Fundamentals of Entomology Theory Notes PDF

Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Course No. : ENTO-121 Course Title: FUNDAMENTALS OF ENTOMOLOGY Course Credit: 1+1=2 Teaching Schedule (Theory): Lecture No....

Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Course No. : ENTO-121 Course Title: FUNDAMENTALS OF ENTOMOLOGY Course Credit: 1+1=2 Teaching Schedule (Theory): Lecture No. Name of Topic 1&2 Introduction * Introduction and history of Entomology including contribution of scientist in brief (Aristotal, Carlous Linnaeus, Fabricious, Charles Darwin, Lefroy, Wigglesworth, Snodgrass, Pradhan, Runwal., Pruthi and Ananthkrishnan. Definition : Insect & Entomology Characteristics of Class - Insecta * Economic importance of insects : harmful, beneficial and productive insects * Pests of national importance e.g. Locust, termite and white grub along with their extent of losses. * Premier Institutes concerned with Entomology : International – CAB (UK), IOBC(Trinidad), International Institute of Insect Physiology – Kenya. National – National Institute of Biological Control (Bangalore) NCIPM - (New Delhi), CIB (Faridabad), National Plant Protection Institute, Hyderabad, Indian Grain Storage Institute (Hapur), 3 Dominance of Class Insecta 4 Insect Integument Structure, chemical composition and functions of Cuticle Process of moulting, cuticular appendages and processes 5 Body segmentation and structure of Head Body regions, structure of head capsule, and positions of head and structure of cervix 6 Structure of thorax and abdomen Segmentation, appendages and processes, pregenital & post genital appendages and structure of genitalia 7 Structure and modifications of Antennae Components of typical antenna, basal articulation, functions and modifications (with examples) 8&9 Structure and modifications of mouth parts Structure and feeding mechanism of Mandibulate type of mouthparts and Haustellate type of mouth parts (piercing & sucking ; chewing & lapping; sponging; rasping & sucking and siphoning) 10 Structure and modifications of leg Components of typical leg, basal articulation, tripod locomotion and modifications (with examples) 11 Structure and modifications of wings Basal articulation, regions, hypothetical wing venation, wing coupling apparatus and modifications (with examples) 1 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 12 Sensory and Sound producing organs Sensory organs : Location and function (mechanoreceptors, audio receptors chemo receptors, thermo & humidity receptors, photoreceptors and vision & visual organs, with examples Sound producing organs : Tympanum & Stridulatory organs 13 Metamorphosis and Seasonal adoptions Definition and types of metamorphosis with examples. Seasonal adoptions (aestivation, quiescence, hibernation and diapauses) with examples 14 & 15 Immature stages of Insects Structure of egg, eclosion and its type (with examples) Types of larvae and pupae (with examples); nymphal stage 16 Structure and functions of Digestive system Alimentary canal: salivary glands, proventriculus, filter chamber, digestion and absorption of food. 17 Structure and functions of Circulatory system Organs of circulations, composition of blood and functioning of dorsal vessel 18 Structure and functions of excretory system Organs of excretion and their functioning; products of excretion 19 Structure and functions of Respiratory system Organs of respiration and types of respiration (with examples) 20 & 21 Structure and functions of Nervous system Organs of nervous system, types of neurons and conduction of nerve impulse 22 & 23 Structure of Reproductive systems in Insects Male and female reproductive systems and types of reproduction 24 & 25 Systematics: Importance and history of Taxonomy; development of binomial nomenclature along with its rules and regulations Definitions : Order, Family, Genus, Species, Sub-species and Biotypes 26 & 27 Classification Phylum Arthropoda along with its characters Class Insecta along with its characters 28 & 29 Characters of orders along with families of agricultural importance Orthoptera (Family: Acrididae), Dictyoptera (Family: Mantidae) 30 & 31 Characters of orders along with families of agricultural importance Odonata, Isoptera (Family: Termitidae) and Thysanoptera (Family:Thripidae) 32 Characters of orders along with families of agricultural importance Hemiptera (Family: Pentatomidae, Coreidae, Pyrrhocoridae, Lygaeidae, Cicadellidae, Delphacidae, Aphididae, Aleurodidae, Coccidae, Psedococcidae 33 Characters of orders along with families of agricultural importance Neuroptera (Family: Chrysopidae), Lepidoptera (Family: Noctuidae, Sphingidae, Pyralidae, Gelechiidae, Arctiidae. 34 & 35 Characters of orders along with families of agricultural importance Diptera (Family:Cecidomyiidae, Trypetidae, Tachinidae, Agromyziidae) Hymenoptera (Family: Tenthridinidae, Apidae, Trichogrammatidae, Ichneumonidae, Braconidae) 36 Characters of orders along with families of agricultural importance Coleoptera (Family: Coccinellidae, Chrysomelidae, Cerambycidae, Bruchidae, Scarabaeidae, Curculionidae) 2 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) INTRODUCTION  The word Insect derived from the Greek word insecare, means cut in pieces or engraved /segmented.  Insects belong to the Phylum Arthropoda(Artho= jointed, Poda= Legs) which is the biggest phylum of kingdomAnimalia. More than three quarters of the animals on earth are arthropods, and most of these are insects.  KingdomAnimalia is classified into twelve phyla.  Insect: -The insects are the tracheate arthropods in which the body is divided in to head, thorax and abdomen possessing two pairs of wings and three pairs of legs and single pair of antennae.  Entomology: -Greek word-(Entomon = Insect; Logos = Study) It is the branch of zoologyor biological science that deals with the study of insects.  Branches of Entomology:- 1.) Study and use of insects in crime investigations is known as Forensic Entomology. 2.) Study of insects related to live stock and veterinary animals is known as Veterinary Entomology. 3.) Study of insects in relation to Human beings is known as Medical Entomology. HISTORY OF ENTOMOLOGY  In ancient scripts like Ramayana and Mahabharata, some of the terms used were related to insects. They are;  Pipilika – Ant,  Pathanga – grasshoppers,  Madhumakshika – honey bees,  Umbakapalika - termite queen References of Insects in Ancient Indian Literature  Mahabharta : (1424 – 1366 BC) Mentions about silk, honey and lac  The Famous story of “Lakshgruha” i.e. House of Lac build by Kauravas to burn their cousins live, Pandavas.  Amarkosha Sanskrit dictionary provide references like Patanga and Bhramar of flies , Moths, beetles and Glow worms  Sushruta : Surgeon (100 - 200 AD) : Classified ants (Pipilika), Mosquitoes and Flies  Umaswati : Physician (0 - 100 AD) : Classified the Bees  Pests of national importance –  E.g. Locust, termite and white grub. 3 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Contribution of scientist: -  Aristotle (384-322 B.C.) –  He was the Father of biological classification.  First person grouped insects in Mandibulate and Haustellate types and winged and wing less groups.  He gave the terms like Coleoptera and Diptera  Carolus Linnaeus (1758) –  Father of Taxonomy  In his publication “Systema Naturae” 1758 includes 28 Indian insect species.  J. C. Fabricius (1745- 1808) –  Danish Entomologist described over 10,000 insect species.  Published “Philosophia Entomologia” in 1778.  World’s first Text Book in Entomology.  The first entomologist who made any extensive study of Indian Insects.  Classified the insects in to 13 orders based on type of mouth parts.  J.G. Koenig (1767-1779) –  J.G Koenig was the first to collect number of insects from Coromandel and Southern India.  For his memory Red cotton bug is named as Dysdercus koenigi  Snodgrass R. E. (1875) –  Great Insect Morphologist referred as a Father of Insect Morphology.  He wrote book - Principles of InsectMorphology  Lionel de Nicevelle (1901) –  Was appointed as the first entomologist to the Government of India.  Maxwell Lefroy (1903) –  Was appointed as the second entomologist to the Government of India.  First Imperial Entomologist  1906 publication of ‘Indian insect pests’P  1909 publication of Indian insect life’  Mithan Lal Runwal (1908) -  Outstanding work on Termites / White ants  Contributions to ecology, embryology and Locust study are noteworthy  Sir Vincent B. Wigglesworth–  Insect physiologist, work on blood sucking bug, Bed Bug.  Father of Insect Physiology  T.B Fletcher (1914) –  The first Govt. Entomologist of Madras state.  Wrote a book ‘Some South Indian insects’.  Second Imperial Entomologist. 4 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  T.V. Rama Krishna Ayyar (1940) –  Wrote a book ‘Hand book of Economic Entomology for South India’  H S Pruthi (1963)–  1934 - First Indian, Imperial Entomologist of Independent India  1963 - He become first Plant Protection Advisor to Government of India  ‘Wrote a Text book of Agricultural Entomology’  Dr. M.S. Mani's (1968)–  Wrote a "General Entomology"  Dr. S. Pradhan(1969) -  Wrote a "Insect Pests of Crops" and Father of ModernApplied Entomology in India  B. Vasantharaj David and T.Kumara Swami (1975) –  Wrote a‘Elements of Economic Entomology’  M R G K Nair (1975) –  Wrote a‘Insects and Mites of crops in India’.  K.K. Nayar, N. Ananthakrishnan and B. Vasantharaj David(1976) –  Wrote a‘General and applied Entomology’  1912- Plant Quarantine Act was enforced.  1914- Destructive Insects and Pests Act was enforced. (DIPA)  1916 - Imperial Forest Research Institute Established at Dehradun (Uttarakhanda)  1925 – Indian Lac Research Institute started at Ranchi, Bihar  1937 - A laboratory for storage pests was started at Hapur, U.P.  1937 -Entomology division was started in IARI, New Delhi  1939 – Locust Warning Organization established  1946- ‘Directorate of Plant Protection, Quarantine and Storage’ of GOI started.  