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Insect morphology

for 2nd year biology students

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Insect morphology

  1. 1. MANSOURA UNIVERSITY INSECT MORPHOLOGY For 2nd year biology By Dr. Zeinab Abu-Elnaga •Entomology 2014 Zoology Department, Faculty of Science Dr.ZAbu-Elnaga
  2. 2. COURSE OUTLINES o General introductory lecture. o External body morphology of insects and its modifications  Body apertures  The head capsule  Structure  Cephalic appendages 1. The antennae 2. The mouth parts  The thorax 1. The wings 2. The legs  The abdomen 1. The cerci 2. The genitalia 3. The styli 4. Stinging apparatus 5. Springing apparatus Dr.ZAbu-Elnaga
  4. 4. GENERAL LECTURE INSECTS  Systematic Position: Insects are members of one of the biggest classes of the….. Phylum: Arthropoda (Nonchordata with jointed legs) Class: Insecta (Hexapoda) (i.e. =six-legged or possess 3 pairs of legs) .  General Characters: A- Characters common between insects and other arthropods:  Triploblastic coelomate with bilateral symmetry  Segmented body and jointed appendages.  Exoskeleton.  Locomotory system with skeletal muscles.  3 pairs of peristomal appendages.  Sense organs, Antennae (tactile & olfactory) & compound eyes.  Mostly Dioeceous (sexes separate)  Heamolymph (corresponding to both blood &lymph of vertebrates).  Blood circulation is open type.  Undergo metamorphosis (post-emberonic development). Dr.ZAbu-Elnaga
  5. 5. B- distinguish characters for insects:  Three regions body (head [cephalization], thorax, & abdomen). Only one pair of antenna, no antennules. Sessile compound eyes, (stalked in Arthropods). Peristomal appendages (mouth parts).  Thorax (pro-, meso-, & metathorax), each one with pair of legs.  Wings (meso- & metathorax).  Adults have no abdominal legs.  The space between the viscera is filled by fat tissue.  Tracheal system is well developed, and gills, but no lung books.  Excretion via malpighian tubules. Dr.ZAbu-Elnaga
  6. 6. ATTRIBUTESOFSURVIVALANDDOMINANCEININSECTS  Structural  Size & shape  The Exoskeleton  Advanced locomotory organs  The mouth parts  Central nervous system  The reproductive capacity  The digestive system  The fat tissue  Behavioral  Oviposition hapits  Protection of quiescent stages  Periodicity of activity  Hibernation & diapause  Feeding habits  Mimicry & protective coloration  Biological  Diversity of diet  Modes of reproduction  Life cycle duration  Metamorphosis  parasitism Dr.ZAbu-Elnaga
  7. 7. ECONOMIC IMPOTENCE OF INSECTS  Blood sucking insects (mostly temporary ecto-parasites on man or permanent ecto- parasite).  Disease transmission  Myasis to man & animals  Spoils our food & drink.  damage of cloths & furniture  Caused by insects which infest crop plants & beneficial animals.  Plant pests: locusts, larvae of many moths, thrips, fruit flies, ……..ect.  Animal pests: warble flies attack sheep & cattle, causing decreased efficacy, milk, & flesh……. Direct Indirect A-Injurious insects Dr.ZAbu-Elnaga
  8. 8. ECONOMIC IMPOTENCE OF INSECTS  Source of useful materials as food, (bees, Aphids “honey dew”, fried locusts, eggs of big insects,…….. ect.)  clothing (salivary secretions of silk worms)  Industry useful (natural dyes & inks).  Pharmaceutical materials.  Cross pollination.  Improvement of soil properties (ground beetles).  Source of food for birds & fishes, used, in turn food for man.  Discovery of juvenile hormone.  Some of them used as biological control agents. Direct Indirect B- Benefits of insects Dr.ZAbu-Elnaga
  10. 10. THE HEAD REGION & ITS APPENDAGES o Insects have a distinct and well developed head region = Cephalization. o unsegmented, but it actually consists of a number of fused segments. brain Mouth parts antennae Compound eyes Dr.ZAbu-Elnaga
