insect anatomy and insect body wall and their physiology

the ppt provide all the notes about insect anatomy

1. Course No. – ENTO-121 TITLE-FUNDAMENTALS OF ENTOMOLOGY Dr. Anita Sharma Asstt . Professor (Entomology)

2. Entomology- Greek word ( Entomon = Insect; Logos = Study) It is the branch of zoology or biological science that deals with the study of insects . INTRODUCTION Insect : - The insects are the tracheate arthropods in which the body is divided in to head, thorax and abdomen possessing 2 pairs of wings. 3 pairs of working legs. 1 pair of antennae. Segmented body. Having complete and incomplete metamorphosis.

3. Insect is Greek word = Cut in pieces or segmented. Insects belong to the Phylum Arthropod a ( Artho = jointed, Poda = Legs) which is the biggest phylum of kingdom Animalia . More than three quarters of the animals on earth are arthropods, and most of these are insects. Kingdom Animalia is classified into twelve phyla. INTRODUCTION

4. Study and use of insects in crime investigations is known as Forensic Entomology . Study of insects related to live stock and veterinary animals is known as Veterinary Entomology . Study of insects in relation to Human beings is known as Medical Entomology . Study of insects in relation to Agriculture is known as Agriculture Entomology Branches of Entomology

5. Topic -1, HISTORY OF ENTOMOLOGY IN INDIA Aristotle (384-322 B.C.)– Father of biological classification . First person grouped insects in winged and wing less groups. He gave the terms like Coleoptera and Diptera . Carolus Linnaeus (1758)– Father of Taxonomy . William Kirby considered as “Founder of Entomology ” because of his significant role in Entomology in the world. He published a book “ An Introduction to Entomology” (1815-1826). Snodgrass R. E. (1875)– referred as a Father of Insect Morphology . He wrote book - Principles of Insect Morphology. Mithan Lal Runwal (1908)– Outstanding work on termites/ white ants. Contributions to ecology, embryology and locust. 1940 - Dr. T.V. Ramakrishna Ayyar published the book " Handbook of Economic Entomology " which met the long felt need of the students of Agriculture and agricultural scientists as well and also known as “Father of Indian Entomology”. Dr.S.Pradhan (1969) - Wrote a "Insect Pests of Crops" and Father of Modern Applied Entomology in India.

6. History of Entomology in India 1758 - 10th edition of Systema Naturae by Linnaeus with only 12 Indian insects which was the earliest record. 1779 - Dr. J.G. Koenig - Medical Officer initiated the work on Indian insects on scientific lines. He also published a special account of the termites of Thanjavu r District. 1782 - Dr. Kerr Published on account of lac insect. 1785 - Asiatic Society of Bengal started in Calcutta and many papers were published in the Societys publications. 1790 - Roxburgh (Botanist) published a detailed account of lac insect. 1791 - Dr. J. Anderson issued a monograph on Cochineal scale insects 1800 - Buchanan ( Traveller ) wrote on the cultivation of lac in India and on sericulture in some parts of South India. Denovan published Natural History of Insects which was the first contribution on the insects of Asia and was revised in 1842 by West Wood. 1875 - Foundation of the Indian Museum at Calcutta

7. 1883 - Bombay Natural History Society was started. After the foundation of these two organisations scientific studies received greater attention in India. Numerous contributions of Indian insects were published in the Journal of the Bombay Natural History. 1893 - Rothney published on Indian Ants (earliest record of biological pest control in India) i.e. White ants attach on stationary items was kept free by red ants. 1897 - Bingham's issued volumes on "Hymenoptera ' (Ants, bees and wasps). Since than volumes on other groups of insects like Coleoptera (beetles), Hemiptera (bugs), Odonata ( dragenfly and damselfly), etc., were published. 1889 - Indian Museum, Calcutta published the Indian Museum Notes in five volumes. 1901 - (Lionel de Nicevelle ) posting of the first entomologist to the Government of India. 1905 - Establishment of Imperial Agricultural Research Institute at Pusa (Bihar). Maxwell Lefroy became first Imperial Entomologist of Govt. of India. 1906 - “Indian Insect Pests” & “Indian Insect Life” Books by Professor Maxwell . Subsequently State Governments also took up entomological work. 1914 - T.B. Fletcher, the first Government Entomologist of Madras State , published his book "Some South Indian Insects".

8. 1916 –”Indian Forest of Economic Importance: Coleoptera ; was published by the first Imperial Forest Entomologist E.P. Stebbing ”. 1921 - Indian Central Cotton Committee to investigate on pests of cotton. 1925 - Indian Lac Research Institute. 1934- Hem Singh Pruthi as Imperial Entomologist, start ‘Entomological Society of India ’ in 1938. Afzal Hussain was the first president of the society and VC were HS Pruthi and Ayyar . 1940 - Dr. T.V. Ramakrishna Ayyar published the book " Handbook of Economic Entomology " which met the long felt need of the students of Agriculture and agricultural scientists as well and also known as “Father of Indian Entomology”. 1968 - Dr. M.S. Mani's "General Entomology" 1969 - Dr. H.s. Pruthi's "Textbook of Agricultural Entomology". Dr. Pradhan's "Insect Pests of Crops“ 1946 - Government of India started the "Directorate of plant protection, quarentine and storage.". 1960 - "The Desert Locust in India" monograph by Y.R. Rao . 1969 - "The monograph on Indian Thysanoptera " by Dr. T.N. Ananthakrishnan

