INTERNAL STRUCTURES OF INSECT

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INTERNAL STRUCTURES OF INSECT
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DIGESTIVE SYSTEM

• Related with i) digestion ii) absorption 3)
  water balance 4) excretion
• Main division 1) foregut
• 2) midgut
• 3) hindgut

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FOREGUT

• Mouth mandibles break down food to small pieces.
  inside mouth salivary glands excrete enzymes to
  1) aid breakdown of food 1) add moisture
• Phariynx region that is circled by muscles
  force food from mouth to esophagus
• Esophagus at tube-like connecting the
  crop(tembolok)

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FOREGUT

• Crop storage area for food. Insect eats beyond
  repletion, so need storage before pushed into
  midgut
• Proventriculus sometimes grinding organ (with
  small teeth sometimes only as a valve between
  fore midgut

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FOREGUT

• MOUTH ? PHARYNX ? ESOPHAGUS

ENZYMES FROM SALIVARY GLANDS
CROP (TEMBOLOK)
PROVENTRICULUS
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MIDGUT

• Ventriculus Enzymes breakdown food chemically,
  initiate nutrient uptake (absorption amino acid,
  carbo, lipids, vit., mineral)
• Single layer epithelial cells, convoluted
  (berlingkar) folded provide absorption space
• The lining is peritrophic membrane 1) as a sieve
  (penapis) which allows enzymes b/down poducts
  to move thru it. 2) protect midgut
• Gastris caeca (sekum gastrik) involved in
  harbouring m/organisms

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Function of midgut??

• 1)
• 2)

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HINDGUT

• Water absorption and waste excretion
• Waste products are concentrated and packaged for
  excretion
• Consists of 1) intestine (ileumcolon) 2)rectum
  3) anus
• From intestine pass to rectal pads further salt
  water retained

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• Malphigian tubules junction of mid hindgut
• Function kidneys of insect absorbs salts, water
  and wastes from the surrounding hemolymph. The
  wastes then are released from the organism in the
  form of solid nitrogenous compounds.
• Waste in form of uric acid (dry and nontoxic)
• Feces Leaf chewing insects very distinctive
  take the shape of the intestine

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• Function
• 1) filter hemolymph
• 2) recover lost metabolites, water salt
• 3) excrete waste
• Ileum?kolon ? rectum? rectum ?anus (waste in form
  of acid uric- dry nontoxic
• T. Malphigian border of mid hindgut

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Insect Nutrition

• Diverse
• Some insects eat variety plants spp. Or maybe
  restricted to single plant
• Eg Manduca sexta eats Solanaceae (tobacco,
  tomato,potatoes)

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What do insects need?

• 1)FAT (LIPID)
• For hormone production
• 2) CARBOHYDRATE(SUGAR)
• For energy
• 3) PROTEINS
• Need amino acid, for development (eg arganine,
  leucine, lysine etc)
• 4) Vitamins
• Vitamin A for vision
• Vit B1 (thiamineenergy),B2 (riboflavinenergy),B6
  (pyridoxineamino acid metabolism)

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RESPIRATORY SYSTEM(TRACHEAL SYS.)

• Gas exchange
• Insect blood doesnt contain haemoglobin
• Has massive plumbing with tubes carry air to
  cells
• GAS (outside)?spiracles? tracheal trunk (pimary
  trachea)? 2o 3o trachea? tracheol

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SPIRACLE

• Air comes thru
• Opening on the body
• Open and close (have muscles) to minimize water
  loss
• Mechanism
• Co2 high in body ?muscles relax ? spricales open
  Co2 escape Oxygen in
• O2 in body approx. outside ? muscles recover ?
  spricales pull shut

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TRACHEAL TRUNK

• Spiral of tough filaments (resist collapse)
• Branches to secondary tertiary trachea
• Smaller tubes tracheols
• Tracheols are intimately associatied with cells
• Eg muscles cells tracheols enter deep into the
  cells close to mitchondria (where o2 needed)
• Or diffuses from tracheols to cells, Co2 from
  tissues to tracheols

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AQUATIC ADAPTATION

• Some without spiracles, they have modified gills
• The gills with thin layer of cuticles with lots
  of tracheoles
• Some have snorkel a tube with spiracles- the
  tube above water for air intake

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CIRCULATORY SYSTEM

• No arteries, veins or capillaries
• The organ sits in open cavity filled with insect
  blood called HEMOLYMPH

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FUNCTIONS

• Transport of nutrient and hormones
• Storage for substance like acid amino
• Water reservoir
• Hydrostatic pressure for movement
• Protection from foreign organism which invade

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HEMOLYMPH

• Consists of
• 1) 90 PLASMA  
• a watery fluid usually clear, sometimes
  greenish or yellowish
• high concentrations of amino acids, proteins,
  sugars, and inorganic ions.  
• 1) 10 HEMOCYTES
• various cell types
• involved in the clotting reaction, phagocytosis,
  and/or encapsulation of foreign bodies.  
• does NOT contain hemoglobin (or red blood cells).
   
