all sorts of plant, flowers weed shrubs and trees. Few insect are only found in the stem, bark, wood, fruit or roots etc. Some species can be found in the leaf mud and litter on the surface of the soil, particularly in woods or areas where the vegetation is dense, others can be found under stones bark etc. other house hold insects may be observed feeding on clothing, furniture, grain, food and other parts of Plant and House and some are aquatic insects.

The original divisions of the class insecta are a matter of dispute and it is not easy to decide which division to use many, different original order and groups are recognised by different experts and which one is best will no doubt remain problem. The words taxonomy, systematics and classification have been used alternatively for the same subject by various scientists. However Simpson 1964 has attempted to segregate these. According to him classification is the order of animals into groups on the basis of their relationship that is association of contiguity similarity or both. Systematic is the scientific study of the kinds and diversity of organism and of any and all relationships among them, while taxonomy is the theoretical study of classification including its bases, principal procedures and rule. All animal species are segregated into small and large groups on the basis of their comparative similarities and dissimilarities. The largest group is called phyllum as followed by class, order, family, genus-species and sub-species respectively. The Phylum, class, order, genus, species etc. The division of class insecta into primitive wingless insects, the apterygota and the secondary winged-insects the pterygota and included some orders. The class insecta may be divided into two subclasses.

Efficiency of pest control by insecticides is dependent on the correct type of pesticide formulation applied at the proper time and correct dosage, besides the good equipment. Equipment used to apply insecticides must be suited to the crop (or other situation in which the pest is to be controlled), to the scale of operation, and to the formulation of chemical to be applied. In the long run, it is good economy to buy the best equipment available.

Application equipment of high quality means not only good, durable construction but also good design that gives it a professional appearance. Because it is desirable and often necessary to utilize pesticides in a variety of ways, various types of dispensing equipment have been developed. This equipment is placed in the following categories: (1) Sprayers, (2) Dusters, and (3) Granule Applicators. In addition, specialised equipment of various sorts (such as mist machines and fog generators) are available for particular purposes. Since detailed consideration of pesticide application equipment is out of the scope of this book, only a brief consideration is given here to some important features of the main types of equipment.

The insect larva after the complete development emerges out from the egg by rupturing the egg shell chorion. It passes through several stages called as instars. Each instar is separated by a moult; the growth from larva to adult involves some degree of morphological changes or metamorphosis. The egg hatches into 1st instar larva which later moults to the second instar larva and so on until at a final moult the adult imago stage. The insect moult takes place after attaining adult except in the insect apterygote insect. In family pantatomide full insect moulting occurs. Many insects especially those with a small number of instars (mosquitoes) and (chrysocoris stolli) insect moulting occurs as Ist, 2nd, 3rd, 4th and 5th imago instar and then after sometime adults insect emerges.

Metamorphosis of Insect: The development process by which first instar immature stage is transformed into the adult is called metamorphosis, which means literally change in the form. The developing stage is morphologically different from the adult. The degree of difference varies from slight to extreme with many intermediates stage. E.g., Cockroaches, Butterfly, Chrysocoris stolli Wolf. The insect may be grouped on dependance of degree of metamorphosis as:

Locusts are injurious to man as it destroys several human commodities. Locusts are phytophagous and feed on several plants cultivated by man. The locusts are insects belonging to the order orthoptera. The most popular insect is grasshopper. The only difference between the two types of insects is that locust can exist in two different behavioural states whereas grasshoppers do not. When the population density is low locusts behave as individuals, much like grasshopper. As the population density is high locusts gregariously behave as band of nymphs or swarms of adults. The changes in body shape and colour and in fertility, survial and migratory behaviour are accompanied by phase change. The most important locust species is the desert locust (Schistocerca-gregaria). The international pest influences various parts of Asia, Africa and Europe. Other locust species are highly injurious to mainkind like Bombay locust and Indian migratory locust (Locusta- migratoria) found all over India in its solitary phase. The monsoon months in July and August suitable are for locust multiplication conditions. The new generation produced migrate eastward into the Indian desert areas in May and June.