9. 1912– Plant Quarantine Act. 1914– Destructive Insects and Pests Act ( DIPA ). 1916– Imperial Forest Research Institute at Dehradun . 1925– Indian Lac Research Institute started at Ranchi. 1937– A laboratory for storage pests was started at Hapur , U.P. 1937- Establishment of Entomology division at IARI New Delhi. 1939– Locust Warning Organization established at Jodhpur. 1946– ‘Directorate of Plant Protection, Quarantine & Storage at Faridabaad . 1968– ‘Central Insecticide Act’. Institutes/Organizations

10. NCIPM , New Delhi- (National Centre for Integrated Pest Management - 1988). PDBC , Bangalore- (Project Directorate of Biological Control -1993). NBAIR -National Bureau of Agricultural Insect Resources and formerly it is a NBAII, Bengalore in 1957. CIB , Faridabad – Central Insecticide Board. NPPTI , Hyderabad– National Plant Protection Training Institute. Entomological Institutes

11. FACTORS FOR INSECTS ABUNDANCE Measures of dominance 1. More number of species : In the animal kingdom more than 85 per cent of the species belongs to insect group. Total number of insects described so far is more than 9 lakhs . 2. Large number of individuals in a single species: e.g., Locust swarm comprising of 10 9 number of individuals, occupying large area. 3. Great variety of habitats: Insects thrive well under varied conditions. 4. Long geological history : Insects were known to occupy this earth for more than 350 million years, which is a good track record. This has given the insects great variety of adoptions under different conditions.

12. Reasons for dominance Capacity for flight: Insects posess wings, which is the lateral extension of exoskeleton. Insects are the earliest animals and the only flying invertebrates. Flight is used for the following purpose- To seek food, mate, shelter and oviposition sites To colonize in a new habitat and also to exchange habitat. To escape from enemies and unfavourable conditions. To migrate (i.e. for long distance travel e.g. Locusts) Adaptability or Universality: Insects are the earliest groups to make their life on the earth and to occupy vast habitats of soil and water. i . Found in wide range of climatic conditions, from -50 ñ C to 40 ñ C. ii. Psilopa petroli found in crude petroleum well. iii. Ephydra fly living in great salt lake. iv. Every flowering plant providing food for one or many Phytophagous insects. v. Even the decomposing materials serving as food for many Saprophagous insects. vi. Many Carnivorous insects are parasitic on other animals and insects.

13. 3. Size : Majority of insects are small conferring the following physiological and ecological advantages. i . Less space, food, time and energy requirements for development and sustaining life. ii. Energy Utilization maximum. iii. Less gravitational effect. iv. Muscular action and tracheal respiration more effective. v. Easy escape from enemies. 4. 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. Uses: i.Act as external armour ii.Provides space for muscle attachment iii.Prevents water loss

14. 5. Resistance to desiccation : Insects minimise the water loss from their body surface through the following processes. I. Prevention of water loss: i . Lipids and polyphenols present in the Epicuticle acts as water proofing. ii. Was layer with closely packed wax molecules prevents escape of water. iii. Spiracles are closed to prevent water loss. iv. In the egg stage shell development prevents water loss and desication of inner embryos. II. Conservation of water i . Capable of utilizing metabolic water ii. Rectal resorption of water from faeces . iii. Terrestrial insects use less quantity of water to remove the nitrogenous waste (Uric acid) which is water insoluble. 6. 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.

15. 7. Reproductive potential: Reproductive potential of insect is high due to the following reasons: i Egg laying capacity (fecundity) is high. e.g., Queen termite lays 6000 - 7000 eggs per day for 15 long years. ii. Development period is short. e.g., Corn aphid produces 16 nymphs per female which reaches the adulthood within 16 days. There by one generation is completed within a short period of 16 days, which favours greater genetic changes in the insect population, like quicker development of insecticide resistant strains. iii. Careful selection of egg lying sites and protection of eggs. iv. Exhibits parental care like progressive provisioning (e.g. bees) and mass provisioning (e.g. Wasps) v. Presence of special types of reproduction other than oviparity and viviparity . * Polyembryony : Development of many individuals from a single egg. e.g. parasitic wasps. * Parthenogenesis : Reproduction without male or without fertilization, e.g. aphids * Paedogenesis : Reproduction by immature stages. e.g. certain flies.

16. 8. Complete metamorphosis: More than 82 per cent of insects undergo complete metamorphosis ( Holometabolous insects) with the following four stages. i . Egg: Inactive, inexpensive, inconspicuous and embryo develops inside. ii. Larva: Active, feeds, digests, grows and store food. iii. Pupa: Inactive, internal reorganisation and resist adverse conditions. iv. Adult: Active, reproduce and disperse. As the larval and adult food sources are different, competition for food is less. 9. Defense mechanisms: By using the following defense mechanisms, insects escape from the enemies to increase their survival rate. i . Behavioural : Thanatosis - insects pretends as if dead. e.g. some beetles. ii. Structural e.g. hardened forewings of beetles known as elytra protect the beetles from predation of birds. iii. Colourational : Presence of protective colours . e.g.Stick insects iv. Chemical : Presence of defensive chemicals. e.g. Bees producing venom 10. Hexapod locomotion: Insects uses 3 legs at a time during locomotion, while the remaining 3 legs are static, which gives greater stability.

