Preface It gives us immense pleasure to put before you. “Entomology: An Illustrated Texbook” The book has been written in simple and lucid language keeping in view all the grades of students. While writing this book, a number of text books, journals, encyclopedias have been consulted. We therefore express our gratitude to the authors, eminent scientists and the publishers of those books who have put their efforts in producing such scientific literature. It is hoped that this textbook will serve the purpose of students at under–graduate and post-graduate levels of different Indian universities. The keen interest and the sincere devotion of the publisher of this book needs the special appreciation. We are very much thankful to all those who have directly or indirectly helped us in bringing this book.

Grasshoppers are highly voracious herbivores having the world wide distribution. It is particularly found across — Asia, Africa, Europe and Australia. In India it may be seen in abundance during monsoon season. This pest is of International importance and the following three species are commonly found in India of which desert grasshopper is predominant all over the country.

The integument is composed of the cuticle and under lying epidermal cells that secrete the cuticle. The integument is a complex vulnerable organ system of diverse function. The insect outer body covering is called integument. The integument is a central subject intimately related to a variety of applied - Problems such as the mode of action, insecticides, ecology, cuticle and endocrine glands present in the body of insects. The insect integument consists of 3 parts and plays crucial role in locomotion, breathing and respiration, feeding, excretion, protection from desication behaviour of insect. Epidermis Layers Basement Layers Cuticle Membrane

ORIGIN OF INSECT Entomology is a branch of zoology which deals with insects. In this branch we study the insect origin and evolution of insect and their diversity and classification and other parts of insect body. Insects belong to the class insecta in the phylum arthropoda, the largest group in the animal kingdom. All arthropods are characterised by having segmented body, claws, chitinous exoskeleton, ventral nervous system and dorsal heart. The class insecta is generally considered to have evolved from myriapod of some sort during the Devonian period. Based on different mandibles and mandibular movement concluded that insects are not direct insect group myriapods the mouth is located between the prostomium and the first body segment and the anus open in the periproct. The first great step was the development of a pair of ventral appendage. Insect legs on each body segments and locomotion, parallel to this an improvement in the sense organs of the head occured eyes and Antenna were the ultimate result this level of organisation is met in onychophora. A series of diagramms is helpful in a very simplified way in visualising the hypothtical origin of insects.

The digestive system of insects comprises of two main sub-parts, one is the alimentary tract or also known as the digestive tract and the associated digestive glands. These digestive glands may be associated directly or indirectly such as, salivary glands, gastric, caeca (directly) and Malpighian tubules (indirect). If we have to describe an insect and its anatomy, or its histology, it is based on the orthopteroid plan, which is mostly shown by grasshoppers, crickets, and locusts, because their plan shows and describes the basic, primitive design from which other groups of insects have enolved and showed modifications and specialization. We can say that this orthoptera insect shows the general anatomical and histological features of a generalised insect.Today, we see that insects have invaded and adapted in almost all types of habitats and the major reason for their biological success is their ability to show digestion, utilization and their ability to eat an extremely vast diversity of food. It is due to this abilityof extremizm in food diversity that insects have undergone many specializations and modifications of the alimentary canal. What modifications a species of insects undergoes, depends upon the type of insects, depends upon the type of food it consumes. The diversity is also seen in the way of obtaining, storing, processing and absorbing the food. These differences may be structural or functional or both. It is not necessary that these differences must be present in different species only, those may be shown by different life stages of a single insect, by two sexes of a single species, etc. e.g., the difference between the mouths parts of mosquito species.

Insects, belonging to the phyllum-arthropoda, have an open circulatory system. An open circulatory system is that in which blood bathes the organs rather internal organs directly in the haemocoel, the coelom of the insects, which actually is not a true coelom. Almost entire haemocoel of insects is formed from the epineural sinus. The haemocoel is divided into the perineural sinus and perivisceral sinus by the dorsal and ventral diaphragm respectively. The characteristic of insects is the presence of dorsal vessel, which comprises of anterior aorta and a posterior heart and is the only conducting tube present in insects. The blood of insects mostly does not perform gaseous exchange, therefore it does not contain haemoglobin, and blood in insects is called the haemolymph, which is red-coloured. So in order to study the circulatory system of insects, the major focus must be on the dorsal vessel, which has been described as follows, along with its accessory structures.