1968- The Govt. of India enacted ‘Central Insecticide Act’ which came into force from 1st January, 1971. Establishment of entomological institutes  IOBC,West Indies(Trinidad)- (International Organization for Biological and Integrated Control of Noxious animals and Plants)  ICIPE,Kenya – International Centre of Insect Physiology and Ecology  NCIPM,New Delhi - (National Centre for Integrated Pest Management - 1988)  PDBC, Bangalore - (Project Directorate of Biological Control -1993), and thenPDBC are (NBAII) i.e. National Bureau of Agriculturally Important Insects(2009)&nowareNBAIR -National Bureau of Agricultural Insect Resources.  CIB, Faridabad – Central Insecticide Board  NPPTI, Hyderabad – National Plant Protection Training Institute - 1966  IGSI, Hapur U.P. - Indian Grain Storage Institute  1946 Directorate of plant protection Quarantine and storage(DPPQS), Faridabad  1937 Establishment of Entomology division at IARI New Delhi  CABI, UK – Commonwealth Agricultural Bureau International 5 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) ECONOMIC IMPORTANCE OF INSECTS The field of entomology may be divided into 2 major aspects. 1. Fundamental Entomology or General Entomology 2. Applied Entomology or Economic Entomology  Fundamental Entomology:-  It deals with the basic or academic aspects of the Science of Entomology.  It includes morphology, anatomy, physiology and taxonomy of the insects.  In this case we study the subject for gaining knowledge on Entomology irrespective of whether it is useful or harmful.  Applied Entomology or Economic Entomology:-  It deals with the usefulness of the Science of Entomology for the benefit of mankind.  Applied entomology covers the study of insects which are either beneficial or harmful to human beings.  It deals with the ways in which beneficial insects like predators, parasitoids, pollinators or productive insects like honey bees, silkworm and lac insect can be best exploited for our welfare.  Applied entomology also studies the methods in which harmful insects or pests can be managed without causing significant damage or loss to us. Economic classification of insects  Insects can be classified as follows based on their economic importance. 1. Insects of no economic importance:- There are many insects found in forests, and agricultural lands which neither cause harm nor benefit us. 2. Insects of economic importance:- A. Injurious insects a) Pests of cultivated plants (crop pests) Each cultivated plant damage by many insect pests which feed on them reduces the yield of the crop. E.g. cotton bollworm, Rice stem bores. b) Storage pests Insects feed on stored products and cause economic loss. E.g. Rice weevil, Pulse beetle. c) Pest attacking cattle and domestic animals Cattle are affected by pests like Horse fly, Flesh fly, Fleas and Lice. They suck blood and sometimes eat the flash. d) House hold and disease carrying insects House hold pests include cockroach, ants, etc. Disease carrying insects are like mosquitoes, houseflies, bed bugs, fleas etc. 6 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) B. Beneficial insects I) Productive insects i) Silk worm: - The silk worm filament secreted from the salivary gland of the larva helps us in producing silk. ii) Honey bee: - Provides us with honey and many other byproducts like bees wax and royal jelly. iii) Lac insects: - The secretion from the body of these scale insects is called lac. Useful in making vanishes and polishes. iv) Insects useful as drugs, food, ornaments etc., (a)As medicine e.g. Sting of honey bees- remedy for rheumatism and arthritis Eanthoridin - extracted from blister beetle –useful as hair tonic. (b)As food - for animals and human being. For animals- aquatic insects used as fish food. Grasshoppers, termites, pupae of moths. They have been used as food by human beings in different parts of the world. (c) Ornaments, entertainers -Artists and designers copy colour of butterflies. - Beetles worm as necklace. - Insect collection is a hobby. (d)Scientific research Drosophila and mosquitoes are useful in genetic and toxicological studies respectively. (II) Helpful insects (i) Parasites: These are small insects which feed and live on harmful insects by completing their life cycle in a host and kill the host insect. E.g. egg, larval and pupal parasitoids (ii) Predators: These are large insects which capture and devour harmful insects.E.g. Coccinellids and Preying Mantid. (iii)Pollinators: Many cross pollinated plants depend on insects for pollination and fruit set. E.g. Honey bees, aid in pollination of sunflower crop. (iv)Weed killers: Insects which feed on weeds kill them thereby killers. E.g. Mexican beetle eats on Parthenium (Gajar gavat). Cochineal insect feeds in Opuntia dillenii. (v) Soil builders: soil insects such as ants, beetles, larval of cutworms, crickets, collombola, make tunnels in soil and facilitate aeration in soil. They become good manure after death and enrich soil. (vi) Scavengers: Insects which feed on dead and decaying matter are called scavengers.They important for maintaining hygiene in the surroundings.E.g. Carrion beetles, Rove beetles feed on dead animals and plants. d) House hold and disease carrying insects i) Pests which cause damage to belongings of human being like furniture, wool, paper etc. E.g. Cockroaches, furniture beetle, sliver fish etc. ii) Pests which cause painful bite, inject venoms. E.g. Wasps, bees sting us. Hairy caterpillar nettling hairs are poisonous. Mosquitoes, bugs bite, piece and suck blood from us. iii) Disease causing Mosquito- Malaria, Filariasis, dengue fever. Housefly- Typhoid, Cholera, Leprosy, Anthrax. 7 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) INSECT DOMINANCE  Measures of dominance: 1. More number of species. 2. Large number of individuals in a single species: e.g. Locust swarm comprising 9 of 10 numbers of individuals, occupying large area. 3. Great variety of habitats 4. Long geological history  Reasons for dominance: There are several structural, morphological and physiological factors responsible for insect dominance. They are: 1. Capacity for flight 2. More adaptability or universality smaller size: Majority of insects are small in their size conferring the following physiological and ecological advantages. 3. Presence of exoskeleton: Insect body is covered with an outer cuticle called exoskeleton which is made up of a cuticular protein called Chitin. This is light in weight and gives strength, rigidity and flexibility to the insect body. 4. Resistance to desiccation: Insects minimize the water loss from their body surface through prevention of water loss (wax layer of epicuticle, closable spiracles, egg shell) conservation of water (capable of utilizing metabolic water, reabsorption of water from fecal matter, use less quantity of water to remove the nitrogenous waste) 5. Tracheal system of respiration: This ensures direct transfer of adequate oxygen to actively breathing tissues. Spiracles through their closing mechanism admit air and restrict water loss. 6. Higher reproductive potential: Reproductive potential of insect is high e.g. Egg laying capacity (fecundity) of queen termite is 6000 - 7000 eggs per day for 15 long years. Short development period e.g., Corn aphid produces 16 nymphs per female which reaches the adulthood within 16 days. Presence of special types of reproduction other than oviparity and viviparity like Polyembryony, Parthenogenesis and Paedogenesis. 7. Presence of complete metamorphosis: More than 82 per cent of insects undergo complete metamorphosis (holometabolous insects) with four stages. As the larval and adult food sources are different, competition for food is less. 8. Presence of defense mechanisms: By different defense mechanisms, insects escape from the enemies to increase their survival rate. 9. Hexapod locomotion: Insects uses 3 legs at a time during locomotion, while the remaining 3 legs are static, which gives greater stability. 8 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) INSECT INTEGUMENT  The vertebrates have internal skeleton known as endoskeletonwhile in insects it is located outside the body forming exoskeleton.  Insect cuticle provides space for attachment of muscles of antenna and mouthparts, called as tentorium.  Insect body wall iscalled as Integument or Exoskeleton. It is the external covering of the body which is ectodermal in origin. It is rigid, flexible, lighter, stronger and variously modified in different body parts to suit different modes of life.  Integument consists of 3 layers:- 1) Cuticle (Upper) 2) Epidermis (or) hypodermis(Middle) 3) basement membrane (Inner) 1. Cuticle:-  It is outermost thick layer of integument secreted by epidermis.  It is non-cellular.  It is divided in to two regions:-Epicuticle (Upper) and Procuticle(Inner) A. Epicuticle:  It is a thin outermost layer varying in thickness from 1-4μ. Chitin is absent in epicuticle.It consists of the following 4 layers 9 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  Cement layer:It is secreted by dermal glands and is composed of lipoprotein.It protects the body from external damage.  Wax layer: Itconsisting of long chain hydrocarbons, esters of fatty acids and alcohols. It serves as water proof layer preventing water loss from the body  Polyphenol layer: It is a non-static layer containing various types of phenols which are mainly used in the formation of the proteins.It is resistant to acids and organic solvents.  