17. POSITION OF INSECTS IN ANIMAL KINGDOM

18. POSITION OF INSECTS IN ANIMAL KINGDOM AND ITS RELATIONSHIP WITH OTHER ARTHROPODA Classification: 7 classes. Phylum : Arthropoda Classes : 1. Onychophora (claw bearing)e.g. Peripatus , has similarities with arthropoda like antenae , open circulatory system, walking legs with claw and tracheal system. 2. Crustacea ( Crusta - shell)e.g. Prawn, crab, wood louse 3. Arachnida ( Arachne - spider)e.g. Scorpion, spider, tick, mite 4. Chilopoda ( Chilo - lip; poda - appendage)e.g. Centipedes (carnivorous) 5. Diplopoda ( Diplo - two; poda - - appendage)e.g. Millipede ( scavengers) 6. Trilobita (an extinct group)- The dominant arthropodes in the early Paleozoic seas (many million ago) 7. Hexapoda or Insectae.g . Insects.

19. Characters of the Phylum Arthropoda : ( Arthro -joint, poda -foot) i . Segmented body ii. Segments grouped into 2 or 3 regions known as Tagmosis iii. Renewable chitinous exoskeleton iv. Grow by moulting v. Bilateral symmetry vi. Body cavity filled with blood- Haemocoel vii. Tubular alimentary canal with mouth and anus viii. Dorsal heart with ostia ix. Dorsal brain with ventral nerve cord x. Striated muscles xi. No cilia xii. Paired segmented appendages

20. Insect body wall – Integument/Exoskeleton External covering – ectodermal in origin Rigid, flexible, lighter, stronger and variously modified Insect Integument: Structure and Function

21. Consists of 3 layers : Structure Integument Cuticle Epidermis Basement membrane

22. Outer non-cellular layer – has 2 sub-layers Epicuticle : outer most layer – very thin – devoid of chitin Differentiated into 5 layers: Cement layer – outer most layer – made of lipid and tanned protein – protects wax layer. Wax layer – contains closely packed wax molecules – prevents desiccation Cuticulin – Non-chitinous polymerised lipoprotein layer – barrier to ions Outer Epicuticle Inner Epicuticle (It contain wax filaments) Cuticle. ...

23. Procuticle – divided into 2 – Outer exocuticle & Inner Endocuticle . Exocuticle : Outer layer – much thicker – composed of Chitin & Sclerotin – Dark and rigid Endocuticle – Inner layer – thickest layer – made of chitin & Arthropodin – Colourless, soft and flexible. Epidermis: Inner unicellular layer resting on basement membrane – Functions: Cuticle secretion Digestion and absorption of old cuticle Wound repairing Gives surface look

24. Composition .... Chitin: Main constituent of cuticle Nitrogenous polysaccharide and polymer of N- acetylglucosamine . (water insoluble and soluble in acids, alkalies and organic solvents) Arthropodin : Untanned cuticular protein (water soluble). Sclerotin : Tanned cuticular protein (water insoluble). Resilin : Elastic cuticular protein – for flexibility of sclerites .

25. Cuticular in growth of body wall – provide space for muscle attachment. 2 types: Apodeme – hollow invagination of body wall (ridge like) Apophysis – Solid invagination of body wall (spine or fingure like) Endoskeleton. ..

26. 31

27. Clothing hairs, plumose hairs. e.g. Honey bee. Bristles. e.g. flies 32

28. Scales - flattened out growth of body wall e.g. Moths and butterflies 33

29. Glandular seta. et. caterpillar 34

30. Sensory setae - associated with sensory neuron or neurons 35

31. Seta - hair like out growth (Epidermal cell generating seta is known as Trichogen , while 36

32. 37 Multicellular e.g. Spur - movable structure Spine - Immovable structure

33. GLANDS Cuticular glands are either unicellular or multicellular. Following are some of the examples . i . Wax gland - e.g. Honey bee and mealy bug ii. Lac gland - e.g. Lac insects iii . Moulting gland secreting moulting fluid. iv . Androconia or scent scale - e.g.moth v . Poison gland - e.g. slug caterpillar 38

34. Wax gland - e.g. Honey bee and mealy bug 39

35. . Lac gland - e.g. Lac insects 40

36. Moulting gland secreting moulting fluid 41

37. Poison gland - e.g. slug caterpillar 42

38. Functions of Body wall i . Acts as external armour and strengthen external organs like jaws and ovipositor ii . Protects the organs against physical aberation , injurious chemicals, parasites, predators and pathogen. iii . Internally protects the vital organs, foregut, hindgut and trachea. iv . Provides space for muscle attachment and gives shape to the body. v . Prevents water loss from the body. vi . Cuticular sensory organs helps in sensing the environment. vii . Cuticular pigments give colour. 43