• Oxygen is delivered by the tracheal system, not
  the circulatory system.

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DORSAL VESSELS (SALUR DARAH)

• HEART
• divided segmentally into chambers
• that are separated by valves (ostia) to ensure
  one-way flow of hemolymph.  
• A pair of alary muscles are attached laterally to
  the walls of each chamber.  
• Peristalsis these muscles force the hemolymph
  forward from chamber to chamber

• AORTA
• In front of the heart,
• lacks valves or muscle.  
• continues forward to the head and empties near
  the brain.  
• Hemolymph bathes the organs and muscles of the
  head as it emerges from the aorta
• then back over the alimentary canal,through the
  body until it reaches the abdomen and re-enters
  the heart.

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PERICARDIAL SINUS
DORSAL DIAPHRAGM
PERIVISCERAL SINUS
PERINEURAL SINUS
VENTRAL DIAPHRAGM
To facilitate circulation of hemolymph, the body
cavity is divided into three compartments
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REMEMBER!!!!

• DOES NOT CARRY OXYGEN!!!
• So blood flow is not critical like us human

HEMOLYMPH FROM BODY?ENTER OSTIA( HEART MUSCLE
RELAX?PERISTALSIS
MOVE FORWARD CHAMBERS
AORTA (LACK MUSCLES VALVE)
BATHES HEAD AND ALL ORGANS BACK TO ABDOMEN
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SENSORY SYSTEM

• Exoskeleton need sensory organ
• To evaluate changes in the environment
• First info receive by SENSILLA specialized
  cuticullar structure equipped with nerve cells
  and neuron
• Usually hair-like

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PHOTORECEPTOR

• Light/vision
• Vision can be restricted in insects
• Some to differentiate light from dark
• Some can distingusih shape images
• 3 types of photoreceptor
• 1) ocelli
• 2)stemmata
• 3) compound eye

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OCELLI

• Many adults and nymph of hemimetabolous
• Related to flight, most flightless insects dont
  have
• Sensitive to light intensity
• Cannot perceive images or shape

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STEMMATA

• Only on larvae of holometabolous
• Larvae of holometabolous almost never have
  compound eyes
• capable only of detecting light.
• cannot focus or allow reception of images.

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COMPOUND EYES

• Consists of numerous hexagon shaped facets/lense
  called ommatidium
• 2 major components 1) lenses 2) light receiving
  syst.

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MECHANISM

• Lens guide light to a group of pencil-shaped like
  cells tie up together called rhabdom
• These photoreceptor absorp the light then convert
  to eletrical signal which is conveyed in brain
• RHODOPSIN chemical pigment to absorb light, with
  the help of Vitamin A

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• Insect eyes cannot focus until sharp image
• The best insect eye resolves less detail than
  human eye
• But sensitive in movement
• So what they perceive ? Shape form
• Broken shapes are differentiated solid

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• Some can see colours
• Pigments in ommatidia sensitive to different
  array of colours
• Insect sees from 700 nm (red) range down to 3o0
  (violet)
• Bees see flower blue

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CHEMORECEPTOR

• Smell/taste (olfaction)
• Well developed compared to photoreceptor
• A) Close range,
• chemical signals in solution form (taste)
• Found in legs
• Eg honeybee taste sweet, sour, salty and bitter
• Eg red admiral butterfly 200x sensitive to sugar
  than hman tongue

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CHEMORECEPTOR

• B) distant range (jarak jauh)
• Airborne chemical signal smell
• Found on antennae
• detect odours great distance, miles
• Useful for finding mates
• PHEROMONES chemical signals
• Smells much more sensitive than human

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MECHANORECEPTOR

• Touch/pressure/vibration or sound
• Sense of pressure/touch usually on legs often
  contact to ground
• Many insects are deaf sound not really important
• Tympanum on legs for cricket, on abdomen for
  cicadas
• Hair sensilla in antenna eg Johnstons organ

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THERMORECEPTOR

• Changes in temperature
• Bed bug use thermoreceptor to locate warm blooded
  verteb.