Cuticulin layer: It is an amber coloured thin layer over the surface of the epidermis which is strengthened by outer polyphenol layer.It serves the purpose of permeability and also acts as growth barrier. B. Procuticle:  It is differentiated in to exo and endocuticle.  Exocuticle: It is darkly pigmented, hard and sclerotized. This layer is made up of chitin and sclerotin.  Endocuticle: It is soft, light coloured and unsclerotized. This layer is made up of chitin and arthropodin.  Pore canals: These are numerous fine vertical channels traversing both exo and endocuticle. Pore canals present in the exocuticle helps in the deposition of epicuticle. They are useful in transportation of cuticular material and enzymes to the outer pro and epicuticle parts.  Composition of cuticle: ♣ Two major components of insect cuticle are; i) Chitin,ii) Proteins. i) Chitin:  It is a nitrogenous polysaccharide.  It consists of high molecular weight polymer of anhydro-N-acetyl glucosamine residues joined by β-glycosidic linkages.It is water insoluble but soluble in dilute acids, alkalies and organic solvents. ii) Proteins:Cuticle has 3 types of proteins  Arthropodin:An untanned protein means it is soft water soluble protein present in endocuticle. The conversion of arthopodin in to sclerotin is known as sclerotization or tanning.  Sclerotin:It is also called tanned protein which is amber coloured and present only in exocuticle.This is water insoluble.  Resilin:It is a rubber like elastic protein which is colourless and present in joints such as wing hinge ligaments, leg joints, clypeolabral joints or suture and tergosternal joints. 10 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 2. Epidermis (or) hypodermis:  It is an inner unicellular layer resting on basement membrane with the following function. i. Cuticle secretion ii. Digestion and absorption of old cuticle iii. Wound repairing iv. Gives surface look  Adjacent epidermal cells are held together by means of certain cytoplasmic processes which are known as desmosomes.  All the epidermal cells are glandular and secrete cuticle and the enzymes involved in production and digestion of old cuticle during moulting.  The epidermal cells get differentiated in to following types based on the function they perform and may modify in to; a)Dermal glands producing cement layer b)Trichogen cell producing hair like seta or trichome. c)Moulting glands secreting moulting fluid which digests the old cuticle d)Peristigmatic glands around the spiracles in case of Dipteran larvae 3. Basement membrane:  It is the basal part of the body wall formed from degenerated epidermal cells and appears as non-living amorphous (shapeless) granular layer of integument.  It is about 0.5µ in thickness and consists of fibrous protein, glycosaminoglycans which are polymers of disaccharides.  The basement membrane forms a continuous sheet beneath the epidermis, where muscles are attached and become continuous with sarcolemma of the muscles. Functions of Insect Integument o It provides protection to the internal organs enclosed by it. o It gives shape and size to the insects. o It provides surface for the attachment of muscles. o It conserves moisture and prevents desiccation. o It prevents entry of pathogens and insecticides. o It forms sense organ. o It contains pigments to make insects attractive. 11 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) CUTICULAR/ INTEGUMENTAL MODIFICATIONS: Cuticular modification Cuticular Cuticular out growths invagination Cuticular Setae Apodemes appendages Spurs Apophyses Cuticular Aculei processes Spines A. Cuticular out growths:  They are divided into cuticular appendages and cuticular processes depending on the presence or absence of membranous articulations. I. Cuticular appendages:  These are the outgrowths of the cuticle / integument connected with it by means of a membranous joint. They arise from modified epidermal cells. These are classified in to setae and spurs. (1) Seta/ Macrotrichia: ♣ Commonly known as hairs and arise from a cup like alveolus or pit. Setae are hollow structures developed as extension of exocuticle and are produced by a single enlarged hypodermal cell called ‘ trichogen’ cell. Articular membrane is usually produced by a second hypodermal cell called ‘tormogen’ cell. ♣ Setae have role of taxonomic importance and vary with species to species. Study of arrangement of setae is known as ‘chaetotaxy’. (2) Spurs: ♣ Occur on the legs of many insects and differ from setae in beingmulticellular in origin. II. Cuticular processes:  They have no membranous articulation; They are of two types (1) Microtrichia / fixed hairs / aculei: ♣ These are minute hair like structures found on wings of Mecoptera and certain Diptera. (2) Spines: ♣ Outgrowths of the cuticle which are more or less thorn like in form. 12 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Sr. Spurs Spines No. 1 Cuticular appendages Cuticular processes 2 Movable, multicellular structures and thick These are immovable outgrowths of cuticle walled 3 E.g.: present on tibia of plant hoppers and honey E.g.: hind tibia of grasshopper and leaf bees hoppers B. Cuticular invagination:  The body wall or cuticle of the body wall invaginate internally and grow in to definite structures which are of two types. ♠ Apodemes- Hollow cuticular invaginations whichprovide area for muscle attachment ♠ Apophyses- Solid invaginations of the cuticle which gives mechanical support to various organs by forming distinct skeletal structures. MOULTING PROCESS  Process of periodical shedding of old cuticle and formation of new cuticle this process is known as moulting. Itis a complex process which involves: - Apolysis, Ecdysis and Sclerotization.  Apolysis : [Apo = formation ; Lysis = dissolution]  The dissolution of old cuticle and formation of new one is known as apolysis.  It starts with repeated mitotic division of epidermal cells resulting in increase in number and size of epidermis, Because of this change, the epidermal cells exert tension on cuticular surface and as a result get separated them from the cuticle.  Due to separation of epidermis from the cuticle a sub cuticular space is created and the epidermal cells starts producing their secretion i.e. moulting fluid and cuticular material into this space.  Ecdysis :  The stage where the insect has both newly formed epi and procuticle.  The ecdysial membrane starts splitting along the line of weakness due to muscular activity of the inner developing insect and also because of swallowing of air & water resulting in the distention of the gut and also due to the pumping of blood from abdomen to thorax through muscular activity.  After the breakage of old cuticles, the new instar comes out bringing its head followed by thorax, abdomen and appendages.  Sclerotization :  After shedding of old cuticle the new cuticle which is soft, milky white coloured becomes dark and hard through the process known as tanning (or) sclerotization.  Three types of hormones involved in the process of moulting which are as follows-  JH: Juvenile Hormone: Produced from corpora allata of brain that helps the insects to be in immature stage.  MH: Moulting hormone: Produced from prothoracic glands of brain that induces the process of moulting.  Eclosion Hormone: Released from neurosecretory cells in the brain that help in the process of ecdysis or eclosion. 13 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) BODY SEGMENTATION OF INSECT  Cockroach, Periplanata americana is a typical insect as it possesses all important characters of class insect.  In general, insect body is divided in to a series of rings or segments are known as “somites” or “metameres”.  During the process ofevolution, these somites get fused with each other in different ways forming the body parts of the existing arthropods.  The type of arrangement of these body segments in embryonic stage is known as primary segmentation while in adult insects is known as the secondary segmentation.  Insect body is divided in to three regions or tagmata namely head, thorax and abdomen. This grouping of body segments in to regions is known as tagmosis.  Head consists of 6 segmentspossessesmouthparts, compound eyes, simple eyes (ocelli) and a pair of antennae.  Thorax consists of 3 segments i.e. prothorax, mesothorax and metathorax, Meso and metathorax are together known as pterothorax. All the three thoracic segments possess a pair of legs and meso and meta thorax possess one pair of wings.  Abdomen has 11 segments with genital appendages on 8th and 9th segments.  The insect body generally consists of 20 segments. Fig. General Organization of Insect Body 14 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) INSECT HEAD  It is the foremost part in insect body consisting of 6 segments that are fused to form a head capsule.  The head segments can be divided in to two regions i.e. procephalon and gnathocephalon (mouth).  Head is attached or articulated to the thorax through neck or cervix.  Head capsule is sclerotized and the head capsule excluding appendages formed by the fusion of several sclerites is known as cranium.  Inside the head, an endoskeletal structure called the tentoriumwhich give supports to the brain, and provides a rigid origin for muscles of the mandibles and other mouthparts.  Head is concerned with feeding and sensory perception. Segment Appendages I Pre antennary segment Procephalon Pair of compound eyes& three ocelli (Simple eyes) II Antennary segment Pair of Antennae III Intercalary segment Single labrum IV Mandibular segment Gnathocephalon Pair of Mandibles V Maxillary segment Pair of Maxillae VI Labialsegment Single Labium Types of head position: The orientation of head with respect to the rest of the body varies. According to the position or projection of mouth parts the head of the insect can be classified as; (a) Hypognathous (Hypo – Below: Gnathous – Jaw ) The head remain vertical and is at right angle to the long axis of the body and mouth parts are ventrally placed and projected downwards. This is also kwown as Orthopteroid type. Eg: Grass hopper, Cockroach. 