39. MOULTING ( Ecdysis ) Ecdysis Periodical process of shedding the old cuticle accompanied by the formation of new cuticle is known as moulting or ecdysis . The cuticular parts discarded during moulting is known as Exuvia . Moulting occurs many times in an insect during the immatured stages before attaining the adult-hood. The time interval between the two subsequent moulting is called as Stadium and the form assumed by the insect in any stadium is called as Instar . 44

40. Steps in moulting 1. Behaviroual changes: Larva stops feeding and become inactive . 2. Changes in epidermis: In the epidermis cell size, its activity, protein content and enzyme level increases. Cells divide miotically and increases the tension, which results in loosening of cells of cuticle . 45

41. 3. Apolysis : Detachment of cuticle from epidermis 4. Formation of Sub cuticular space 5. Secretion of moulting gel in the sub cuticular space which is rich with chitinase and protease. 6. New epicuticle formation: Lipoprotein layer ( cuticulin ) is laid over the epidermis. 46

42. 7. Procuticle formation: Procuticle is formed below the epicuticle. 8. Activation of moulting gel: Moulting gel is converted into moulting fluid rich in enzymes. This activates endocuticle digestion and absorption. 9. Wax layer formation: Wax threads of pore canals secrete wax layer. 10. Cement layer formation : Dermal glands secretes cement layer ( Tectocuticle ). 47

43. 11. Moulting : This involves two steps   i . Rupturing of old cuticle: Insect increases its body volume through intake of air or water which enhances the blood flow to head and thorax. There by the old cuticle ruptures along predetermined line of weakness known as ecdysial line ii. Removal of old cuticle: Peristaltic movement of body and lubricant action of moulting fluid helps in the removal of old cuticle. During each moulting the cuticular coverings discarded are the cuticular of legs, internal linings of foregut and hindgut and trachea . 12.Formation of exocuticle : The upper layer of procuticle develops as exocuticle through addition of protein and tanning by phenolic substance . 13.Formation of endocuticle : The lower layer of procuticle develops as endocuticle through addition of chitin and protein. This layer increases in thickness. 48

44. Control of Moulting: It is controlled by endocrine gland like prothoracic gland which secrete moulting hormone. Endocrine glands are activated by prothoracico -tropic hormones produced by neurosecretory cells of brain. 49

45. Moulting: Shedding of old cuticle accompanied by formation of new cuticle is called Moulting or Ecdysis . Detachment of cuticle from the epidermis is apolysis The time interval between two moults is called a stadium The formation of an insect during a stadium is called an instar The cast off skin by an insect is called as exuviae Chitin which makes up the exo -and endocuticle is a nitrogenous polysaccharide formed from long chains N-acetyl D-glucosamine units ( C 8 H 13 O 5 N) n 50

46. BODY SEGMENTATION OF INSECT & INSECT HEAD

47. Cockroach and Grasshopper 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 ”. 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.

48. 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 segments i.e., mouthparts, 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.

49. Fig. General Organization of Insect Body

50. INSECT HEAD

51. It is the foremost part in insect body consisting of 6 segments that are fused to form a head capsule. Labral , antennary, ocular, mandibular , maxillary and labial segments. 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 tentorium which 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.

52. 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 and 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.

53. ( b) Prognathous : (Pro– infront and 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

54. (c) Opisthognathous : ( Opistho – behind and Gnathous Jaw) It is same as prognathous but mouthparts are directed backward and held in between the fore legs. This is also kwown as Hemipteroid or Opisthorhynchous type. Eg : bugs, Mosquito

55. 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 ).

56. Generally insect possess the following sclerites : Vertex: It is the top portion of epicranium which lies behind the frons or the area between the two compound eyes. 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. Facial area below the vertex and above clypeus 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.

57. 5. Occiput : Cranial area between occipital and post occipital suture . 6. Post occiput : It is the extreme posterior part of the insect head that remains before the neck region. 7. Occular sclerites : These are cuticular ring like structures present around each compound eye. 8. Antennal sclerites : These form the basis for the antennae and present around the scape .

58. Fig. Anterior view or face view

59. The common sutures present in head are: Clypeolabral suture: It is the suture present between clypeus and labrum . 2. Clypeofrontal suture or epistomal suture: The suture present between clypeus and frons . 3. Epicranial suture: It is an inverted ‘Y’ shaped suture distributed above the facial region extending up to the epicranial part of the head. 4. Occipital suture: It is ‘U’ shaped or horseshoe shaped suture between epicranium and occiput .

60. 5. Genal suture: It is the sutures present on the lateral side of the head i.e. gena . 6. 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. 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.

61. Insect Thorax And abdomen

62. Thorax Middle tagma Three segmented - pro, meso and meta Meso and meta thorax with wing are called as Pterothorax Thorax is made of three scleritic plates 1. dorsal body plate - Tergum or Nota 2. ventral body plate ( Sterna ) 3. lateral plate ( Pleura )

63. Thoracic nota 3 segments - pronotum , mesonotum & metanotum respectively Pronotum - undivided & Saddle shaped in grass hopper, Shield like in cockroach Pterothoracic notum - h ave 3 transverse sutures ( Antecostal , Pre scutal and Scuto-scutellar ) & 5 tergites ( Acrotergite , Prescutum , Scutum , Scutellum and Post- scutellum )

64. Thoracic sterna Vental body plate - prosternum , mesosternum and metasternum Made up of a segmental plate called Eusternum and a intersternite called Spinasternum Eusternum - made of three sclerites - presternum , basisternum and sternellum

65. Thoracic pleura Lateral body wall between notum & sternum Selerites of pleuron is called as pleurites fuse to form Pleural plate Pleural plate is divided into anterior episternum and posterior epimeron by Pleural suture Pterothoracic pleuron provides space for articulation of wing and Two pairs of spiracles are also present in the mesopleuron and metapleuron .