DEFINITION

Pheromones are chemical produced as messengers that affect the behavior of other individuals of insects. The term pheromone was introduced by Peter Karlson and Martin Liischer (1959) and is based on the Greek pherein (to transport) and hormon (to stimulate) is a chemical that triggers a natural behavioural response in another member of the same species. There are alarm pheromones, food trail pheromones, sex pheromones. And many are others that affect behaviour or physiology. Their use among insects has been particularly well documented, although many vertebrates and plants also communicate using pheromones. Pheromones are chemicals released by an organism into its environment enabling it to communicate with other members of its own species.

COMMON INSECT PESTS AND THEIR CONTROL

Since, insects are the most successful and one among the strongest rivals of man in the competition of existence. Due to their immense tendency of producing numerous viable propagules (eggs) i.e., their high fecundity, their population graph takes a sharp peak in a very short span of time.

A time reaches when the population of an insect type reaches to the level where from it starts causing inconvenience or injury to man, plants, domesticated animals and other human belongings, at such a juncture they are termed as insect pests.

Many, workers are of the view that “insects capable of causing 5 or more than 5% of damage to the crops, stored products, domesticated animals and other human dependences will be termed as pests”. Thus, if an insect causes a loss of less than 5% will not be considered as a pest. Moreover insect pests which cause a damage of 5-10% are said to be minor pests and those which cause a loss of more than 10% of yield are said to be major pests.

Silk is a way of life in India. Over thousands of years, it has become an inseparable part of Indian culture and tradition. No ritual is complete without silk being used as a wear in some form or the other. Sericulture and Silk Textiles Industry is one of the major sub-sectors comprising the textiles sector. Sericulture is an agro-based cottage industry. Sericulture refers to the mass-scale rearing of silk producing organisms in order to obtain silk. Sericulture is an agro-based labour intensive industry. The major activities involved in a sericulture industry are:

1. Cultivation of silkworm food plants
2. Rearing of silkworms for the production of raw silk
3. Reeling the cocoons for unwinding the silk filament and
4. Other post-cocoon processes such as twisting, dyeing, weaving, printing and finishing.

India is an agricultural country and nearly 70% of its population is dependent directly or indirectly on agriculture and related activities. At present, about 173 million hectares of land is under agriculture of which about 143 million hectare are cultivated without fallow. Mounting pressures of teeming population and shrinking land (due to urbanization) have necessitated the production of increasingly more food per unit area. In the efforts to increase the food production and make the country self-sufficient in food grains, modern technology adopted since ‘Green Revolution’ in the middle sixties has paid a significant role. Higher yields in almost all crops were possible with exotic and high yielding genotypes and availability of seeds, heavy doses of fertilizers, frequent irrigation, labour and repeated applications of pesticides. However, several genotypes particularly hybrids proved to be susceptible to pests and disease pathogens. Insect-pests, diseases and weeds are important biotic-constraints inflicting 20-25% losses in agricultural production. Farmers were therefore compelled to use pesticides extensively and frequently.

Plant protection is an integral part of the crop production and pesticides proved to be valuable means in plant protection to ensure plenty food. However, some of the pesticides are highly hazardous and their residue remains undetected and posses risk to human safety and health. Moreover, the repeated and incorrect applications without following need-based criteria have resulted in several secondary side effects ². For instance, increased resistance of pests to insecticides, harmful to beneficial and non-target insects and animals, undesirable effects on crop plants and environmental hazards. Safety has become a major worry in factories and outside the working places. Besides these, repeated and heavy pesticide applications add to the cost of production and misery to farmer. These ill effects of synthetic pesticides have aroused interest in alternate methods of plant protection.

Introduction

In agriculture and public health sectors, a variety of pesticides are still in uses that are toxic chemicals and having broad-spectrum actions. They kill target species but also harm the ecosystem seriously by affecting desirable organisms, thus, badly impairing prey-predator relationship. Most of these pesticides are persistent or non-biodegradable and hence exhibit biological magnification by accumulating at higher concentration in the organism, which are on the top of the food chain. The other drawbacks of repeated use of pesticides are eradication of natural enemies of pests, increased level of pesticide residues in soil, water, food and fodder crops, resistance of pests to pesticides and resurgence of minor pests in addition to the environmental pollution. It is clear that once used pesticide may persist, somewhere causing serious harm to the mankind and his ecosystem.

