Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
L . 2 . Medical Entomology M.S.C. IZDIHAR A. ALWAN Class :- Insecta A look at the outside of an insect : Exoskeleton As typical arthropods , insects have a chitinous cuticle secreted by the hypodermis , a single layer of columnar epithelial cells of ectodermal origin which is cast off or molted at intervals to permit growth and metamorphosis . The chitinous cuticle serves as an exoskeleton (integument ) , thus as both a body covering and a place for attachment of muscles . Heavily chitinized areas or plates of cuticle are connected by thinner lightly chitinized areas , thus permitting movement and some degree of expansion as , for example when the abdomen of a feeding female mosquito fills with blood . Insect muscles are striated and often capable of extraordinarily rapid contraction . The cuticle consist of three layers are Endocuticle , Exocuticle and Epicuticle which is impermeable to water . When a developing insect has grown too large for its cuticle , the hypodermis lays down a new , thin , elastic cuticle under the old one . The cuticle then splits and the insect emerges from it , this process termed molting or ecdysis . Body division of insects :1- The Insect Head : * Mouthparts Labrum ( 1 ) " Upper lip " , Mandibles ( 2 ) " Jaws " , Maxillae ( 2 ) " More jaws " , labium ( 1 ) " Lower lip " and Hypopharynx ( 1 ) " Tongue – like , bears openings of salivary ducts " Different arrangements and forms of these parts makeup the principal types of insects mouths :1 Chewing mouth parts :. It seems that this is the most primitive type of mouth parts . Cockroaches , beetles and chewing lice are examples for this type . Sponging mouth parts : found in large numbers of the non- biting flies such as the house flies and flesh flies have this type of mouth parts . Piercing – sucking mouth parts : are possessed by insects such as mosquitoes , assassin bugs , stable flies , sucking lice and fleas . these insects pierce the skin of animals in order to suck the blood from them . These mouth parts are characteristic of most the insect vectors of disease . Cutting – lapping mouth parts : This is restricted to a limited number of adult flies feeding as parasites up on blood from mammal hosts . Black flies and horse flies are good examples . Siphoning mouth parts :- The mandibles and labium are reduced or lost and have no role in food ingestion , this type found in butterfly Chewing – lapping mouth parts : adult hony bees and bumble bees have mouth parts that are modified in still another form in order to utilize liquid food in this case nectar and honey . * Eyes : Compound eyes : individual units are facets or ommatidia 28000 ommatidia Simple eyes " Ocelli " : small and usually a single lens . * Antennae : Two basal segments are the scape and pedicel . The filament is comprised of several segments ( actually pseudo-segments lacking independent musculature ) . 2 Types of Antennae a- Setaceous : hair – like ( Cockroach ) . b- Filiforn : thread – like (Grasshopper ) . c- Moniliform : bead – like ( Termites ) . d- Serrate : sawtoothed ( beetles ) . e- Pectinate : comb – like ( moth and beetles ) , Bipectinate ( Bombyx mori ) . g- Capitate : head – like , less enlarged at the tip would be clublike ( Tenebrio ) . h- Geniculate : elbowed ( honey bee ) . i- lamellate : plate – like ( beetles ) . j- Plumose : feather – like ( male mosquite ) , pilose ( female mosquite ) . k- Stylate ( horse fly ) . l- Aristate ( house fly ) . m- Clavate ( Butterflies ) 3 2- The insect thorax : three distinct segments :Prothorax : bears 1 pair of legs . Mesothorax : bears 1 pair of legs , 1 pair of wings . Metathorax : bears 1 pair of legs , 1 pair of wings . * Legs : are segmented , the names for each segment are :- coxa , trochanter , femur , tibia and tarsus . The tarsus may be comprised of multiple segments the terminal segment usually bears claws . Legs may be modified for specific purposes :Jumping : ( grasshoppers , fleas ) . Running " walking " : ( ground beetles , cockroaches ) . Clinging : ( lice ) . Grasping " manting " : ( giant water bugs , mantis ) . Digging : ( mole – cricket ) . Swimming : ( water beetle ) . Cleaning legs and Collecting legs : ( honey bee ) . * Wings : Mesothoracic wing = forewing , Metathoracic wing = hindwing . wing veins and cells between veins are named according to the standared system illustrated below : Wing modifictions :Halteres ( halter ) : knob – like reduced hind wings of Diptera . Elytra ( elytron ) : Hardened , protective forewings of Coleoptera . Hemielytra : Half – hardened , Half – membranous forewings of Hemiptera . Hairy wings : modified wing structure of the Thysanoptera ( Thrips ) . Scaly wings : Lepidoptera and some Diptera . Tegmina (Leathery) wing : cockroaches and grasshoppers. Membranous wing : Hony bee and Wasp . 3- The insect abdomen : The abdomen consist of 11 or fewer segments , of which the terminal ones are modified * Reproductive appendages Male genitalia and Ovipositor : egg laying apparatus ( may be modified for other purposes ) . * Non- reproductive appendages Caudal fillament , Anal styli and Anal cerci . 4