66. ABDOMEN Third and posterior tagma This tagma is made up of 9-11 Uromeres (segments) and is highly flexible abdominal segments are interconnected by a membrane called conjunctiva Each abdominal segment is made up of only two sclerite 1. Tergum 2. Sternum

67. ABDOMEN Eight pairs of spiracles in - first eight abdominal segments in addition to a pair of tympanum in the first abdominal segment Eight and ninth segments - female genital structure Ninth segment - male genital structure . Cerci

68. INSECT ANTENNAE: STRUCTURE, FUNCTIONS AND MODIFICATIONS

69. 75 What is Antenna (Plural= Antennae) ? “Antennae are paired , freely mobile , segmented sensory appendages articulated with the head in front of or between the eyes . Antennae are also known as feelers .” These are well developed in adults and poorly developed in immature stages . Antennae are absent in order Protura and Class Arachnida while 2 pairs of antennae present in Class Crustacea .

70. 76 Structure of Antenna “Antennae are multi segmented and may be divided into 3 parts:- Scape :- It is the basal segment of a antenna, by which it is attached with the head . Pedicel :- It is the second segment of antenna which is shorter than scape . This segment having a sensory apparatus named ‘Johnston organ’. Flagellum :- It is the last segment of antenna which consists the remaining divisions of antenna and it greatly varies in its form and structure . It is also known as Clavola .

71. 77 Structure of Antenna

72. 78 Functions of Antennae The main function of antenna is sensory , which is modified according to habit and habitat of insect as given below:- Organs of smell :- Some insects have smell organs on their antennae by which they recognise their food . E.g. Ant, Honey Bee and Jiant moths .

73. 79 Organs of taste :- Some insects have taste hairs on their antennae by which they recognise the taste of their food . E.g. Cockroach .

74. 80 4. Chordotonal Organs :- Hearing organs ( Jhonston’s organ ) found in second segment ( pedicel ) of antenna. e.g. Male mosquito, Green bottle fly and Paper wasp etc. 5. Sexual Dimorphism :- Some insect belonging to the order Diptera and Hemiptera , having different type of Antenna in male and female, which help in sexual dimorphism . e.g. Male and Female Mosquito .

75. 81 Other Functions :- (a). Help the mandibles for holding the prey . (b). Useful for clasping the female during copulation . (c). Butterfly bears some transmitting and receiving organs in their antennae.

76. 82 Modifications of Antennae On the basis of shape and structure, the antennae may be following type:- Setaceous :- These are bristle like antennae, in which segments gradually decrease in size from base to apex and tappering into a point , presenting a whip like structure. e.g. Cockroach and Cricket .

77. 83 2. Filiform (Thread like ):- It is thread like antenna in which segments are uniform in thickness throughout from base to apex and never ends with bristle . e.g. Insect of order Orthroptera , Coleoptera namely Grasshopper and Ground Beetle .

78. 84 3. Moniliform (Like string of beads ):- Such type of antennae have globular or oval shaped segments with uniform thickness from base to apex , by which it looks like string of beads . It have constriction between the joints . e.g. Insect of order Isoptera namely Termite.

79. 85 4. Pectinate (Comb like ):- This is a comb like in structure in which each segment of the antenna possess long projection on one side , giving comb like appearance . e.g. Insect of order Lepidoptera namely Moth of Sugarcane root borer.

80. 86 5. Bipectinate (Double Comb like ):- In this type of antenna, each segment has the long projections on both side , giving double comb like appearance. e.g. Insect of order Lepidoptera namely Silk Moth.

81. 87 6. Serrate (Saw like ):- In this type of antenna, each segment is more or less triangular and projected on one side , which giving teeth of saw like appearance. e.g. Insect of order Coleoptera namely Pulse beetle.

82. 88 7. Flabellate (Feather like ):- In this type of antenna, in which projections of the flagellum become long and form a feather like structure , which is known as flabella . e.g. Insect of order Coleoptera namely Cedar Beetle.

83. 89 8. Plumose ( bursh like with dense hairs ):- In this type of antenna, each segment has the whorls of hairs arise from their joints and look like plumose. e.g. Insect of order Diptera namely Male Mosquito.

84. 90 9. Pilose ( bursh like with sparse hairs ):- In this type of antenna, each segment has the whorls of hairs arise from their joints like plumose but whorl contains less number of hairs . e.g. Insect of order Diptera namely Female Mosquito.

85. 91 10. Whorled :- Basically these are the setaceous , filiform or moniliform type of antennae in which each segment has a whorl of bristle at every joint . e.g. Insect of order Hemiptera namely Male of Mango Mealy Bug.