15 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) CockroachGrass hopper (b) Prognathous : (Pro – infront: Gnathous – Jaw ) The head remains in the same axis to body and mouth parts are projected forward. This is also known as Coleopteroid type.Eg: beetles Beetles (c) Opisthognathous : (Opistho – behind: Gnathous Jaw ) It is same as prognathous but mouthparts are directed backward and held inbetween the fore legs..This is also kwown as Hemipteroid or Opisthorhynchous type.Eg: bugs 16 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Mosquito Red cotton bug SCLERITES AND SUTURES OF HEAD The head capsule is formed by the union of number of sclerites or cuticular plates or areas which are joined together by means of cuticular lines or ridges known as sutures or any of the large or small sclerotized/harden areas of the body wall. These sutures provide mechanical support to the cranial wall. Suture: The sclerites separated from each other by means of thin impressed line called suture.(Sometimes referred as a sulcus). General insect possess the following sclerites- 1. Labrum:It is small sclerite that forms the upper lip of the mouth cavity. It isfreely attached clypeus by means of clypolabral suture. 2.Clypeus:It is situated above the labrum, separated by fronto-clypeal suture & also separated from gena by clypogenal suture. 3.Frons: It is unpaired, facial part of the head capsule lying between the arms of epicranial suture. 4. Gena: It is the area extending from below the compound eyes to just above the mandibles. It is separated from frons by frontoganal suture and from clypeus clypogenal suture. 5. Epicraniun: It forms the upper part of the head extending from frons to the neck. 17 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 6. Vertex: It is the top portion of epicranium which lies behind the frons or the area between the two compound eyes. 7. Epicranial Suture: Starting from the dorsal portion of the epicranium is an inverted Y shape suture known as epicranial suture or ecdysial line. The head capsule breaks open along this line at the time of moulting. 8. Occiput: It is an inverted “U” shaped structure representing the area between the epicranium and post occiput. 9. Post occiput: It is the extreme posterior part of the insect head that remains before the neck region. 10. Occular sclerites: These are cuticular ring like structures present around each compound eye. 11. Antennal sclerites: These form the basis for the antennae and present around the scape. Anterior view or face view The common sutures present in head are: 1. Clypeolabral suture:It is the suture present between clypeus and labrum. 2. Clypeofrontal suture or epistomal suture: The suture present betweenclypeus and frons. 3. Epicranial suture: It is an inverted ‘Y’ shaped suture distributed above thefacial region extending up to the epicranial part of the head. It consists of two arms called frontal suture occupying the frons and stem called as coronal suture. This epicranial suture is also known as line of weakness or ecdysial suture because the exuvial membrane splits along this suture during the process of ecdysis. 4. Occipital suture: It is ‘U’ shaped or horseshoe shaped suture between epicranium and occiput. 18 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 5. Post occipital suture: It is the only real suture in insect head. Posterior end of the head is marked by the post occipital suture to which the sclerites are attached. As this suture separates the head from the neck, hence named as real suture. 6. Genal suture: It is the sutures present on the lateral side of the head i.e. gena. 7. Occular suture: It is circular suture present around each compound eye. 8. Antennal suture: It is a marginal depressed ring around the antennal socket. INSECT THORAX  It is the middle part of the body consisting of 3segmentssuch as prothorax, mesothorax and metathorax, each possessing a pair of legs and a pair of wings on meso and meta thoracic segment. Meso and meta thoracic segments bear a pair of wings each together known as pterothorax (Ptera = wings).  Thorax generally concerned with locomotion.  The body wall of a typical insect is divided into four regions;  The dorsal (Upper) region is called dorsum or tergum/notum.  |The ventral (Lower) region is called as venter or sternum.  The two lateral regions are known as pleurae/pleuron.  Sclerites–The cuticle hardens at localized areas form sclerites. 19 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  Sutures – The sclerites are separated from each other by means of thin impressesd lines called as sutures.  Sclerites forming these regions are called as tergites, sternites and pleurites, respectively.  Sclerites of thoracic segments:- 1. Sclerites of tergum (tergites) - The dorsal sclerites consists of three segmental plates (nota) called pro-notum, meso-notum and meta-notum. Each notum is again divided into three parts i.e pre-scutum, scutum and scutellum. 2. Sclerites of pleuron (pleurites) –it is fully developed in winged insects. It is divided into two parts, anterior episternum and posterior epimeron. It is absent in prothorax. 3. Sclerites of sternum (sternites)–It is divided into eusternum and spinasternum. INSECT ABDOMEN  The abdomen in the embryo usually consists 11 segments.  The abdominal segments are sometimes designated as uromeres.  The terminal region of abdomen is called telson which bears anus.  The 1st abdominal segment gets fused to metathorax forming propodeum. (In ants, bees and wasps).  The first eight abdominal segments carry a pair of spiracles each.  Thorax generally concerned with reproduction and metabolic activity.  Appendages of abdomen– 1. Non reproductive appendages – a) Cerci –They are present on 11th segment in most of the insects. It is present inmale cockroach, silverfish, grasshopperCerciusuallyact as tactile organ or sound receptors in grasshopper. They become a part of male genitalia in caddis fly. In earwigs, cerci are modified into defensive organ. b) Prolegs in insect larvae- The larvae of Lepidoptera bear five pairs of abdominal legs called Prolegs on 3rd 4th 5th 6th and 10th segments. These Prolegs bear spines like structures called crochets, on terminal ends to grip the plant surfaces. In case of larvae of sawfly there are eight pairs of Prolegs but are without crochets. c) Abdominal gills- It is present in aquatic insects for respiration. eg. Nymph of odonata. d) Cornicles: Aphids have a pair of short tubes known as cornicles or siphonculi projecting from dorsum of fifth or sixth abdominal segment. 20 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) They permit the escape of waxy fluid which perhaps serves for protection against predators. 2. Reproductive appendages –  It includes abdominal Segments from 1 to 7 are pregenital segments, 8th and 9th are known as genital segments as they form genital appendages i.e. ovipositor in females and aedeagus or penis in males. 10thand11thsegments are known as postgenital segments. These organs are specially concern with mating in male and deposition of eggs in females. They are collectively called as external genitalia or gonapophysis.  Male external genitalia-The9th sternum bears two styli and pair of claspers which help to hold female during copulation. The aedeagus lies between claspers.  Female external genitalia-It has a special egg laying organs called ovipositor for egg lying on 8th and 9th segments.The ovipositor of house fly& fruit fly is called pseudoovipositor. INSECT ANTENNAE  Antennae are a pair of sensory preoral appendages arising from the 2nd or antennal segment of the head possessing nerves coming from deutocerebrum of the brain.  Antennae are also called feelers.  They are well developed in adults and poorly developed in immature stages.  Antennae are absent in order protura and class Arachnida whereas 2 pairs of antenna (antennules) are present in class Crustacea.  Aantennal socket (antennifer) is provided with an antennal suture. The base of socket is connected to the edge of the socket by an articulatory membrane. This permits free movement of antennae 21 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  Antenna consists of 3 parts:- 1) Scape: It is the first segment of antenna. It articulates with the head capsule through antennifer which provides movement for the scape. 2) Pedicel: It is the 2nd or middle segment of antenna that forms a joint between scape and flagellum. It consists of the special auditory organ known as “Jhonston’s organ”. 