Insect Structure. Why Study? An understanding of the external structure of the An understanding of the external structure of the insect is necessary…

Insect StructureInsect Structure

Why Study? Why Study? • An understanding of the external structure An understanding of the external structure of the of the insect is necessary…insect is necessary…

- to allow the identification of insects and - to allow the identification of insects and other arthropodsother arthropods

- to understand their biology and control- to understand their biology and control

ExoskeletonExoskeleton

• Outer layer or “skin”Outer layer or “skin”

• Functions:Functions: - Protection of soft parts- Protection of soft parts - Muscle attachment- Muscle attachment - Support- Support - Site for sensory organs- Site for sensory organs - Helps prevent desiccation- Helps prevent desiccation - Reduces pathogen entry- Reduces pathogen entry

Components of the Components of the ExoskeletonExoskeleton

• CuticleCuticle - non-living- non-living

• EpidermisEpidermis- living- living- secretes the cuticle- secretes the cuticle

• Basement membraneBasement membrane- non-living- non-living- function not known- function not known

CuticleCuticle• Key contributor to the success of insectsKey contributor to the success of insects

- barrier between living tissue/environment- barrier between living tissue/environment- restriction of water loss- restriction of water loss- abrasion protection- abrasion protection

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exocuticle

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Body StructureBody Structure

3 body regions 3 body regions

1 pair of antennae1 pair of antennae

3 pair of legs on the thorax3 pair of legs on the thorax

HeadHead

ThoraxThorax

AbdomenAbdomen

HeadHead• Functions:Functions:

- Mouthparts (feeding appendages)- Mouthparts (feeding appendages)

- Sensory organs (interaction with nature)- Sensory organs (interaction with nature)

- photoreceptors/vision- photoreceptors/vision- receptors on antennae- receptors on antennae

- Houses the brain- Houses the brain

AntennaeAntennae

• Single pair Single pair

• Located between and in front of eyesLocated between and in front of eyes

• Sensory function Sensory function - touch- touch- smell- smell- humidity- humidity- sound- sound

AntennaeAntennae• TypesTypes

VisionVision

• Compound eyes Compound eyes - main organ of vision- main organ of vision

• Composed of individual units - ommatidia Composed of individual units - ommatidia - each registers a portion of a mosaic image- each registers a portion of a mosaic image- number vary (>25,000 for dragonflies)- number vary (>25,000 for dragonflies)- surface of eye is protected with a cuticle- surface of eye is protected with a cuticle

• Resolution of image variesResolution of image varies

- dragonfly: several meters away- dragonfly: several meters away- other insects: only a meter or so away- other insects: only a meter or so away

How do insects perceive How do insects perceive the world?the world?

• Many can see color (but many blind to red)Many can see color (but many blind to red)

• Others see colors we can not - UltravioletOthers see colors we can not - Ultraviolet

• Some only detect degrees of light and no imageSome only detect degrees of light and no image

• Others are totally blindOthers are totally blind

Nectar GuidesNectar Guides

• Many insect-pollinated flowers have nectar Many insect-pollinated flowers have nectar guidesguides

• Serve as visual guides to direct insects to nectar Serve as visual guides to direct insects to nectar sourcesource

• Nectar guides absorb UV lightNectar guides absorb UV light

• Rest of flower reflects UV lightRest of flower reflects UV light

MouthpartsMouthparts

• Basic types:Basic types:

- chewing- chewing - sponging- sponging- piercing-sucking- piercing-sucking - siphoning- siphoning- rasping-sucking- rasping-sucking - chewing-lapping- chewing-lapping

• Important for insect identificationImportant for insect identification

• Provides information on feeding habits Provides information on feeding habits and types of damageand types of damage

Chewing TypeChewing Type• Simplest typeSimplest type

• Used to chew holes in leaves, bore in stemsUsed to chew holes in leaves, bore in stems

• Examples: grasshoppers, crickets, Examples: grasshoppers, crickets, caterpillars, beetlescaterpillars, beetles

Piercing-Sucking TypePiercing-Sucking Type

• Common and important typeCommon and important type

• Greatly modified for puncturing Greatly modified for puncturing plants and animalsplants and animals

• Mouthpart components form needle-like styletsMouthpart components form needle-like stylets

• Capable of transmitting virusesCapable of transmitting viruses

• Toxic salivaToxic saliva

• Examples: mosquitoes, stink bugs, etc.Examples: mosquitoes, stink bugs, etc.