86. 92 11. Clavate (Clubbed ):- In this type of antenna, segments gradually increase in diameter towards the tip and last segment finally ending into a round core, look like club . e.g. Insect of order Lepidoptera namely Butterfly.

87. 93 12. Capitate (Clubbed with Knob ):- In this type of antenna, segments gradually increase in diameter towards the tip and suddenly last 3-5 segments enlarge to form a knob like structure. e.g. Red Rust Flour Beetle .

88. 94 13. Lamellate (Plate like ):- This is a modification of capitate antennae in which terminal segments extended on the side to form leaf like plate instead of forming the knob . e.g. Rhinoceros Beetle, Dung Rollers etc .

89. 95 14. Geniculate (Elbowed ):- In this type of antenna, the scape is greatly elongated , pedicel is short and flagellum is made up of small segments which make a bent on the scape look like knee . e.g. Ants, Honey Bee etc.

90. 96 15. Aristate (With arista ):- In this type of antenna, scape is smaller and broader , pedicel is longer than scape . The flagellum is longer than both and bears heavy bristle known as arista . e.g. House Fly .

91. 97 16. Stylate (With style ):- In this type of antenna, last segment of flagellum is modified into a long bristle known as style. e.g. Snipe fly, Robber fly.

92. 98 17. Fusiform :- In this type of antenna, scape is smaller and thin , while pedicle is larger and flagellum is modified into a hook like structure. e.g. Sphingid Moth.

93. DIFFERENT TYPES OF MOUTHPARTS Biting and Chewing type Chewing and lapping type Lacerating and sucking type Piercing and sucking type Sponging type Siphoning type Mask type Degenerate type

94. BITING AND CHEWING MOUTH PARTS ORDER: ORTHOPTERA, eg : grasshopper Mouth parts are typical mandibulate type useful for biting, chewing and consisting of Labrum (upper lip) Mandibles ( Ist pair of jaws) Maxillae (first maxilla-2nd pair of jaws) Labium (second maxilla or lower lip-3 rd pair of jaws) Hypopharynx (tongue).

95. Labrum : A simple plate like structure situated below the clypeus on the anterior side of the head and moves up and down. The functions of the labrum are to close the front of the moth cavity, protect the mandibles, guide the food into the mouth.

96. Mandibles: Paired un segmented, heavily sclerotized jaws lying immediately below the labrum. Articulate with the headcapsule side wise by means of two joints; ginglymus and condyl . Possess two types of teeth; incisors and molars. Adopted for cutting and masticating the food material.

97. Maxillae: Paired segmented structures lying below the mandibles. Each maxilla bears a feeler-like organ, the palpus (which discharges a gustatory or tasting function). Have two segments, the basal cardo and apical stipes . Palpus arise on a lobe of the stipes called the palpifer . Stipes bears two lobe like structures at its apex (outer simple galea and inner jaw like structure lacinia ) Functionally maxillae are of accessory jaws, their lacinia aiding mandibles in holding the food.

98. Hypopharynx : A short tongue like structure located above the labium and between the maxillae. The ducts from salivary glands open on or near the base of hypopharynx . Labium: Lies behind the maxillae Derived by the fusion of the second pair of maxillae, hence also referred as the second maxillae.

99. Divided by transverse suture (labial suture) into two portions, basal postmentum and distal prementum Postmentum is usually divided into basal submentum and distal mentum . Prementum bears a pair of palpi called labial palpi and a group of apical lobes which constitute the ligula . Labial palpi arise on lateral lobes of the prementum called palpigers . Ligula consists of a pair of small lobes in the middle, inner glossae and outer paraglossae . Labial palpi act as sense organs comparable to the gustatory function of maxillary palpi .

100. Biting and chewing mouth parts

101. Biting and chewing mouthparts

102. Feeding mechanism : The labrum or upper lip helps the insect to pull the food into the mouth. Mandibles masticate the food. They cut off the food material. Small teeth present in each mandible work against those of the opposite for effective grinding. The maxillae aid in holding the food in mouth while it chewed by mandibles. They also aid in breaking up the food. Both maxillae and mandibles move side ways. Labial palpi works similar to that of maxillary palpi . The maxillae and labium helps in passing the food into oesophagus

103. Grasping Type Mandibles – slender, elongate, curved at their ends bearing 1-3 sharp teeth. Extreme development in males of many of the Lucanidae and Chiasognathus Maxillae – Single-lobed in lucanids called “mala” Other parts – normal Soldiers of Termites – Large, twisted, asymmetrical mandibles with peculiar “snapping action”. Some posses salivary or frontal glands (adhesive secretions). Examples : Soldier termites and stag beetles ( Lucanids )

104. Grasping Type Soldier termite

105. GRASPING AND SUCKING TYPE Mandibles and maxillae – long, exerted adopted for seizing the prey Mandibles – sickle – shaped and armed with teeth. Grooved along their ventral surface and a lobe or maxillae (perhaps lacinia ) similar in size and shape fits each groove forming a pair of imperfect suctorial tubes. Blood imbibed by means of pumping action of pharynx. Maxillary palpi – absent; labium – greatly reduced, labial palps - variable or aborted Examples : larvae of Antlions and Aphid lions, Lampyrid larvae.