3) Flagellum: It is the last antennal segment which consists of many segments that varies in shape and size. Types of Insect antennae SrN Type of antennae Example o. 1 Filiform (Thread like) Grasshopper 2 Setaceous(Whip/ bristle like) Cockroach 3 Moniliform (Like string of beads) Termites& Thrips 4 Pectinate (Comb like) Female mulberry silk moth 5 Bipectinate (Double comb) Male mulberry silk moth 22 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 6 Serrate(Saw like) Pulse beetle, Mango stem borer 7 Clavate (Clubbed) Butterflies, Moths 8 Clavate with hook Skipper butterflies 9 Capitate (Clubbed with knob) Red flour beetle 10 Geniculate (Elbowed) Ants, honey bees, Wasps 11 Lamellate (plate like) Rhinoceros beetles, dung rollers,chaffer beetles 12 Plumose(Feather like) Male Culex mosquito, stylopids 13 Pilose (brush like hairs) Female Culex mosquito 14 Aristate (antennae with arista) House fly 15 Stylate (antennae with style) Jassids, Robber fly Term Mean 1. Gustatory Related with stimulus of taste 2. Olfactory Related with stimulus of smell 3. Tactile Related with stimulus of touch 23 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Functions of Antennae 1. To feel and find the its way 2. To detect danger 3. To find food 4. To find the opposite sex 5. To communicate with each other e.g. (Ants) 6. To smell – bears olfactory organ e.g. (House fly) 7. To perceive the sound Chorodontonal organe.g. (male mosquito) 8. To serve secondary sexual characters 9. It possesses hydro fuse hairs to form air funnel eg. (Water beetle) 10. Taste hairs occur on antennae e.g. (Cockroach) 11. Helps in mating by holding opposite sex eg. (Flea, Spring tails) 12. Useful for clasping the female during copulation 24 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) STUDY OF INSECTS MOUTH PARTS Typical mouthpart of an insect consists of the following parts. (i) Labrum (upper lip) (ii) A pair of mandibles (upper Jaw) (iii) A pair of maxillae (lower Jaw) (iv)Labium (lower lip) (v) Hypopharynx (tongue)  The mouth parts of insects can be basically grouped in to following types based on the type of food and method of feeding. Type of Mouth parts Sr. Type of Mouth parts Examples No. I (Mandibulate type) Those insects feeding on solid food material. 1. Chewing and Biting type Grasshoppers, cockroachesBeetles, Lepidopterous larvae. II Sucking type / Haustellate type Those insects feeding on liquid food material. 1.Piercing and sucking type Plant Bugs and Mosquitoes 2.Rasping and sucking type Thrips 3.Sponging type Adult Houseflies 4.Chewing and lapping type Honey bees 5.Siphoning type Butterflies and moths III Other types 1. Mask type Naids of Dragonflies 2. Degenerate type Maggots of Diptera 25 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) MANDIBULATE TYPE OF MOUTH PARTS  Those insects feeding on solid food material such as leaves, fruits, tree bark. I) CHEWING AND BITING TYPE OF MOUTH PARTS E.g. Grass hopper, Cockroach, Beetles, Lepidopterous larvae (a) Labrum:  It is a single unpaired that forms the upper lip of the mouth cavity.  It protects the mandibles and helps in closing of the mouth cavity and guides the food in to mouth or hold the food material while feeding.  Labrum hangs down from the clypeus through a clypeo-labral suture.  The inner surface of labrum is lined by small lobe like epipharynx, which is the taste organ. (b) Mandibles:  These are the paired, unsegmented, and strongest and sclerotized structures calledfirst pair of jaws.  They are attached to the head capsule by means of two joints known as ginglymus and condyle.  They possess teeth like molars and incisors that help in the process of cutting the food material.  Each mandible is moved by powerful Abductor and adductor muscles. 26 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) (c) Maxillae:  These are paired and also known as second pair of jaws.  These are homologous structures with basal triangular ‘cardo’, middle rectangular ‘stipes’ and the lateral ‘palpifer’ bearing maxillary palpi and lobe like inner ‘lacinia’ and outer ‘galea’. Maxillary palps possess olfactory and gustatory sense receptors and function as sensory organs. These Galea and lacinia helps in holding the food material along with the mandibles. (d) Labium:  It is known as lower lip and is also called as second maxillae. It closes the mouth cavity from below.  It is divided in to proximal prementum. centralmentum and distal submentumPrementum has three terminal lobes.  Near the base of pre mentum, on either side lobe like ‘palpiger’ is present which bears labial palps. The median pair is ‘glossae’ and outer ‘paraglossae’ together called ligula that function mainly as gustatory sense organs. (e) Hypopharynx:  It is a tongue like structure situated between labrum and labium and ducts of salivary glands open on or near its base. The function of hypopharynx is to mix saliva with the food material. HAUSTELLATE TYPE OF MOUTH PARTS  Those insects feed on liquid food material such plant sap, fruit juice, blood etc 1. PIERCING AND SUCKING TYPEOF MOUTH PARTS  e.g.: plant bugs, mosquitoes  They are mainly adopted for piercing the tissues and sucking either plant sap or the nectar or blood from the host. 27 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) a) Labrum :  Labrum is modified into a small flap like structure at the base of rostrum. b) Mandibles & maxillae:  Mandibles and maxillae are modified in to sharp needle like stylets. (Four in numbers)  The mandibular stylets form the outer pair and possess serrated margins at their tip.  The maxillary stylets forms the inner pair having smooth curved tips and combining together enclosing a food channel.  The food channel is divided in to an upper cibarium and lower salivarium with the help of the grooves present inside the maxillary stylets. Salivarium is used for releasing the saliva and cibarium is used for sucking the sap. c) Labium :  Mouth parts are represented by rostrum/beak/Proboscis which is a modification of Labium.  It acts as a pouch for protecting the mandibular and maxillary stylets.  Rostrum has sensory hairs at its tip for sampling the food and locating spot for piercing. d) Hypopharynx :  The hypopharynx is modified in to a pharyngeal pump and is situated at the tip of the food channel.  Feeding Mechanism:  At rest proboscis is always held parallel to ventral side of insect body.  During feeding the rostrum shot out, stylets released and rostrum looped behind to allow the stylets to penetrate plant tissues.  Mandibular stylets by their sliding movement puncture a hole in plant tissues. Then maxillary stylets are pushed inside.  Saliva is injected through salivary channel to dilute the cell sap, dissolve the cell wall.  Then suck the contents (sap/ blood / nectar) through cibarium with the action of pharyngeal and cibarial muscles. 2. RASPING AND SUCKING TYPE OF MOUTH PARTS E.g. Thrips  Insect like thrips lacerate the epidermis of plant parts and suck the oozing cell sap.  These are called asymmetrical type, since right mandible is rudimentary or reduce or absent whereas the left mandible is modified in to a mandibular stylet hence left mandible is present.  Maxillae are modified in to maxillary stylets which are mainly useful for sucking the sap that is released outside due to the rasping of tissues by the left mandible. 28 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 3. SPONGING TYPE OF MOUTH PARTS: - e.g.: housefly a) Labrum:  It is represented by labrum epipharynx.  It forms stylet.  It is born on anterior face of haustellum. b) Mandibles:They are entirely absent. c) Maxillae:They are represented by a pair of maxillary palps.Maxillary palpi are 1-3 segmented d) Labium :  These mouthparts are represented by proboscis formed from the labium.  The proboscis is divided into a basal rostrum, middle haustellum and adistallabellum.  The labellum is a sponge like structure. It is traversed by a number of narrow transverse channels called pseudotrachea which converge at one point in the centre of the labellum. From this point, the food enters in to food channel which is formed by the labrum- epipharynx and hypopharynx. e) Hypopharynx :  It is also modified into stylet like structure and is present on haustellum.  Feeding Mechanism:  During feeding, the proboscis is pressed over the food material.  The pseudo trachea gets filled with the food material by the capillary action which converges at one point in the centre of the labellum.  From this point, the food enter in to food channel which is formed by the labrum- epipharynx and hypopharynx and is sucked up from the central point in to the oesophagus. 29 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 4. CHEWING AND LAPPING TYPE OF MOUTH PARTS:e.g.: honey bees  The labrum and mandibles are biting type whereas maxillae, labium and hypopharynx combine together to form a sucking proboscis. a) Labrum:It is narrow plate attached to clypeus. b) Mandibles:The mandibles are dumbbell shaped, used for molding wax and squeezing the nectar. c) Maxillae :  Both maxillae are modified and suspended from head.  They are articulated through like cardo to which is attached stipes.  The maxillary palpi are very small or reduced and it is peg like structure articulating with stipes.  The cardo of maxillae unite with submentum of labium forming an inverted “V” shaped lorum.  Galea and lacinia attached at the lorum. d) Labium :It is also called as proboscis and consist of following parts;  Submentum (lorum),mentum, prementum, labial palp and glossa.  Glossae are provided with long hairs and a small spoon shaped lobe, called flabellum or bouton at its apex.  Two paraglossa are cup like structure situated at the base of glossa. e) Hypopharynx:It is vestigial or reduces.  Feeding Mechanism:  When at rest the mouthparts are folded down beneath the head.  During feeding they become straight and shot out glossae and lick the nectar with the help of flabellum.  The glossal toung thus smeared with nectar is rapidly retracted between labial palp and galeae.  As a result the nectar is squeezed off and deposited in a small cavity formed by paraglossae and sucked in by the capillary action of pharyngeal pump. 30 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 5. SIPHONING TYPE OF MOUTH PARTS: e.g.: Moths and Butterflies.  These are specially modified for taking nectar from the flowers.  The galea of maxilla form into a slender, hollow, tubular structure which remains as an elongated coiled proboscis underneath the head during non feeding.  Mandibles are totally absent.  The labrum and maxilla palpi are reduced.  Labium is modified in to a small basal plate possessing 3 segmented labial palps.  The food channel is formed by the fusion of both the galeae.  