The increasing incidence of pesticide harms is fueling the need for new pesticides, which are toxicologically safe, more selective and efficacious and environment-friendly. Now the natural compounds, thus, have increasingly become the focus of those interested in discovery of pesticides. Tens of thousands of secondary products of plants have been identified and there are estimates that hundreds of thousands of these compounds exist. There is growing evidence that most of these compounds are involved in the interaction of plants with other species-primarily the defense of the plants from plant pests. Thus, these secondary compounds represent a large reservoir of chemical structures with biological activity. This resource is largely untapped for use as pest management agents^3, 4. The extraction of such chemicals from plants and derivatives of potent compounds are being encouraged all over the world under the Integrated Pest Management (IPM) approaches. The natural compounds and their synthetic derivatives are more selective in action, completely biodegradable and environment-friendly. In short, natural ways of pests control have already been established and are receiving much attention these days.

Introduction

In man’s continued effort to enhance food production, new high yielding crop varieties and new techniques for crop and field management are being constantly evolved resulting in a parallel increase in disease occurrence which calls for their efficient management. Of the various management strategies available for disease management, the chemical strategies have so far dominated our thinking. Over emphasis on chemical control of plant diseases has caused serious imbalances in the agro-ecosystem^1-2.

The shift to exploration of non-chemical strategies is likely to correct the imbalance in our approach and subsequently improve the understanding of Integrated Disease Management (IDM). IDM is defined as ‘a disease management system that utilizes all suitable techniques in a compatible manner to reduce and maintain pest pathogen population at levels below those causing economic injury.’ Fungi are the important group of pathogens.

In continuation of our work on natural pest management agents the present investigation aims at the preparation of different types of aqueous extracts of locally available four Indian medicinal plants viz., Datura stramonium Linn (Datura), Ricinus communis Linn. (Castor), Vitex trifolia Linn. (Nirgudi) and Nerium indicum Mill. (Kanher); study of stability of these extracts at room temperature; and evaluation of their anti-fungal potencies. This study will help to preserve and increase the pest management potency and efficacy of natural products.

Introduction

The biological systems on the earth are in a dynamic equilibrium. In this attempt to live comfortably man disturbs this equilibrium in many, one of which is the cultivation of crop plants to meet his requirements for food, clothing and shelter. Intensive and extensive n of crop plants provides not only better crops but also better ties for pests and diseases to attack these crops. The greater loss due to the pests and diseases, the greater the attempt to these damages. Bacteria are one of the important disease since time immemorial. Bacteria are found in every ble habitat. They are unicellular, but display a variety of ‘cal forms.

The present investigation on the botanicals  has been aimed at preparation of different types of aqueous extracts of locally available medicinal plants viz., Datura stramonium (Datura), Ricinus Castor), Vitex trifolia (Nirgudi) and Nerium indicum (Kanher); the study concentration and stability of these extracts at room temperature; and evaluation of their anti-bacterial activities. This study will be helpful to preserve and increase the pest management potency and efficiency of plant derived products.

Introduction

There are a number of estimates of post-harvest losses. The most conservative estimates for the handling losses at about 10 per cent, a quantity good enough to feed at least 60 million people. Storage loss occurs due to quantitative and qualitative damages caused by insects, mites, fungi, rodents, birds, heat, moisture, etc. Several hundred insect species have been reported to be associated with stored grains and milled and processed foods, but some 50 of these species are considered injurious. Under Indian conditions, the most important insect pests of stored grains are Sitophilus oryzae (Rice weevil), Tribolium castaneum (Red flour beetle), Rhizopertha dominica (Lesser grain borer), Callasobruchus spp. (Pulse beetle), etc.

