Insect Morphology 2 PDF

INSECT z MORPHOLOGY CROP PROT 101 z z INSECT MORPHOLOGY  General Characteristics of Insects z ▪ three body regions “tagmata” (head, thorax and abdomen) ▪ a pair of antennae ▪ three thoracic segments each bearing a pair of legs ▪ meso and metathorax usually bears a pair of...

INSECT z MORPHOLOGY CROP PROT 101 z z INSECT MORPHOLOGY  General Characteristics of Insects z ▪ three body regions “tagmata” (head, thorax and abdomen) ▪ a pair of antennae ▪ three thoracic segments each bearing a pair of legs ▪ meso and metathorax usually bears a pair of wings ▪ paired appendages z Integument System ▪ also insect exoskeleton ▪ largest among the organ systems ▪ exhibits the greatest diversity in function and structure ▪ said to be responsible for the success of the insects as terrestrial animals  z Functions of Integument System ▪ Outer covering ▪ Framework for muscle attachment ▪ Rigid leverage for muscles ▪ Provides external structure for sensory perception ▪ Role in reproduction, feeding, and other physiological processes ▪ Site for respiration ▪ Provides information for taxonomical purposes Structure of the Insect Integument z cuticle + epidermis + basement membrane CUTICLE ▪ non-cellular / non-living layer ▪ three layers ✓ Epicuticle : cement, wax, cuticulin, homogenous cuticle ✓ Exocuticle : exuvia PROCUTICLE ✓ Endocuticle : arthropodin and chitin Structure of the Insect Integument z EPIDERMIS ▪ cellular / living layer ▪ secretes molting fluid BASEMENT MEMBRANE ▪ separates epidermis from body cavity z Chemical Composition of Integument z z INSECT HEAD z INSECT HEAD ▪ anterior, hard capsule-like body region (eyes, antennae and mouthparts); ▪ heavily sclerotized ▪ Compound eye – it is a visual organ that consists of single units called ommatidia ▪ It distinguishes brightness and color ▪ Ocelli– there are 3 ocelli found in the head arranged in isosceles triangle - used to detect movement z Structures of Insect Head OCELLI (us) COMPOUND EYES ▪ simple eyes ▪ consists of ommatidia ▪ consists of one corneal lens ▪ forms image ▪ maximum number : 3 ✓ Holoptic – when the compound eyes meet in the middle ▪ perceive light ✓ Dichoptic - when the compound eyes are separated  z Types of Head Orientation Prognathous Hypognathous Opisthognathous or (Greek: pro- ‘forward’; (Greek: hypo- under; opisthorrhynchous = gnathous – ‘jaw’) gnathous – ‘jaw’) (Greek: opisthos – behind; mouthparts are directed mouthparts are gnathous- ‘jaw’) forward directed downward mouthparts are directed in posterior ventral position z Types of Head Orientation PROGNATHOUS ▪ mouthparts directed forward ▪ predators, carnivorous, endo parasitic, wood borers, and miners ▪ i.e. antlion, tiger beetle, dragonfly z Types of Head Orientation HYPOGNATHOUS ▪ mouthparts in continuous series with the legs ▪ phytophagous insect ▪ mouthparts parallel to the body ▪ i.e. grasshopper z Types of Head Orientation OPISTOGNATHOUS ▪ mouthparts directed posteriorly between the front legs ▪ piercing-sucking insects ▪ i.e. aphids, leafhoppers, cicada z Appendages of the Head 1. ANTENNAE ▪ major sensory organ ©Sciencelearn.org ▪ PARTS: ✓ Scape – 1ST segment of the antenna that articulates with the head capsule ✓ Pedicel – 2nd segment that contains the Johnstons’s organ ✓ Flagella – the rest of the segments which is composed of flagellomeres z Structure of Antenna z Types Description e. g. z PECTINATE Most segments with ♂ giant click (comb-like) long, slender lateral beetle; male processes glow-worms; fire-colored beetles BIPECTINATE Atlas moth (double comb- like) CLAVATE Increase in size of Butterfly (club-shaped) segments is gradual GENICULATE First segment long, Ants (elbowed) following segments small and going-off at an angle to the first Types z Description e.g. Plumose Segments with whorls of long Male hairs mosquito Lamellate Nestled plates Scarab beetle Aristate Last segment usually enlarged Houseflies (Pouch-like w/ and bearing a conspicuous