  11. 11. THE HEAD CAPSULE  Corresponds to the cranium of vertebrates.  The typical structure evident in locusts & cockroaches. Dr.ZAbu-Elnaga
  12. 12. POSITIONS OF THE HEAD  Pro-gnathous: head extended longitudinally with body axis (m.p are pointed forward, Weevils)  Hypo-gnathous: head perpendicular to longitudinal body axis (m.p pointed downwards, Locust)  Opitho-gnathous: head bent underneath thorax during rest (m.p pointed backwards, Aphids) Dr.ZAbu-Elnaga
  13. 13.  Difintion: pair of jointed segments on front region of insects, mostly located within socket, & its surface carries numerous fine hairs. Function: tactile & olfactory organs (touch & smell respectively),moreover, in mosquito it was for hearing (auditory).  Typical structure: three main regions: 1. Scape: basal part articulates with head capsule, contains one segment almost, cylindrical in shape & movable in all directions. 2. Pedicel: short piece, connected to scape via memberanous narrow ring, for bending. 3. Flagellum: long estpart, many sub-segments, flexible, articulating basically with pedicle. Dr.ZAbu-Elnaga
  14. 14. TYPESOFANTENNAE  Setaceous  Filiform  Moniliform  Serrate  Capitate  Lamellate  Aristate  Pectinnate  Bipectinnate  Plumose  Pilose  Clavate  Geniculate  Stylate  flate Dr.ZAbu-Elnaga
  15. 15. TYPESOFANTENNAE  Setaceous: the subsegments of flagellum, tapering terminally, with seta shape (cockroach).  Filiform: the flagellum subsegments alomost equal in size, rod shaped, with blunted end (locust)  Monliform: the subsegments like beads of necklace (white ant)  Capitate: the terminal sub-segments enlarge suddenly, cap shaped (flour beetles).  Clavate: with large diametered subterminal segments, like knob (butter flies)  Pectinnate: each sub-segment carry a thin process on one side, comp shaped (♀ moths)  Bipectinate: comp on both sides (♂ moths).  Lamellate: leaf like subsegments, overlapping each other as a fan (Scarab beetle).  Geniculate: angled short flagellum, elbow-shaped (honey bee).  Plumose: setaceous type flagellum, but carring tufts of long hairs on both sides, feather shaped (♂ mosquito)  Pilose: hairs shorter & less than plumose (♀ mosquito)  Aristate: short, rod shaped & unsegmented flagellum, carries a thread like process called arista covered with hairs (house flies)  Stylate: blade like subsegments with pointed apor (Tabanus fly) Dr.ZAbu-Elnaga
  16. 16. INSECTMORPHOLOGY Dr.ZAbu-Elnaga
  17. 17. THE MOUTH PARTS •Typically evident in cockroach. •Modification is a functional adaptation -By reduction of un-needed parts -Enlargement of the impotent parts or change in its shape -Development of accessory parts Dr.ZAbu-Elnaga
  18. 18. M. P. OF BUTTERFLY (SUCKING TYPE)  Modifications according to functional adaptation. • Reduction of –Labrum • Absence of –mandible & hypoharynx. • Labium represented only by palps (tactile) • Maxillae fused together & modified into a sucking proboscis (the functional organ).  Proboscis: retractile, tubular, & developed from the two galeae by its elongation and rolling into a semi-tube within inter-locked hooks. Dr.ZAbu-Elnaga
  20. 20. M. P. OF HONEY BEE WORKER(BITING LAPPING TYPE)  Reduction of hypopharynx & labrum.  Modifications - Mandibles: 2 flattened rectangular plates, no teeth, no molar (used in cutting soft wax). - Maxillae: cardines rod shaped, stipi fused to form lorum. The galeae enlarged sheath. Lacinia, a small lobe at the base of the galea. - Labium: tongue-like proboscis. Fused, extended & rolled glossae. Dr.ZAbu-Elnaga
  21. 21. M.P.OFHONEYBEEWORKER(BITINGLAPPINGTYPE) Honey bee feeding Dr.ZAbu-Elnaga
  22. 22. Dr.ZAbu-Elnaga
  24. 24. ♀ ANOPHELES MOSQUITO Dr.ZAbu-Elnaga
