Insect Structure Why Study? вЂў An understanding of the external structure of the insect is necessaryвЂ¦ - to allow the identification of insects and other arthropods - to understand their biology and control Exoskeleton вЂў Outer layer or вЂњskinвЂќ вЂў Functions: - Protection of soft parts - Muscle attachment - Support - Site for sensory organs - Helps prevent desiccation - Reduces pathogen entry Components of the Exoskeleton вЂў Cuticle - non-living вЂў Epidermis - living - secretes the cuticle вЂў Basement membrane - non-living - function not known Cuticle cement wax exocuticle endocuticle cuticle epicuticle вЂў Key contributor to the success of insects - barrier between living tissue/environment - restriction of water loss - abrasion protection Body Structure п‚§ 3 body regions Head Thorax Abdomen п‚§ 1 pair of antennae п‚§ 3 pair of legs on the thorax Head вЂў Functions: - Mouthparts (feeding appendages) - Sensory organs (interaction with nature) - photoreceptors/vision - receptors on antennae - Houses the brain Antennae вЂў Single pair вЂў Located between and in front of eyes вЂў Sensory function - touch - smell - humidity - sound Antennae вЂў Types Vision вЂў Compound eyes - main organ of vision вЂў Composed of individual units - ommatidia - each registers a portion of a mosaic image - number vary (>25,000 for dragonflies) - surface of eye is protected with a cuticle вЂў Resolution of image varies - dragonfly: several meters away - other insects: only a meter or so away How do insects perceive the world? вЂў Many can see color (but many blind to red) вЂў Others see colors we can not - Ultraviolet вЂў Some only detect degrees of light and no image вЂў Others are totally blind Nectar Guides вЂў Many insect-pollinated flowers have nectar guides вЂў Serve as visual guides to direct insects to nectar source вЂў Nectar guides absorb UV light вЂў Rest of flower reflects UV light Mouthparts вЂў Basic types: - chewing - sponging - piercing-sucking - siphoning - rasping-sucking - chewing-lapping вЂў Important for insect identification вЂў Provides information on feeding habits and types of damage Chewing Type вЂў Simplest type вЂў Used to chew holes in leaves, bore in stems вЂў Examples: grasshoppers, crickets, caterpillars, beetles Piercing-Sucking Type вЂў Common and important type вЂў Greatly modified for puncturing plants and animals вЂў Mouthpart components form needle-like stylets вЂў Capable of transmitting viruses вЂў Toxic saliva вЂў Examples: mosquitoes, stink bugs, etc. Rasping-Sucking Type вЂў Combination of chewing and piercing-sucking вЂў Rasp (scrap) surfaces of leave, suck up sap вЂў Example: thrips Sponging Type вЂў Modified for liquids or solid foods - solid foods must be dissolved by salivary secretions вЂў Example: house fly Siphoning Type вЂў Mouthparts form a sucking tube (proboscis) - modified for uptake of nectar/liquids вЂў Coiled beneath head when not in use вЂў Examples: butterflies and moths Chewing-Lapping Type вЂў Modified to use liquid or semi-liquid foods вЂў Some mouthpart components function for chewing - mold wax - grasping prey - cutting flowers вЂў Other components form the proboscis - вЂ�lappingвЂ™ surface вЂў Examples: honey bee, bumble bee Thorax вЂў Divided into 3 regions - prothorax - mesothorax - metathorax вЂў Main function: locomotion - walking/running - jumping - swimming - flying Legs вЂў Three pairs of true legs вЂў 6 basic segments of the leg - coxa - trochanter - femur - tibia - tarsus - pretarsus вЂў Adapted for various functions Types of Legs вЂў Cursorial вЂ“ running вЂў Fossorial вЂ“ digging вЂў Raptorial вЂ“ predaceous вЂў Saltatorial вЂ“ jumping вЂў Natatorial - swimming Wings вЂў Number of wings varies by species - 2 pairs - 1 pair on the mesothorax - absent вЂў Functions - locomotion - protection - camaflouge Types of Wings вЂў Membranous вЂў Elytra - hardened, front wings that serve as protective covers for membranous hind wings вЂў Hemelytra - front wings that are leathery or parchmentlike at the base and membranous near the tip вЂў Halteres - small, club-like hind wings that serve as gyroscopic stabilizers during flight вЂў Scales вЂў Tegmina - front wings that are completely leathery or parchment-like in texture Abdomen вЂў Functions: - respiration - excretion - reproduction Abdomen вЂў Spiracles - openings involved in respiration - located on each side of abdomen вЂў Cerci - sensory organs вЂў Ovipositor - egg-laying structure - stingers (modified ovipositor found in some females) ThatвЂ™s All!!!