Rasping-Sucking TypeRasping-Sucking Type

• Combination of chewing and piercing-suckingCombination of chewing and piercing-sucking

• Rasp (scrap) surfaces of leave, suck up sapRasp (scrap) surfaces of leave, suck up sap

• Example: thripsExample: thrips

Sponging TypeSponging Type

• Modified for liquids or solid foodsModified for liquids or solid foods- solid foods must be dissolved by salivary - solid foods must be dissolved by salivary secretionssecretions

• Example: house flyExample: house fly

Siphoning TypeSiphoning Type• Mouthparts form a sucking tube (proboscis)Mouthparts form a sucking tube (proboscis)

- modified for uptake of nectar/liquids- modified for uptake of nectar/liquids

• Coiled beneath head when not in useCoiled beneath head when not in use

• Examples: butterflies and mothsExamples: butterflies and moths

Chewing-Lapping TypeChewing-Lapping Type

• Modified to use liquid or semi-liquid foodsModified to use liquid or semi-liquid foods

• Some mouthpart components function for chewingSome mouthpart components function for chewing- mold wax- mold wax- grasping prey- grasping prey- cutting flowers- cutting flowers

• Other components form the proboscisOther components form the proboscis- ‘lapping’ surface- ‘lapping’ surface

• Examples: honey bee, bumble beeExamples: honey bee, bumble bee

ThoraxThorax

• Divided into 3 regionsDivided into 3 regions- prothorax- prothorax- mesothorax- mesothorax- metathorax- metathorax

• Main function: locomotionMain function: locomotion - walking/running- walking/running - jumping- jumping - swimming- swimming - flying- flying

LegsLegs

• Three pairs of true legsThree pairs of true legs

• 6 basic segments of the leg6 basic segments of the leg- coxa- coxa- trochanter- trochanter- femur- femur- tibia- tibia- tarsus- tarsus- pretarsus- pretarsus

• Adapted for various functionsAdapted for various functions

Types of LegsTypes of Legs

• Cursorial – runningCursorial – running

• Fossorial – diggingFossorial – digging

• Raptorial – predaceousRaptorial – predaceous

• Saltatorial – jumpingSaltatorial – jumping

• Natatorial - swimmingNatatorial - swimming

WingsWings

• Number of wings varies by speciesNumber of wings varies by species- 2 pairs - 2 pairs - 1 pair on the mesothorax- 1 pair on the mesothorax- absent- absent

• FunctionsFunctions - locomotion- locomotion - protection- protection - camaflouge- camaflouge

Types of WingsTypes of Wings• MembranousMembranous

• Elytra - Elytra - hardened, front wings hardened, front wings that serve as protective covers that serve as protective covers for membranous hind wings for membranous hind wings

• Hemelytra - Hemelytra - front wings that are front wings that are leathery or parchment- leathery or parchment- like at the base and like at the base and membranous near the tip membranous near the tip

• Halteres - Halteres - small, club-like hind wings small, club-like hind wings that serve as gyroscopic that serve as gyroscopic stabilizers during flight stabilizers during flight

• ScalesScales

• Tegmina - Tegmina - front wings that are front wings that are completely leathery or completely leathery or parchment-like in texture parchment-like in texture

AbdomenAbdomen• Functions:Functions:

- respiration- respiration

- excretion- excretion

- reproduction- reproduction

AbdomenAbdomen• SpiraclesSpiracles

- openings involved in respiration- openings involved in respiration

- located on each side of abdomen- located on each side of abdomen

• CerciCerci - sensory organs- sensory organs

• OvipositorOvipositor - egg-laying structure- egg-laying structure - stingers (modified ovipositor- stingers (modified ovipositor

found in some females)found in some females)

That’s All!!!That’s All!!!