  25. 25. MOUTHPARTSOF♀MOSQUITO(PIERCING-SUCKINGTYPE)  Modifications:  Labrum-Epipharynx: elongated flap roofing the Proboscies & covering the underlying mouth parts.  Mandibles: pair of thin, hollow long bristle, with pointed sharp ends. Adapted for piercing blood vessels & sucking their contents.  Hypopharynx: a sword-shaped structure extending between the mandibles & underneath the labrum-epipharynx. It has sharp edges for tearing the skin.  Maxillae: a pair of styles with serrated ends for scratching the skin (modified galea)  Labium: elongated, thick walled (protective sheath for the rest parts) Dr.ZAbu-Elnaga
  26. 26. MOUTH PARTS OF ♂ MOSQUITO  Not blood sucker (no mandibles) Maxillae (greatly reduced) Hypopharynx: fused with labium Maxillary palps (4 segments “club-shaped”) Don not forget the sexual dimorphism in the antennae. ♂Anopheles Dr.ZAbu-Elnaga
  27. 27. ♂ CULEX Dr.ZAbu-Elnaga
  28. 28. M. P. OF HOUSE FLY (SPONGING TYPE)  The head capsule is protruded into a funnel-shaped Rostrum. The pharynx extends through the rostrum as a narrow pipe. Dr.ZAbu-Elnaga
  29. 29. M.P.OFHOUSEFLY(SPONGINGTYPE)  Modifications:  Labium: a thick double walled ( haustellum).  Labrum-Epipharynx: consists of labrum, fused with the extended roof of the pre-oral cavity,.  Hypopharynx: a tongue-like structure resting along the floor of the haustellum, for receiving the salivary duct.  Food-Meatus: a narrow channel enclosed between the hypopharynx & the labrum- epipharynx. Extended till the mouth opening  Labellae: 2 big sponge lobs carried on the tip of the haustellum, for passage of saliva to dissolve food before absorption.  The mandibles: absent  The maxillae: reduced. Dr.ZAbu-Elnaga
  30. 30. INSECTMORPHOLOGY Dr.ZAbu-Elnaga
  31. 31. THORACIC REGION & ITS APPENDAGES Thorax Wings dorsally Legs ventrally Dr.ZAbu-Elnaga
  32. 32. THORACIC REGION  Carrier to the locomotory organs.  Each of the three segments carries one pair of jointed leg.  Dorsally on each of meso- & metathorax it posses one pair of wings and spiracles.  Typically structured from 3 sclerotized plates:  Tergite:( dorsal in position)  Sternite: (ventral)  Pleurites: (lateral) With supporting function from all sides, provide articulation for wings & legs, protection of the spiracles. o Between each segments an articulating and bending inter- segmental membrane, for bending & stretching. Dr.ZAbu-Elnaga
  33. 33. FORMS OF THORACIC SEGMENTS  Only in primitive insects & immature stages the thoracic segments similar in shape & equal in size. Dr.ZAbu-Elnaga
  34. 34. THORACIC APPENDAGE  The descriptions of the typical structure. Dr.ZAbu-Elnaga
  35. 35. MODIFICATIONS  The modification in different insects to suit the mode of locomotion or non- locomotory functions (food collecting). Running Cockroach Jumping Locust Walking upside-down House fly Dr.ZAbu-Elnaga
  36. 36. Seizing Fore-leg Prey mantis Burrowing Fore-leg Gryllotalpa Swimming Hind-legs Water beetles Dr.ZAbu-Elnaga
  37. 37. Food collecting Hind-leg of Honey bee worker Clinging Lice Dr.ZAbu-Elnaga
  38. 38. INSECTMORPHOLOGY Dr.ZAbu-Elnaga
  39. 39. THE WINGS  Most adult insects posses 2 pairs of wings (on meso- & metathorax) In flies & mosquitoes, the hind pair is reduced Wings are not modified legs as in birds & bats, but are additional locomotory organs. The base of wing articulates with the tergum & pleuron of the segment carrying it. This facilitates rotation of the wing during flight in various directions in relation to the body axis. Dr.ZAbu-Elnaga
  40. 40. TYPICAL STRUCTURE OF THE WINGS  Triangular, 3 regions (Jugum, Vannus, & Remigium)  Wing Axil, posses small sclerotic (support & articulation)  In the hind wings of most insects the 3 regions are separated from each other by 2 folds  This enables the insect to fold the hind wings during repose & unfold them during flight. Dr.ZAbu-Elnaga
