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INTERNAL STRUCTURES OF INSECT DIGESTIVE SYSTEM Related with i) digestion; ii) absorption; 3) water balance; 4) excretion Main division: 1) foregut 2) midgut 3) hindgut 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) 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 FOREGUT MOUTH PHARYNX ESOPHAGUS ENZYMES FROM SALIVARY GLANDS CROP (TEMBOLOK) PROVENTRICULUS 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 Function of midgut?? 1) 2) HINDGUT Water absorption and waste excretion Waste products are concentrated and packaged for excretion Consists of 1) intestine (ileum+colon); 2)rectum; 3) anus From intestine pass to rectal pads: further salt & water retained 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 Function: 1) filter hemolymph 2) recover lost metabolites, water & salt 3) excrete waste Ileumkolon rectum rectum anus (waste in form of acid uric- dry & nontoxic T. Malphigian border of mid & hindgut Insect Nutrition Diverse Some insects eat variety plants spp. Or maybe restricted to single plant Eg: Manduca sexta: eats Solanaceae (tobacco, tomato,potatoes) What do insects need? 1)FAT (=LIPID) 2) CARBOHYDRATE(SUGAR) For energy 3) PROTEINS For hormone production Need amino acid, for development (eg arganine, leucine, lysine etc) 4) Vitamins Vitamin A for vision Vit B1 (thiamine:energy),B2 (riboflavin:energy),B6(pyridoxine:amino acid metabolism) RESPIRATORY SYSTEM(TRACHEAL SYS.) Gas exchange Insect blood doesn’t contain haemoglobin Has massive plumbing with tubes carry air to cells GAS (outside)spiracles tracheal trunk (pimary trachea) 2o & 3o trachea tracheol 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 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 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 CIRCULATORY SYSTEM No arteries, veins or capillaries The organ sits in open cavity filled with insect blood called ‘HEMOLYMPH’ FUNCTIONS Transport of nutrient and hormones Storage for substance like acid amino Water reservoir Hydrostatic pressure for movement Protection from foreign organism which invade 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. DORSAL VESSELS (SALUR DARAH) 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 reenters the heart. 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 PERICARDIAL SINUS DORSAL DIAPHRAGM PERIVISCERAL SINUS PERINEURAL SINUS VENTRAL DIAPHRAGM To facilitate circulation of hemolymph, the body cavity is divided into three compartments: REMEMBER!!!! DOES NOT CARRY OXYGEN!!! So blood flow is not critical like us human HEMOLYMPH FROM BODYENTER OSTIA( HEART MUSCLE RELAXPERISTALSIS BATHES HEAD AND ALL ORGANS & BACK TO ABDOMEN AORTA (LACK MUSCLES & VALVE) MOVE FORWARD CHAMBERS 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 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 OCELLI Many adults and nymph of hemimetabolous Related to flight, most flightless insects don’t have Sensitive to light intensity Cannot perceive images or shape 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. COMPOUND EYES Consists of numerous hexagon shaped facets/lense called ommatidium 2 major components: 1) lenses; 2) light receiving syst. 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 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 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 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 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 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 Johnston’s organ THERMORECEPTOR Changes in temperature Bed bug use thermoreceptor to locate warm blooded verteb. HYGRORECEPTOR changes of humidity Blood feeding parasites Warm, moist breath good indicator of host 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 VENTRAL NERVE CORD 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. 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 2) Efferent (motor) neurons unipolar cells conduct signals away from the central nervous system stimulate responses in muscles and glands. A D 3) Interneurons unipolar cells (often with several collaterals and/or branching axons) that conduct signals within the central nervous system. 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 VENTRAL NERVE CORD 1) subesophageal ganglion 2) thoracic ganglia innervates mandibles, maxillae, and labium, hypopharynx, salivary glands, and neck muscles. ) control locomotion by innervating the legs and wings. 3) abdominal ganglia control movements of abdominal muscles. 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 REPRODUCTIVE SYSTEM Reproduce: 1) SEXUALLY 2) ASEXUALLY Mosy sexually 2 sex cells 1) sperm 2) ovum MALE REPRODUCTIVE SYSTEM 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) A D B C FEMALE REPRODUCTIVE SYSTEM Ovum produce by OVARY (A) Inside ovaries: OVARIOLES (B) A 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 B D C ASEXUAL REPRODUCTION Benefit: Rapid increase in number Close match between organism & environment Save time: don’t 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) PARTHENOGENESIS 1) ARRHENOTOKY unfertilised eggs develop into males Bees, ants, wasps 2) THELYTOKY Unfertilized eggs turn to female aphid EGG LAYING use ovipositor variaton: long, tubular- sticking eggs into hard suface Long-horned grasshopper, parasitic wasp Some are short ♀ ovipositor 6-7 cm Eggs hatch to produce larva/nymph METAMORPHOSIS: 1) AMETABOLOUS Without metamorphosis or unclear Silverfish (Thysanura) 2) HEMIMETABOLOUS (EXOPTERYGOTA) Incomplete m/morphosis (eggnymph/naiadadult) 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 (egglarvapupaadult)