The nectar will be sucked from the flowers through muscular action 31 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) STUDY OF INSECT LEG  Insect legs are paired; hollow more or less cylindrical and jointed outgrowth of thoracic segments. They are the important locomotory organ. Components of Insect Leg Fig. Structure of Typical Insect Leg Insect leg mainly consists of 5 parts viz. 1. Coxa: It is the functional basal segment and it is rigidly fixed to thorax. 2. Trochanter: It is very small and the second segment. It is articulated with coxa and fixed to femur. 3. Femur: It is the largest, strongest segment and is articulated with the tibia.. 4. Tibia: It is equal or more than the length of the femur, articulated with tarsus. 5. Tarsus: it is the largest segment of the leg and usually devided into sub segments tarsomeres. The number of tarsomeres vary from 1-5. The tarsus at its end consists of pretarsus which is in the form of a pair of claws and cushion like pulvilli. In between the claws, if there is lobe like structure, it is known as “arolium” as in Orthoptera (grass hopper) and if it is bristle like structure, it is called “embodium” as in Diptera.  Legs of Larvae: Prolegs  Thoracic legs mean true legs and abdominal legs mean Pseudo legsor false leg of larvae.There are two to five pairs.  Abdominal legs are thick, fleshy and unsegmented and the tip (Planta) bear hooks called crochets, which help in cling the plant surface. 32 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) MODIFICATIONS OF LEGS IN DIFFERENT INSECTS Type Legs modified Example purpose Cursorial All legs Blister beetle, wasp Walking Ambulatorial All legs Cockroach Running Saltatorial Hind legs Grasshopper , gryllids Leaping and jumping Fossorial Front legs Mole crickets, dung rollers Digging Raptorial Front legs Preying mantids Preying (grasping ) Natatorial Hind legs Water beetle, water bugs Swimming Scansorial All legs Head louse clinging Prehensile All legs Dragon flies Catching prey, basketForming type Antennal Front legs Honey bee For cleaningantennae cleaning legs Pollen basket Hind legs Honey bee For collectingpollen and brush type and cleaning the body Fig. Modification of insect legs 33 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) STUDY OF INSECT WINGS  Based on the presence or absence of wings, class insecta is divided into two subclasses; 1. Apterygota &2. Pterygota o The primitive apterygotes are wingless. E.g.: Silver fish and spring tails. o Secondarily wingless insects: Among pterygotes, some insects in their advanced stage of growth (Adult) shed the wings e.g. Bed bugs, head louse.  Based on the degree of development of wings the insects may be classified into three forms; 1) Macropterous, 2) Brachypterous & 3) Apterous.  The insect wings may sometimes possess some pigmented spot near coastal margin known as pterostigma or stigma as in Odonata (dragon flies and damsel flies). Fig. Insect wing areas  A typical insect wing is triangular with three margins and three angles.  The anterior margin strengthened by the costa is called coastal margin and the lateral margin is called apical margin and the posterior margin is called anal margin  Three angles are,  Humeral angle: between body wall and costal margin  Apical or outer angle: between costal and apical margin  Anal angle or tornus : between apical and anal margin  Wings area are;  The surface area of typical insect wing is divided in to two portionsi.e.Remegium and Vannal Area.  The anterior (upper) part of the wing towards coastal margin where more no of longitudinal veins are present is called remigium.  The posterior part of the wing where veins are sparsely distributed is known as Vannal Area, which is called as clavus in forewings and vanus in hindwings.  Jugum is the inner most portion of the wing that is cutoff from the main wing by jugal fold.  Wings are very thin broad leaf like structures strengthened by a number of hollow narrow tubular structures called veins. 34 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  Arrangement of veins on wing surface is known as Wing venation, which consists of two types of veins; 1. Longitudinal veins: Extend from base of the wing to the margin. They may be convex (∩) or concave (U) 2. Cross veins: That interlinks the longitudinal veins. Fig. Hypothetical wing venation Longitudinal veins: 1. Costa (C): It forms the thickened anterior margin of the wing (costal) and isun-branched and is convex 2. Sub costa (Sc): It runs immediately below the costa always in the bottom ofa trough between C and R. The two branches of SC are Sc1 and Sc2 and is concave 3. Radial vein (R): It is the next main vein, it divided in to two branches R1 and Rs (Radial sector). R1 goes directly towards apical margin and is convex; Rs is concave and divided in to 4branches, R2, R3, R4, and R5. 4. Media (M) It is divided in two branches 1. Media anterior (MA) which is convex and2. Media posterior (MP) and is concave. Media anterior is again divided into MA1 and MA2. Median posterior is again divided in to MP1, MP2, MP3, and MP4. 5. Cubitus (Cu): Cubitus is divided into convex CU1 and concave CU2. CU1 is again divided into CU1a and CU1b. 6. Anal veins (A):These veins are convex. They are individual un-branched, 1-3 in number.1 or 2 jugal veins (unbranched) are present in the jugal lobe of the forewing 35 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Cross veins: - Small veins often found inter connecting the longitudinal veins are called cross veins.  Humeral cross vein (h):between costa and subcosta.  Radial cross vein (r): between radius and radial sector.  Sectorial cross veins (s): between sub branches of radial sector.  Radio medial cross vein (r-m): between radius and media.  Medical cross veins: between branches of media.  Medio-cubital veins: between media and cubitus. DIFFERENT TYPES OF WINGS 1. Tegmina:Forewings are leathery and tough. They are protective in function. They protect the membranous hindwings. They are not used for flight.e.g.: forewings wings of cockroach, grasshopper 2.Elytra: The wing is heavily sclerotised without clear venation. Wing is tough and it is protective in function. They protect the membranous hind wings and abdomen. e.g.: Forewings beetles and weevils. 3.Hemelytra: The base of the wing is thick like elytra and the remaining half is membranous. They are not involved in flight and are protective in function. e.g.: Forewings of bugs. 4.Membranous: Naked thin with clear venation. e.g.: Both the wings of Dragonflies, bees and wasps, Hind wings of grasshopper, beetles,cockroach, both fore wings and hind wings of (wasp, bees, dragonfly and damselfly). 5. Scaly wings: Wings thin, membranous but covered with unicellular scales all over the surface. Scales are responsible for colour. e.g.: Both the wings of moths and butterflies. 6. Fringed wings: Wings are highly reduced with reduced venation. The wings are fringed with long marginal hairs giving a feather like appearance e.g. both the wings of thrips 7. Fissured wings: Forewings are longitudinally divided twice forming a fork like structure whereas hindwings are divided twice in to three arms. All the forks possess small marginal hairs.e.g.: Both the wings of plume moth 8. Halteres: In houseflies the hind wings are modified into small microscopic structures/ knobbed vibrating organs called haltere.They are divided in to three regions namely scabellum, pedicel and capitellum. They act as balancers. E.g. Hind wings housefly and front wings, male stylopids, mosquito and male scale insect. 9. Pseudohalteres: They are short and modified in to pseudohalteres which are dumbbell shaped. Eg: Front wings of Strepsiptera 36 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) ElytraHemelytraMembranous wings Fringed wingsFissured wings Halteres Tegmina wings Scaly wings 37 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) WING COUPLING APPARATUS/ORGANS/MECHNISMS  Among the insects with two pairs of wings, the wings may work separately as in the dragonflies and damselflies.  For taking flight, insect need to keep both the fore and hind wings together as a single unit. The structures in the form of lobes, bristles, hairs or spines that help the wings to be together are known as wing coupling organs. 1. Jugate type or jugum type: The costal margin of the front wing possess a small lobe at the base called fibula which rest on the surface of the hind wing or sometimes engages with spines present on the upper surface of hind wings. e.g.: primitive lepidopterans of the family Hepialidae. 2. Frenulum/Franate/retinaculum type: The hind wings possess bristle or spine like structure or group of hairs known as frenulum.The forewings possess hook like retinaculum on anal side. During flight the frenulum passes beneath the retinaculum and thus the both the wings are kept together. e.g.: Fruit sucking moth. 3. Amplexiform: Costal margin of hind wing and anal margin of forewing overlap one above the other e.g.: butterfly 4. Hamuli/Hamulate : TheSmall curved hook like structures present on the costal margin of the hind wing known as Hamuli that fit into the upward fold of the anal margin of the forewings.e.g.hymenopterans (wasps and bees) Jugate typeFrenulum type Amplexiform type Hamuli type 38 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) SENSORY AND SOUND PRODUCING ORGANS The sense organs in an insect body are distributed on different parts and respond to a given stimulus such as light, sound, touch, chemicals etc. The sense organs may be classified as; 1. Photoreceptors(or) Visual organs- To detect light energy. 2. Auditory receptors (or) organs of hearing- To detect sound waves. 3. Chemoreceptor’s which respond to chemicals- To detect smell and taste. 