  41. 41. HISTOLOGICAL STRUCTURE  Histologically, a wing is analogous to a plant leaf, contains double layer of flattened cells covered with extremely thin cuticle  Enclosing in between the wing veins (for aeration)& space for few blood cells  The wing surface carries hairs, scales or spicules Dr.ZAbu-Elnaga
  42. 42. WING COUPLING  For fixing the for-wing with the hind-wing  This coupling enables the insect to resist the opposing action while flying at considerable heights. 1- In honey bee: the costal margin of the hind-wing posses row of curved hooklets, that anchored to a chitinous ridge of the anal margin of fore-wing, (during Nuptial flight) 2- In some moths: the costal margin carries a process that can fit within a loop extending from the anal margin. 3- In other moths: the anal margin of the fore wing has 2 clefts enclosing a lobe between them, coupling by simple overlapping between the lope & the costar margin of the hind-wing. Dr.ZAbu-Elnaga
  43. 43. WINGCOUPLING Dr.ZAbu-Elnaga
  44. 44. TYPES OF WINGS  Wings of different insects differ in size, shape, texture & other structural details.  Fore-wing usually differ from the hind-wings of the same insect.  Function of wings: 1- flight ( rotationary vibrations effected by thoracic muscles). 2- Abdominal protective shield (fore-wing Elytera of beetles). 3- Balancing organs (modified hind-wing halteres in flies & mosquitoes). 4- Sound-producing organs for calling mates (♂ crickets). 5- Important for insect classification (different types & mode of development. Dr.ZAbu-Elnaga
  45. 45. TYPESOFWINGS 1- Tegmina (Leathery) Cockroach 2- Elytra (elytron) Coleopterous 3-Hemi-elytra Hemiptera 4- Hairy type Thrips 5- Lace type Neuroptera 6-Scaly type Lepodoptera 7- Membranous type Hymenoptera 8- Haiteres (Balancers) Diptera Dr.ZAbu-Elnaga
  46. 46. Dr.ZAbu-Elnaga
  47. 47. INSECTMORPHOLOGY Dr.ZAbu-Elnaga
  48. 48. ABDOMINAL REGION & ITS APPENDAGES  It carries paired spiracles laterally  The gonophores postero-ventrally & the anus terminally.  Contraction of abdominal muscles facilitates hatching, molting & oviposition.  In apodous stages it was responsible for locomotion (vermiform movements). Dr.ZAbu-Elnaga
  49. 49. THE ABDOMINAL SEGMENTS  Number: variable, the decrease in number is due to fusion, atrophy, or modification.  Typical structure: a tergite, a starnite & 2 pleurites  Types: distinguished into: 1- Visceral S: constitute the major part of the abdomen next to the thorax (no appendages) 2- Genital S: the subterminal 2 segments carries the gonopore & genitalia (sexual function) 3- Post-Genital (Anal or Caudal) S: the terminal one or 2 segments carry Anus & Cerci (similar in both sexes) Dr.ZAbu-Elnaga
  50. 50. MODIFICATIONS  Structural modifications are common in the genital & caudal segmants. Examples are:  Last tergite in most big insects is split into 3 plates (2 lateral paraprocts & a median epiproct) for anus protection and facilitating egesting  7th sternite in ♀ cockroach, enlarged & boat shaped to protect the genitalia & holds the egg capsule  9th sternum in ♂ cockroach enlarged to protect the genitalia & carries 2 thin sensory processes (Styli)  Last sternum in ♀ lice is clefted to facilitate mating & oviposition  Terminal 3 segments in ♀ house fly reduced to retractile telescoped tubules for oviposition Dr.ZAbu-Elnaga
  51. 51. VISCERAL APPENDAGES • During immature stages some visceral segments carry paired appendages for locomotion or aquatic breathing. In most of them they were disappeared before maturity , but in Collembola they remain • types: 1- Prolegs: Caterpillars (5 pair of prolegs joined the ventral side of 3rd, 4th, 5th, 6th, & 10th abdominal segments , they ends with ring of curved hook-lets for clinging facilitation & climbing. Additionally, they help the thoracic legs but differ from them in position and structure (disappeared in the adult stage) Dr.ZAbu-Elnaga