Excretory system of an organism maintains its homeostasis i.e., a constant internal environment. Here in insects, the blood is haemolymph therefore it determines the excretion of an insect’s body. Excretion also eliminates the nitrogenous wastes and maintains the salt- water balance and also regulates the uniformily of haemolymph. The characteristic feature of insects is the presence of malpighian tubules to eliminate the metabolic wastes, whereas rectum walls carry out the function of reabsorption of salt and water. A minimum amount of water is excreted with nitrogen waste in order to conserve the water in body.

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.

In insects nervous system is highly developed and serves to coordinate the activities of its various systems. Units of this system are known as neurons. Which carry information in the form of electrical impulses from external and internal sensilla (Sensory cells) to appropriate effectors e.g., glands, muscles and glail cells. Nervous system of insects may be divided into three parts. Central nervous system Sympathetic or visceral nervous system Peripheral nervous system.  

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. 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: According to Ernst Haeckel, 1869 “The total relations of the animal to both its organic and inorganic environment is called as ecology”. E. Warming 1895 “Ecology is the study of animals and plants in relation to their environment”. According to Odum 1963 “Study of structures and functions of nature is defined as ecology”. 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: Cultivation of silkworm food plants Rearing of silkworms for the production of raw silk Reeling the cocoons for unwinding the silk filament and Other post-cocoon processes such as twisting, dyeing, weaving, printing and finishing.

Selected References Askey R.R. (1971). Parasitic Insect, H.E. Books, London. Chaponan R.F. (1982). The Insect Structure and Function. 3rd Edition, Harvard Publishing Press, Combridge MA. Elzinga, R.J. (1978). Fundamental of Entomology. Prentice-Hall of India Pvt. Ltd. New Delhi. Ghorai N. (1995). Lac-culture in India. International Books and Periodicals Supply Service, New Delhi. Grimaldi D. and Engel M.S. (2005). Evolution of the Insects. Cambridge Univ. Press, New York. Kumar and Dhiman (2014). Biology, Ecology and Population Dynamics of C. stolli Wolf (Penta). Publisher: Scholar’s Press and LAP Publishing Company. Lagreca, M. (1980). Origin and Evolution of Wings and Flight in Insects. Bull. Zool. 47: 65-82. Mani, M.S. (1989). Indian Insects, Satish Book Enterprise, Agra. Mathur and Upadhyay. A Text Book of Entomology. Aman Publishing House, Meerut (India). Nigam, P.M. (1989). Text Book of Agricultural Entomology. Emkay Publication, New Delhi. Plak Prakash (2009). Laboratory Manual of Entomology Published by New Age International (P) Ltd., Publishers 4835/24 Ansari Road Daryagang, New Delhi 110002. Pruthi, H.S. (1969). Text Book on Agricultural Entomology, ICAR, New Delhi. Sehgal, P.K. (2014-17). Fundamental of Agricultural Entomology, Kalyani Publishers, New Delhi, pp. 1-401. Singh Rajendra (2012). The Elements of Entomology. First Edition. Rastogi Publications, Shivaji Road, Meenit (India). Singh S. Bee Keeping in India ICAR, New Delhi (1975). Srivastava, K.P. (1993). Text Book of Applied Entomology, Vol I and II. Kalyani Publishers, Ludhiana, India. Tembhare B.D. (2012). Modern Entomology. The Publishing House Pvt. Ltd., Delhi. Winston M.L. (1987). The Biology of Honey Bee. Cambridge Univ. Press. B.Sc. (Agriculture) (Second Semester)