Syrphid flies usually dorsal arista bristle) Stylate Last segment bearing an Robber flies elongate terminal finger-like process called style  z Types of Insect Antennae FILIFORM SETACEOUS CLAVATE MONILIFORM LAMELLATE ARISTATE thread-like bristle / needle-like club-like bead-like leaf / plate-like Pouch-like i.e. grasshopper i.e. dragonfly i.e. butterflies i.e. termites i.e. scarab beetles i.e. houseflies SERRATE PECTINATE BIPECTINATE PLUMOSE GENICULATE saw-toothed comb-like double comb-like hair / feather-like elbow / L – like antenna i.e click beetles i.e. net winged beetle i.e. male atlas moth i.e. male mosquito i.e. honeybee , wasps, ants  z Appendages of the Head 2. MOUTHPARTS ▪ Labrum ✓ “upper lip” ✓ holds / pull food to the mouth, it moves longitudinally ▪ Mandible ▪ Labium ✓ “lower lip” ✓ “upper jaw” ✓ cut / tear / chew food ✓ close the mouth below or behind, ▪ Maxillae ✓ Possess segmented palps ✓ “lower jaw” which are sensory ✓ Behind the mandible that manipulate food ▪ Hypopharynx ✓ accessory jaws ✓ Tongue-like process that helps mix food and saliva z Types of Mouthparts  z Types of Mouthparts Types Description e. g. CHEWING/ Most generalized condition; with heavily Grasshopper MANDIBULATE sclerotized mandibles that move sideways and (most generalized) can bite off and chew particles of food PIERCING- Presence of a tubular, usually jointed beak Bugs SUCKING enclosing several needle-like stylets RASPING- Characterized by a short stout, assymetrical Thrips SUCKING conical structure located ventrally at the rear of the head; 3 stylets  z Types of Mouthparts Types Description e. g. SIPHONING Galea of maxillae greatly elongated and joined Butterfly to form a slender hallow tube which is coiled up under the head when not in use (proboscis) SPONGING End of labium specialized into a sponge-like flies organ (labellum) CHEWING- Mandibles and labrum are of the chewing type Bees LAPPING and used for grasping prey or molding wax or nest material; maxilla and labium developed into a series of flattened elongate structure used to probe deep into blossoms (flabellum)  z Types of Mouthparts CHEWING / MANDIBULATE PIERCING - SUCKING SPONGING SIPHONING strong mandibles needle – like mouthpart labial tip modified into a mouthpart modified into feeds on solid food feed on liquid sponge (labella) coiled proboscis (i.e. plant sap, blood) feeds on soluble solids feeds on liquids (i.e. nectar) (i.e. sugar)  z Types of Mouthparts RASPING-SUCKING CHEWING-LAPPING clypeus, labrum, parts of maxillae and mandible and labrum mandibulate labium fused to form a beak maxilla shrunken mandible asymmetrical (left) labium developed into large tongue feeds on liquids (i.e. plant sap) (glossa) example : thrips feeds on nectar and pollen example: honeybees, wasps z z INSECT THORAX  z The THORAX ▪ For locomotion, walking and flight ▪ Three segments: ▪ composed of three plates ▪ Prothorax Each of the segments ✓ tergum / notum ▪ Mesothorax have one pair of leg ✓ sternum ▪ Metathorax ✓ pleuron Pterothorax – fused mesothorax and metathorax  z The THORAX PROTHORAX MESOTHORAX PROTHORAX ▪ 1st segment ▪ Middle segment ▪ Last thoracic segment that comes after the ▪ Bears the first pair of leg ▪ Bears a pair of legs and first mesothorax (prothoracic legs) pair of wings or the Forewings ▪ Bears pair of legs and ▪ Can modify into shield-like the second pair of structure such as in wings (Hindwings) cockroaches (Pronotum) ▪ Can be large plate such as in Orthoptera, Hemiptera and Coleoptera z Structures of Insect Thorax SPIRACLE TYMPANUM Breathing organ Hearing organ Appendages of Insect Thorax z LEGS ▪ coxa ▪ trochanter ▪ femur ▪ tibia ▪ tarsus ✓ Tarsomere ( max number : 5) ▪ pretarsus  Appendages of Insect Thorax z LEGS ▪ Coxa – 1st segment, short and stout, it articulates with the thorax ▪ Trochanter – 2nd segment, small and freely movable in vertical direction in coxa ▪ Femur – largest and strongest segment; equipped with spines and other