The use of repellents to ward off insects has been a very old practice of mankind. The simple fly swatters, feather dusters, hand fans, mosquito nets etc., are some of the physical repellants still in use. In our own country, mustard oil or turmeric (haldi) water is also used as a mosquito repellent. Fire and smoke are the two oldest insect repellents known to man. To get rid of wasp nests from our dwelling or ward off honeybees during honey extraction, smoke is normally employed. Similarly sandal dhoop is often burnt to purify air (i. e. to ward off insects) in our houses.

Chemicals that prevent insect damage to plants or animals by rendering them unattractive or offensive are called repellents. A more broad-based definition would be: non-poisonous or mildly poisonous chemicals that induce avoiding (oriented movements in insects away from their source. Repellents are more important in the protection of man and his animals from insect attacks than in the protection plants.

Introduction

The food problem in the world is expected to become more serious if the world population keeps growing at the present rate. Out of various strategies to solve the problem, the post-harvest handling of the grains is of paramount importance. Tribolium species is major pest of stored grain and grain products in the tropics. Control of this insect relies heavily on the use of synthetic insecticides, which has led to many problems such as increasing costs of application, pest resurgence, pest resistance to pesticides and lethal effects on non-target organisms in addition to direct toxicity to users and disturbances of the environment. Thus, insecticides of natural origin are rational alternatives of synthetic insecticides. Several botanicals, natural products and their derivatives have been reported and exhibit better efficacy and potency against the stored grain pests.

In the present investigation, an attempt has also made to test ovicidal, larvicidal and adult emergence suppression potentials of the extracts of some of the locally available Indian medicinal plant viz., Datura stramonium, Ricinus communis, Vitex trifolia and Nerium indicum against T. castaneum against T. castaneum, commonly called as Red flour beetle.

Since the wide introduction of organochlorines and other synthetics in early 50’s farmers have heavily relied on the chemical pesticides for pest control. Over emphasis on chemical control has caused serious imbalances in the agro-ecosystem. The enormous quantities of chemicals, poisonous to microbial life, that fall on earth gets mixed up well with soil. Some problems like non-target effects of chemicals as well as latrogenic diseases are being experienced. Coupled with these, the increasing awareness of impeding pollution, health hazards and development of resistance have intensified the search for alternative strategies.

In the present investigation, the attempts have been made to test the stability and pest management efficacy of the plant extracts of some Indian medicinal plants, namely, Datura stramonium, Ricinus communis, Vitex trifolia and Nerium indicum. In the earlier chapters detailed methodologies and the results have been elaborated. This chapter embodes the comprehensive inter- and intra-comparative results and discussion on the basis of selected plants, extraction media, pest species and bioassay followed by conclusions.

The hot sterilized water extracts of R. communis were found to be more stable (i.e. 20 days to start the fermentation). In overall study the plant extracts were stable or viable means active for three to four weeks only. In most cases, the activity of cold and hot water extracts was found to be increasing with fermentation however the decrease in the activity of some extract was also observed.

The highest mean anti-fungal activity was reported for R. communis extracts followed by D. stramonium and N. indicum aqueous extracts, whereas no any anti-fungal potency was reflected by V. trifolia against test fungi species. R. communis and N. indicum extracts, the cold water method extraction showed greater positive effects in terms of mean anti-fungal potency as compared to the hot water extracts. The water extraction of D. stramonium was found to be more effective in anti-fungal activity study.

Pesticides offer one of the best means of controlling plant diseases and pests and subsequently improving the yield. They have been used since the 19^th century. Pesticides, undoutly are poisonous and their indiscriminate use and abuse may result in ecological imbalance resulting in pest resurgence, aggravation of minor pest, pesticides resistance, environmental pollution, poising serious health hazards to man and animals. However, if used judiciously, following the guide line of Pesticide Action Network (PAN), such problems are not likely to occur, and instead improve crop yield. It is however unfortunate that many of us really lack the insight in Materia Medica of plant diseases and pests and most of the problems have occurred due to misuse and abuse of pesticides for which man is responsible and not the pesticides.