106. GRASPING AND SUCKING TYPE Antlion larva

107. . SCRAPING TYPE Mouthparts – adopted for dealing with liquid and soft food. Labrum – membranous and concealed Mandibles – membranous, thin, sometimes concealed, incapable of biting, used for moulding wax mud, dung etc. Maxillae – inverted with long hairs, used for feeding pollen (in pollen feeders) Ligula sometimes atrophied, galeae – free Examples : Pollen feeders (e.g. Yucca moth, Tegeticula yuccasella feeding on Yucca filamentosa ) dung beetles ( Scarabaeinae )

108. Dung beetle

109. BITING AND MASTICATION AND LICKING TYPE Mandibles – eventually biting nature Maxillae – Comparatively little modified, palps are 6- segmented Laciniae – reduced to small scales Galeae – broad membranous lobes Labium – large shield – shaped prementum; bearing 4-segmented labial palps Ligula – curiously elongated paraglossae and a wide bilobed glossa . Examples : Vespula germanica (worker) and the Primitive bee ( Hylaeus )

110. BITING AND MASTICATION AND LICKING TYPE Vespula germanica

111. SIPHONING OR SIMPLE SUCKING TYPE Order: Lepidoptera, e.g.: butterflies and moths Mandibles totally absent. Majority of Lepidoptera mandibles are wanting and maxillae to form a suctorial proboscis Maxillae is composed of elongated galea . Each galea of maxillia elongated, semi-circular towards inner side. Galea of both the sides meet together forming into a tubular structure, proboscis. Observe the coiled proboscis beneath the head. Liquid food is imbibed through groove formed by galea

112. All other mouth parts highly reduced. When fully developed mouth parts, maxillary palpi are 5 or 6 segmented. Labium reduced to small ventral plate. Hypopharynx is present on floor of mouth. Feeding mechanism: When not in use, proboscis is spirally coiled and beneath the thorax. It presents an extraordinary variation in length. Eg . Sphingidae , Danaus . According to Breitenback they are often developed into denticulate spines. Proboscis extended by blood pressure. Eastham and Eassa (1955).

113. SIPHONING OR SIMPLE SUCKING TYPE

114. PIERCING AND SUCKING TYPE Order : Hemiptera Mandibles and maxillae being modified to form slender bristle like stylet which rest in grooved labium. Both pairs of stylets are hollow seta-like structures. These stylets back into prothorax (Cranston and Sprague, 1961). Stylets withdrawn into a pocket connected with the channel of the labium. Mandibular stylets form anterior (outer) pair and posterior pair of stylets (inner) constitute part of maxilla. Dorsal stylet as a suction canal.

115. Ventral stylet as a salivary canal. Labium no part in perforating the tissue of host plant. Hypopharynx is highly specialized in Hemiptera . Salivarium is modified into a powerful salivary pump. Feeding mechanism: At rest rostrum is flexed beneath the body. In most Hemiptera stylets are only slightly longer than the rostrum. Eg . Aphididae , Lygus . In Coccoidea stylets are forced deeper and deeper into the plant. Mandibles are first pushed then followed by maxillae.

116. PIERCING AND SUCKING TYPE

117. SPONGING TYPE Eg : HOUSEFLY. Mandibles are absent. Maxillae are represented by a pair of maxillary palp . Labium is divided into basal rostrum, middle haustellum and distal labellar lobes. Labella are tranversed by small channels known as pseudotrachia which converge at one point and open into the food channel. Epipharynx and hypopharynx together form the food channel which leads to Oesophagous

118. Mode of feeding: It is used for food which is either liquid or readily soluble in saliva. While feeding after dissolving the food by saliva, the labella is thrust into the liquid food as a result the pseudotracheae get filled with the liquid by capillary action. The food is then passed through the food channel to the Oesophagous Eg . Houseflies

119. CHEWING AND LAPPING TYPE Eg : HONEYBEES Mandibles and labrum are of chewing type and help in bolding the food. Maxillae and labrum are elongated and united. There are suspended from the cranium and articulate to it through the base of the maxillae. Maxillae : Palps are very small Galea with its concaves inner surface forms a roof over the glossa and fits length wise against labial palps . In this way a food channel is formed.

120. Labium: Palps are long and form food channel with galea Glossae are fused to form a channeled organ termed as alaglossa which can reach deep into nectar of blossoms. Mode of feeding: The mandibles and labrum help in holding food / prey. In honey bees the labrum is used for molding wax into cells. Regarding intake of nectar king, Imm’s and Snodgrass gave their own view.

121. King’s Views : After sucking the nectar with the tip of glossa , it is retracted into labial palp and galea , where the latter squeezes off the nectar which is deposited at the base of the glossa in a small cavity formed by the paraglossa . Finally as a result of bending of the labium upward, the base of the glossa comes near the mouth cavity and the accumulated nectar is sucked into the Oesophagous by the action of the pharyngeal pump.

122. CHEWING AND LAPPING TYPE

123. MASK TYPE These are modified biting and chewing type. Labrum, mandibles, maxillae, hypopharynx are typically developed as in biting type of mouth parts. Labium – in the nymph this organ is modified for prehensile purpose and is known as mask. The prementum and post mentum are markedly lengthened. The ligula is undivided and represented by a median lobe which is fused with the prementum. The labial palpi are modified to form a lateral lobes each of which carries on its outer side a movable hook. These hooks which help in catching the prey. Ex : Dragon fly naiads.