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HYGRORECEPTOR

• changes of humidity
• Blood feeding parasites
• Warm, moist breath good indicator of host

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NERVOUS SYSTEM

• INSECT SIMPLE CREATURE????
• What happen when you attack the fly?????
• 3 components
• 1)brain central
• 2)ventral nerve cord nervous system
  (CNS)
• 3)peripheral nervous system (extend outside the
  central nervos system to serve the limbs and
  organs
• Each of the components consists millions of
  neurons

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VENTRAL NERVE CORD
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WHAT IS NEURON?

• Nerve cell
• For information transfer
• Composed of
• 1) dendrite (enter the cell body)
• 2) cell body (nucleus found)
• 3) axon( leaving the body)
• Repeating unit of neuron form a nervous system
• Individual nerve cells connect with one another
  through special junctions, called synapses.

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• 3 categories, depending on their function within
  the nervous system
• 1) Afferent (sensory) neurons
• bipolar or multipolar cells
• dendrites associated with sense organs or
  receptors.  
• carry information toward the central nervous
  system.

A
D
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• 2) Efferent (motor) neurons
• unipolar cells
• conduct signals away from the central nervous
  system
• stimulate responses in muscles and glands.

A
D
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• 3) Interneurons
• unipolar cells (often with several collaterals
  and/or branching axons) that conduct signals
  within the central nervous system.

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BRAIN

• Nerve cord to the head is the BRAIN
• 3 pairs of ganglia region
• 1)protocerebrum associated with vision they
  innervate the compound eyes and ocelli.
  2)deotocerebrum pair lobes with sensory
  pathway to antennae
• 3)tritocerebrum lobes with connective to 1st
  ganglion of ventral nerve cord

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VENTRAL NERVE CORD

• 1) subesophageal ganglion
• innervates mandibles, maxillae, and labium,
  hypopharynx, salivary glands, and neck muscles.
• 2) thoracic ganglia
• ) control locomotion by innervating the legs and
  wings.
• 3) abdominal ganglia
• control movements of abdominal muscles.

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PERIPHERAL NERVOUS SYSTEM

• 1) neuron of sensory organs (sensory neuron)
• 2) neuron attached to muscles (motor neuron)
• Function of insect nervous syst critical in
  insect control

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REPRODUCTIVE SYSTEM

• Reproduce 1) SEXUALLY 2) ASEXUALLY
• Mosy sexually
• 2 sex cells
• 1) sperm 2) ovum

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MALE REPRODUCTIVE SYSTEM
A

• Sperm produce by testes (A)
• From testes sperm stored in
  seminal
  vesicle (B)
• During copulation discharge
  thru aedeagus
  (C) (penis) along with
  secretion from accessory glands (D)

D
B
C
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FEMALE REPRODUCTIVE SYSTEM

• Ovum produce by OVARY (A)
• Inside ovaries OVARIOLES (B)
  egg
  producing tubules
• SPERMATHECA (C) storing sperm
  -sp. That mate once stored sperm
  for months/years
• ACCESSORY GLANDS (D) provide
  materials for egg to attach to substrate

A
B
D
C
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ASEXUAL REPRODUCTION

• Benefit
• Rapid increase in number
• Close match between organism environment
• Save time dont have ti find and court mate
• Disadvantage offspring (anak) not variable
• 3 modes(cara)
• 1) HERMAPHRODISM egg sperm produce by same
  individual
• 2) GYNOGENESIS egg is activated by the presence
  of sperm in order to develop. However, the sperm
  cell does not contribute any genetic material to
  the offspring.
• 3) PARTHENOGENESIS reproduction without
  fertilization (persenyawaan)

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PARTHENOGENESIS

• 1) ARRHENOTOKY
• unfertilised eggs develop into males
• Bees, ants, wasps
• 2) THELYTOKY
• Unfertilized eggs turn to female
• aphid

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EGG LAYING

• use ovipositor
• variaton
• long, tubular- sticking eggs into hard suface
• Long-horned grasshopper, parasitic wasp
• Some are short

6-7 cm
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• Eggs hatch to produce larva/nymph
• METAMORPHOSIS
• 1) AMETABOLOUS
• Without metamorphosis or unclear
• Silverfish (Thysanura)
• 2) HEMIMETABOLOUS (EXOPTERYGOTA)
• Incomplete m/morphosis (egg?nymph/naiad?adult)
• a) Paurometabolous the nymph and the adult would
  live in the same environment (grasshopper,cricket)
  
• b) Heterometabolous the nymph adult live in
  different environments. For example, Odonata
  naiad live in the water and cicada nymph
  underground, whereas the adults are aerial.
• 3) HOLOMETABOLOUS (ENDOPTERYGOTA)
• Complete m/morphosis (egg?larva?pupa?adult)

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