  52. 52.  Tracheal gills: feather-like lateral extensions of the anterior 7 abdominal segments (May fly nymphs) Dr.ZAbu-Elnaga
  53. 53. SPRINGING APPARATUS Springing apparatus: found in Collmbola, consists of 1- Colliphore (=Adhesor for adhesion) 2-Hamula (Clasper), hold the furcula during repose 3-Furcula (Spring) a long biforked flexible process extending from the latst (5th) segment. Springing takes place as follows a. The fluid is withdrawn from the vesicles of colliphore, then collapse & the insect gets free from substratum b. The furcula is released from the clasper to return backwards in a sudden movement (so, insects springs forwards swiftly) Dr.ZAbu-Elnaga
  54. 54. INSECTMORPHOLOGY Dr.ZAbu-Elnaga
  55. 55. ANAL (CAUDAL) APPENDAGES 1- Cerci: One pair carried by the last segment in both sexes With different shape & size in different insects All of them are tactile in function Caudal gill plates, the terminal segment carries 3 leaf-like thin walled gill plates for aquatic breathing (Damselfly nymphs) Dr.ZAbu-Elnaga
  56. 56. TYPES OF CERCI  Short unsegmented (Locust)  Short, spindle shaped & segmented (cockroach)  Long segmented & setaceous (silverfish)  Forceps-shaped with serrated inner edges (ear-wigs) (for defence & preying) Dr.ZAbu-Elnaga
  57. 57. GENITAL APPENDAGES (GENITALIA) ♂ GENITALIA  Penis: median hollow organ, joining the 9th sternum basally & carrying the ♂ gonopore (copulatory)  claspers: one pair in some insects, enclosing the penis in-between  styli: in cockroaches only, one pair of thin unsegmented process Dr.ZAbu-Elnaga
  58. 58. ♀ GENITALIA (OVIPOSITOR)  8th & 9th segments modified to an egg-laying apparatus (by governing the egg deposition)  Honey bee, cockroach, grasshopper & parasitic wasps  Typical structure: 3 pairs of valves, enclosing the gonopore  Forms of ovipositors: depending on differ in shape & size of valves, for different oviposition habits & other 2ry functions  Function: 1- digging tunnels (Locust)  2- tearing plant leaves (Thrips) 3- piercing & narcotizing (parasitic wasps) 4- defense & attack (honey bees) Dr.ZAbu-Elnaga
  59. 59. FORMS OF OVIPOSITORS Dr.ZAbu-Elnaga
  60. 60. STINGOFHONEYBEE Modified ovipositor In worker only for defense or attack Structure: Dr.ZAbu-Elnaga
  61. 61. Please consider the following in your comments about the course. Would you prefer weekly quizzes rather than the “practice quizzes? Are the listed objectives helpful? Are the study materials helpful? Is the list of terms helpful? The glossary? Are the video clips helpful or distracting? What can I do to improve attendance? Would you recommend the course to a friend? An enemy? Did the course meet your needs now and in future? Were the exams representative of material presented in the course? Would you prefer to have a detailed text book if available at reasonable cost? Please, list any suggestions for improving the course? please, state your accepted skills during studying this course? COURSE EVALUATION Dr.ZAbu-Elnaga
  62. 62. CITATION & REFERENCES 1- Text book of “Fundamentals of applied entomology”. 3rd edition, by Robert E. Pfadt. Macmillan publishing Co., INC. New York, 1971. 2- note book of “Entomology” 2nd year biology, published by the Zoology Dep., Faculty of Science Mansoura University. ovipositors+of+insects&sa=N&start=100&ndsp=20 Comstock-Book/dp/0801481252#reader (honey bee feeding) (house fly ) (mosquito) (cockroach) Recommended Text: The Insects, Structure and Function, by Chapman. Recommended Text: Evolution of the Insects, by Grimaldi and Engel. Recommended Text: Principles of Insect Morphology, by Snodgrass Dr.ZAbu-Elnaga