4. Mechanoreceptor/Tactile receptors which respond to touch- To detect mechanical force 5. Thermoreceptor – To detect heat. 1. Visual organs or photoreceptors:These are two types, Compound eyes and Simple eyes. I. Compound eyes:These organs possess the ability to perceive light energy and able to produce a nerve impulse. The compound eyes may be completely absent in insects like Protura or they may remain reduced in endoparasitic Hymenoptera. The compound eyes are present on either side of the head capsule of an adult insect and also in the nymphs of Exopterygota. These are a pair and consist of number of individual units (or) facets called ommatidia. Function is to gather light. Classification of Compound eyes based on image formation;  Apposition eyes:These are active during day time (diurnal insects);e.g.: butterflies  Superposition eyes:These are active during evening and night time (Nocturnal insects); e.g.: moths II. Simple eyes (or) ocelli:These are of two types  Dorsal ocelli:Seen in nymphs and adults of Hemimetabolous insects and adults of Holometabola.Dorsal ocelli are represented by fenestrae in cockroach. It perceive light to maintain diurnal rhythm.  Lateral ocelli:Also known as stemmata. These are present on the lateral sides of the head of Endopterygote larva. It helps to detect form, colour and movement. 2. Auditory organs (or) organs of hearing: Insects are provided with structures (or) organs that are able to perceive the sound waves (or) the aquatic water currents. Among the organs of hearing, the auditory hairs, tympanal organ and Jhonston’s organ are important. 39 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  Auditory hairs : These are present on the body of insects such as larvae of Lepidoptera which are developed from the modified epidermal cells. These respond to the sounds of air (or) water currents mediated by the hair sensillae (or) trichoid  Tympanal organ : Tympanum is present one on either side of the 1st abdominal segment of short horned grasshoppers, on the base of foretibia in long horned grasshoppers and crickets, and on thorax or abdomen in Lepidoptera.  Jhonston’s organ: It is present on the pedicel of antennae and functions asan auditory organ responding to air (or) water currents. They are absent in Collembola.  Pilifer of hawk moths (sphingid moths): A unique auditory organ, sensitive to ultrasonic frequencies is found in the head of several species of Sphingidae. 3.Mechanoreceptor: (detect mechanical force)  Trichoid sensilla:Hair like sense organ. Sense cell associated with spur and seta. These cells are sensitive to touch and are located in antenna and mouthparts.  Campaniform / Dome sensilla:These cells are sensitive to pressure and located in legs joints and wing bases.  Chordotonal organ:The specialized sensory organs that receive vibration are subcuticular mechanoreceptors called chordotonal organ. 4.Chemoreceptors: (detect smell and taste): It contains sensilla with one pore (uniporous) or more pores (multiporous). ♣ Uniporous chemoreceptors mostly detect chemicals of solid and liquid form by contact called gustatory receptorsand located in antennae. ♣ Multiporous chemoreceptor’s detect chemicals in vapour form at distant by smell called olfactory receptors and located in mouth and tarsi. 5. Thermoreceptor – (detect heat) Present in poikilothermic insects and sensitive to temperature changes. E.g. Bed bugs. 40 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) METAMORPHOSIS  Metamorphosis is derived from Greek word ‘Meta’ = Change, ‘morph’ = form or structure.  Series of changes that takes place during the development of an insect from egg to adult are collectively known as metamorphosis.  Metamorphosis include three developmental processes namely, growth, differentiation and reproduction which takes place in larval, pupal and adult stages respectively. o Eclosion: The process of hatching of eggs after fully development of embryo called eclosion. o Instar: It is the forms of the body during two inter moults. The larva is known as first instar, immediately after hatching from egg, and as second instar after first moult and so on o Stadium: The interval or time period between two moults is known as stadium. o Exuviae: The skin shed during moulting process is known as exuviae. o Imago (or) Adult: It is the final stage of insect with well-developed organs for reproduction, which emerges out from pupal body. o Sub-imago: It is a pre adult stage with fully developed wings but without reproductive organs.E.g.: mayflies (Ephemeroptera) Types of metamorphosis: 1. Ametamorphosis (Ametabolous) 2. Incomplete metamorphosis (Hemimetabolous) 3.Gradual metamorphosis: (Paurometabola) 4. Complete metamorphosis/Holometabolous 5. Hyper metamorphosis 1. Ametamorphosis: ♠ E.g.: Apterygote e.g.: silver fish, springtails. ♠ Insects do not undergo any metamorphosis. ♠ These insects have only three stages in their life namely egg, young ones and adult. ♠ The hatching insect resembles the adult in all respects except for the size and called as juveniles. ♠ Moulting continues throughout the life 41 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 2. Hemimetabola: (Incomplete metamorphosis) ♠ E.g. Dragonfly, damselfly and may fly. ♠ These insects also have three stages in their life namely egg, naiads and adult. Pupal stage is absent. ♠ The young ones are aquatic and are called as naiads. ♠ They are different from adults in habit and habitat. ♠ They breathe by means of tracheal gills. ♠ In dragonfly naiad the lower lip (labium) is called mask which is hinged and provided with hooks for capturing prey. After final moult, the insects have fully developed wings suited for aerial life. 3. Paurometabola: (Gradual metamorphosis)- ♠ E. g. grasshoppers, cockroaches, termites, true bugs, cicadas, and hoppers. ♠ It is also called as simple metamorphosis. ♠ The life cycle includes egg, nymph and adult stages. ♠ The nymph resembles the adult in all the characters except wings. Nymphs possess wing buds which transform in to fully developed wings in adult stage. ♠ Both nymphs and adults share the same habitat. ♠ In these insects, wings develop externally and hence are also called as Exopterygota. ♠ Pupal stage is absent hence, development is said to be direct and simple. 4. Complete or Holometamorphosis or indirect development: ♠ E.g. Butterfly, moth, Beetles, weevils, fly and bees. ♠ The life cycle includes four stages; egg, larva, pupa and adult. ♠ Larvae of butterflies are called caterpillar. ♠ Larva differs from the adult both in body structure and habits. Larva has both thoracic and abdominal legs, sometimes legs may be absent in larva, whereas adult has only thoracic legs. ♠ Compound eyes are absent in larva. ♠ Larva undergoes moulting to enter in to pupal stage from which the adult insect emerges. ♠ Wings develop internally during the pupal stage and hence, they are called Endoptreygotes. 42 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) 5. Hypermetamorphosis: ♠ This is a peculiar type of development which consists of two or more types or forms of larvae in the life cycle of insects. ♠ In majority of the cases the first larval, instar is campodeiform and the subsequent larval forms depends on type and mode of life of the larva. E.g.: In blister beetle (Meloidae; Coleoptera), the first larval instar is campodeiform followed by scarabeiform larval type. SIGNIFICANCE OF METAMORPHOSIS i. It helps the insect to tide over unfavorable climate conditions by entering into hibernation, aestivation and or diapauses. ii. It helps the insect to accommodate growth by periodical shedding of their old cuticle and by formation of new cuticle. iii. It helps the insect to reduce or avoid competition for food amongst themselves by either entering into inactive stage or by acquiring different feeding habits and habitats. iv. It helps the insect as a protective adaptation by a way of mimicry. i.e. resembles to the nature. v. It also serves as an important aspect in classification of insects. SEASONAL ADOPTIONS  Diapause : -  It is the period of arrested growth or development in the life cycle of the insects during which the physiological processes like differentiation and reproduction are suspended. Diapause is represented by low rate of metabolism, low O2 consumption, low body weight, low body water content and vitamin deficiency in the blood. Diapause may occur in egg, larva, nymph, pupa or adult stage.  The occurrence of diapause during summer due to high temperatures is known as “aestivation”  Whereas the period of inactivity during winter due to low temperatures known as “hibernation”. 43 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) IMMATURE STAGES OF INSECTS  Immature stages of exopterygote insects are known as Nymphs and endopterygote insects are known as Larvae. Differences between Larva and Nymph Sr.No. Larva Nymph 1. It is an immature stage, of Endopterygotes. Immature stage of exopterygotes 2. It undergoes holometamorphosis It undergoes hemimetamorphosis 3. Body is vermiform which differs from the adult Body resembles the adult in all the both in structure and feeding habits characters except wings 4. Consists of ocelli and reduced Antennae Have compound eyes and antennae 5. Possess both thoracic and abdominal legs Possess only thoracic legs. 6. The larva is different from adult in feeding habits Nymph resembles the adult in feeding and behaviour habits and behaviour 7. The larva enters pupal stage No pupal stage 8. E.g.: Lepidoptera, Coleoptera Hemiptera, Orthoptera. TYPES OF LARVA 1. Protopod larva: E.g.: Endoparasitic Hymenoptera. The larvae are partially developed. They possess well developed head and thoracic segments but lack segmentation in the abdomen. They possess rudimentary cephalic and thoracic appendages but no abdominal appendages. They have partially developed digestive system and underdeveloped respiratory and nervous systems. 