124. Naiad

125. DEGENERATE TYPE Eg : MAGGOTS In maggots, a definite head is always absent. The mouth parts are highly reduced and are represented y one or two mouth spines or hooks. Hypopharynx , clypeus and associated sclerites of the head form upper pharyngeal skeleton or hypopharyngeal sclerite around the beginning of the alimentary canal.

126. DEGENERAE TYPE

127. Lacerating and sucking or rasping and sucking type Order: Thysanoptera . eg . Thrips . Labrum , labium and bases of maxillae combine and unite to form a mouth cone. Both maxillae and the left mandible are modified as stylets . Right mandible rudimentary. Hypopharynx reduced.

128. Thrips

129. 140 Insect Legs and their modifications “An insect usually bears three pairs of legs which are located on the ventral surface of thoracic segments . They are primary organs for running or walking , but according to the habit and habitat of insects they are modified for different purposes.”

130. 141 Structure of Insect Leg A typical leg consists of the following parts:- Coxa :- It is the basal segment and joint the leg with thorax . Trochanter :- It is the small second division of the leg which articulates with coxa but is usually fixed with femur . Femur :- It is the largest and most powerful division of the leg. Tibia :- It is the slender , usually quite long . Tarsus :- It is the fifth divisional segment and generally sub divided into 2-5 segments . Pretarsus :- It is the last terminal segment of the leg which represented of the leg which is represented by a complex set of claws.

131. 142

132. 143 Modifications of Leg Ambutorial or Walking Type :- It is generalized form of insect leg, which is usually adapted for walking . Example:- Cockroach and Bugs

133. 144 2. Cursorial or Running Type :- It is almost similar to walking type of leg, but it is differentiated by the tarsus which is comparatively longer and touches the ground while running. Example:- Ants, Blister Beetle and wasps.

134. 145 Saltatorial or Jumping Type :- Such type of legs are present in grasshopper, crickets and flea beetle where the femur of the hind leg get enlarged and accomodates the powerful tibial muscles . Example:- Hind leg of Grasshopper

135. 146 4. Scansorial or Clinging Type :- This type of legs are smaller and flat . The coxa are widely separated and tarsi bears a single claw . Example:- Head Louse

136. 147 5. Fossorial or Digging Type :- This type of legs are modified for the purpose of digging . These are powerful, broad and small in size. Tibia and tarsus short and broad with teeth like projections . Example:- Mole crickets and Dung rollers.

137. 148 6. Raptorial or Grasping Type :- Such legs are adapted for catching the prey and are found in Mantids . Coxa of fore leg is more elongated whereas the trochanter is small . Tibia is spinous and fits along the femur . Example:- Preying Mantids

138. 149 7. Natatorial or Swimming Type :- These type legs are found in insects which lives in the water and help them to swim . The femur , tibia and tarsus are flattened and posses the long rows of hairs . Example:- Dytiscus and Jaint water bug.

139. 150 8. Foragial or Pollen Collecting Type :- This type of legs are found in worker honey bees which is mainly adapted for carrying the pollen from the flowers. Tibia of the hind leg is dialated and covered with longs dense hairs which forms a pollen basket . Example:- Hind leg of Woker Honey Bee.

140. 151 9. Stridulatorial or Sound Producing Type :- These legs are typically adapted for producing sound wherein the femur of hind leg is provided with the row of pegs on its inner side . These femoral pegs work against the outer surface of each tergum or coastal margin of the fore wing , thereby producing a sound . Example:- Male Grasshopper and cricket.

141. 152 10. Sticking Type :- In such type of legs the pretarsus is highly modified in a pair of claws and a pair of pad like structure known as pulvilli (found at the base of claws). Hollow and tubular hairs secrets a sticky substance . These are also known as Adhesive type of legs . Example:- House fly .

142. 153 11. Clasping Type :- This Such type of legs are modified for reproduction purposes . Coxa and Trochater is comparatively smaller while the Femur is thick . The tibia is slender , tarsus is one segmented and arched . This adaptation helps male to holds the female during reproduction . Example:- Chleredryinus (Parasite of Sugarcane Pyrilla )

143. 154 12. Suctorial or Sucking Type :- This type of legs are also modified for the purpose of reproduction in which coxa and trochanter of fore legs are small while femur is thick and small . They are also helpful in sticking with grasses and leaves against the water flow . Example:- Male Dytiscus .

144. 155 13. Antennal Cleaning Legs :- This type of legs are modified for the purpose of cleaning antennae in which tibia possess a movable spine and the first tarsal segment with a semi-circular notch. Example:- Front legs of Honey Bees.

145. 156 14. Wax Pick Legs :- This type of legs are modified for the purpose of picking of wax plate in which Tibia possess a spine called wax pick for removing the wax plates from the ventral side of the abdomen . Example:- Middle legs of Honey Bees.

146. 157 15. Prehensile :- This type of legs are modified for the purpose of catching prey and basket forming . Example:- Dragon Flies .