cuticular modifications especially in predatory insect ▪ Tibia – long and slender, can be flexed against femur for more locomotory power (grasshoppers); often bears spines for grooming or for engaging the substrate to aid locomotion ▪ Tarsus – divided into 5 or fewer segments which is referred to as tarsomeres ▪ Pretarsus – these are claw-like segments which allows the insect to climb and hold onto smooth surfaces  Types of Insect Legs z AMBULATORY / GRESSORIAL CURSORIAL SALTATORIAL Walking legs Running legs Jumping legs Fairly normal segments and Coxa well-developed Femur enlarged and tibia elongated slender Example : cockroach Example : Hindlegs of grasshopper Examples : housefly, leaf beetles  Types of Insect Legs z FOSSORIAL RAPTORIAL Digging or burrowing legs NATATORIAL Grasping legs Coxa and femur very broad, flat and Swimming legs Coxa long, femur enlarged dense Femur and tibia flattened and broad Femur and tibia with two rows Tibia with spade-like tines Tarsi fringed with dense hairs and of sturdy spines Tarsal claws unusually big and strong serves as oar Example : Foreleg of preying Example : foreleg of mole cricket Examples : aquatic beetles and bugs mantis  z Types of Insect Legs SCANSORIAL Clinging legs Tarsus modified to have thumb in addition CORBICULATE to sharp claw Foraging or pollen-gathering legs Example : head louse Legs with depressed area (pollen basket) and fringed with hair Exmaple : hindleg of female (worker) bee z Appendages of Insect Thorax WINGS ✓ Organ of flight; also for protection and balancing of flight ▪ Veins ✓ C : Costa ✓ Sc : Subcosta ✓ R : Radius ✓ Cu : Cubitus ✓ A : Anal ✓ J : Jugal  Types of Insect Wings z Types Description e. g. Elytra Hard sclerotized front BEETLES – wings serving as protective Coleoptera cover for membranous hindwings Hemelytra Front wings that are TRUE BUGS - leathery or parchment –like Hemiptera at the base and membranous at tip Tegmina Front wings that are GRASSHOPPERS; completely leathery or MANTIDS- parchment-like in texture Orthoptera  Types of Insect Wings z Types Description e. g. Haltere Small, knob-like FLIES – Diptera structure serving as gyroscopic structure Fringed Wings Margins of slender THRIPS - front and Thysanoptera hindwings with long fringes of hair  Types of Insect Wings z Types Description e. g. Membranous Soft, flexible, BEES, wings translucent or DRAGONFLIES, transparent with DAMSELFLIES- prominent wing veins Hymenoptera; Odonata Membranous Wings covered with BUTTERFLIES with scales powder-like substance MOTHS – Lepidoptera  z Types of Insect Wings MEMBRANOUS SCALY ELYTRA Soft, flexible, translucent or Wings covered with scales Chitinous / hardened wings transparent Example : butterflies Example : forewings of beetles Wing veins prominent Examples : honeybees, dragonflies  z Types of Insect Wings HEMELYTRA Basal half of wings thickened and TEGMINA apical membranous Leathery wings FRINGE HALTERES Example : forewing of bugs Examples : cockroach, With extending hairs on Small, knob-like grasshopper margin structures Example : thrips Example : hindwing of flies z INSECT ABDOMEN z The ABDOMEN ▪ simple ▪ anterior segments without any appendages ▪ segments usually 10-11 ▪ Terga- dorsal abdominal segments ▪ Sterna –Ventral segments ▪ capable of expansion for food storage and production of egg z Structures of Insect Abdomen SPIRACLES TYMPANUM the small external opening of a hearing organ trachea (respiratory tube) in insects z Appendages of Insect Abdomen CERCI CORNICLES Sensory organs; STYLI Found in aphids Used to subdue prey; use to Used to hold females Secretes alarm pheromones propel themselves through during copulation water; role in copulation  z Appendages of Insect Abdomen AEDEAGUS Penis of insects Male copulatory organ OVIPOSITOR Egg laying apparatus of female insects, needle or blade-like such as in crickets and Katydids BURSA COPULATRIX reproductive organ of females CLASPERS Used to hold mate during copulation