2. Oligopod larva: Thoracic legs are well developed. Abdominal legs are absent. These are classified in to two types’ viz., campodeiform and scarabaeiform. 44 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Differences between Campodeiform and Scarabaeiform Sr. Campodeiform Scarabaeiform No. 1 The body is long and fusiform in shape Body is ‘C’ shaped 2 Body is dorso-ventrally compressed with Body is cylindrical or sub cylindrical, sclerotized cuticle stout and fleshy in nature 3 Prognathous type of head Hypognathous type of head 4 Long thoracic legs Short thoracic legs 5 Apair ofterminalabdominal processes (anal Absent cerci) are present 6 These are active Inactive 7 Predatory in nature Phytophagous 8 e.g. grub of antlion /grub of lady bird beetle. e.g.: grub of rhinoceros beetle/white grub 3. Polypod larva (Eruciform larva): The larva possess well defined segmentation of the body with three pairs of thoracic legs, 2-5 pairs of abdominal legs (3rd, 4th, 5th, 6th and 10th abdominal segment. They are phytophagous and destructive. Different types of polypod larvae: A. Hairy caterpillar larval body is fully covered with hairsE.g.: Red hairy caterpillar, Castor hairy caterpillar B. Sphingid caterpillar / larva the larva consists of a horn (or) hook on the dorsal surface of 8th abdominal segment. E.g.: Gingelly death’s head moth C. Looper: Only two pairs of abdominal legs present on 6th and last abdominal segment during walking the insect body forms a complete loop like structure hence, the name looper.E.g.: Mango looper. D. Semilooper: e.g.: Castor semilooper First two pairs of abdominal legs (on 3 rd and 4 th segments) are reduced, hence a part of the insect body forms a small loop during its movementE.g.:Castor semilooper. 4. Apodous larva: These are characterized by the absence of trunk appendages (or) legs. They possess 3 pairs of sensory papillae in the place of thoracic legs. They are usually derived from Oligopod type.Based on the degree of development of the head capsule and its appendages, these larvas are divided in to 3 types. 45 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) a. Eucephalous: e.g.: Sub order Nematocera of Diptera, Mosquito(Culcidae) The larva consists of a well sclerotized head capsule. b.Hemicephalous. e.g.: Brachycera of Diptera, robberflies (Asilidae) Larva possess partially developed head capsule c. Acephalous e.g.: Cyclorrhapa of Diptera, Muscidae (houseflies)the larva are characterized by the absence of head capsule and mouth parts are represented by mouth hooks. Appearance Larval Type Common Description Examples Name Body cylindrical with short thoracic legs Moths Eruciform Caterpillar and 2-10 pairs of and fleshy abdominal butterflies prolegs Elongated, flattened body with prominent Lady Campodeiform Crawler antennae and/or beetle, cerci. Thoracic legs lacewing adapted for running Body robust and "C"- June shaped with no White beetle, Scarabaeiform abdominal prolegs grub dung and short thoracic beetle legs Body long, smooth, Click and cylindrical with beetle, Elateriform Wireworm hard exoskeleton and Flour very short thoracic beetle legs Body fleshy, worm- House fly, Vermiform Maggot like. No head capsule flesh fly or walking legs 46 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) TYPES OF PUPA It is resting, inactive stage of the holometabolous insects and transitional phase during which the wings are developed and the insect attain matured sexual organs. The pupa is incapable of feeding, locomotion except in some cases where they crawl (Neuroptera) (Aphid lion), e.g.: mosquitoes. Later it emerges as adult, pupation may be takes place either in soil, or on the plant surface or within the webs. Pupae are divided on the following bases; I. Based on the presence or absence of powerful mandibles Decticous pupae Adecticous pupae Possess relatively powerful mandibles which Do not possess the mandibles but with the are used for escaping of the adult from the help of other appendages, adults escape from cocoon i.e. to break the cocoon. e.g.: the cocoon e.g.: Lepidoptera, Diptera. Neuroptera II. Based on the attachment on the appendages (or) shape of the pupae 1. Exarate pupa: e.g.:Coleoptera The pupae have appendages which are free without any secondary attachment to the body 2. Obtect pupa eg: Lepidoptera (moths) The pupae have appendages which are firmly pressed against the body and the pupa is highly chitinized. 3. Coarctate: e.g.: Diptera (housefly) The pupa remains enclosed in a puparium formed by the last larval skin and the pupa looks like a capsule or barrel. 4. Chrysalis: eg: butterflies It is an obtect type of pupa which has golden colouration and a stalk. 47 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Appearance Pupal Common Description Examples Type Name Developing appendages (antennae, wings, legs, etc.) held tightly against Butterflies Obtect None the body by a shell-like and moths casing. Often found enclosed within a silken cocoon. All developing Beetles, Exarate None appendages free and Lacewings visible externally Body encased within the Coarctate Puparium hard exoskeleton of the housefly next-to-last larval instar It is an obtect type of pupa which has golden Chrysalis None butterflies colouration and a stalk. 48 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) STUDY OF INSECT DIGESTIVE SYSTEM  Digestive system of insect consists of Alimentary canal and Salivary glands.  Alimentary canal: It is a long, muscular and tubular structure. The alimentary canal in insects extends from mouth to anus which is divided in to three parts, foregut, midgut and hindgut. 1. Foregut (stomodaeum):  Ectodermal in origin.  Ectodermic Cells secretes cuticular layer called Intima.  It is the anterior part of the alimentary canal which starts with the mouth cavity and ends with the gizzard (or) proventriculus.  Terminal mouthparts lead into a preoralcavity. Preoralcavity between epipharynx and hypopharynx is called asCibarium. Preoralcavity between hypopharynx and salivary duct is Salivarium.  It is divided in to pharynx,esophagus, crop and gizzard. i. Pharynx: Behind the mouth a well musculated organ called Pharynx is present which pushes the food into esophagus. Pharynx also acts as a sucking pump in sap feeders. It is the region between the mouth and oesophagus.It concerned with ingestion and back word flow of food. ii. Esophagus: It is a narrow Simple tube of the foregut through which the foods get transported from pharynx into the crop. iii. Crop: It is a sac like structure which is a dilated form and mainly serves the purpose of storage of food material. In honey bees crop is called as honey stomach where nectar conversion occurs. iv. Gizzard (Proventriculus): It formsthe last portion of foregut. This consists of the cuticular intima layer modified in to teeth like denticles that help for grinding the food material.It is found in solid feeders and absent in fluidfeeders or sap feeders. 49 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik)  Stomodeal valve or cardiac valve:  After gizzard the foregut forms into a stomodeal valve or cardiac valve which is surrounded by gastric (or) hepatic caecae.  This prevents backward movement of food. Foregut opens in to midgut through stomodael / cardiac valve. Proventriculus 2. Midgut (Ventriculus or mesenteron or stomach),(Middle)  Endodermal in origin.Is concern with; i.Secretion of Enzymes,ii.Digestion of food, iii.Absorption of food.  An endodermic cell does not secrete intima but instead of that secretes delicate membrane called Peritrophic membrane.  Midgut consists of an inner delicate layer called peritrophic membrane secreted by the epithelial cells. The peritrophic membrane protects the tender epithelial cells of the midgut from abrasion by hard food particles. Present in solid feeders and absent in sap feeders.  The midgut is a long tube it carries eight small blunt tubes known as gastric or hepatic or enteric caeca. It increase the surface area of malpighian tubules and they are secretary and absorptive in function.  Filter chamber:  This is a characteristic arrangement of the midgut in hemipteran insects (fluid feeders).  This is closely bound to either posterior part of midgut or the anterior hindgut and Malpighian tubules.  Filter chamber enables the excess fluids including sugar in the food to pass directly from the anterior part of the midgut to the hindgut without passing through the middle portion of midgut thus preventing excessive dilution of haemolymph, enzymes and facilitate better enzyme activity. 50 Theory Notes on Fundamentals of Entomology  Prof. Mochi A. S. (K. K. Wagh College of Agriculture, Nashik) Filter chamber  Pyloric valve or proctodeal valve: Present between midgut and hingut, which regulate food flow. 3. Hindgut (Proctodaeum) (Posterior)  Ectodermal in origin.Intima present.  In termites, digestion takes place in colon of hindgutwhich secretes the enzyme cellulase for digest the wood material rich in cellulose.  Anterior end of the hindgut can be marked by the presence of a set of malpighian tubules which are excretory in function.  Hindgut is divided into 3 regions namely ileum, colon and rectum. i. Ileum is a small intestine (or) tube like structure. ii. Colon is a large intestine. iii. Rectum - The rectum may sometimes get differentiated into rectal papillae (or) pads which vary in number from 3-6. These are involved in reabsorption of water, salts from the faecal (waste) matter.  Salivary glands:-  These are a pair of glands involved in the secretion of salivary juices.  These glands present either sides of esophagus which open at the base of the hypopharynx through small salivary ducts.  In case of silkworm (or) lepidopteran larvae, the salivary glands produce silk and anti-coagulants