ENT 220 Midterm

How many segments are in the head?

6

How many segments are in the thorax?

3

Plates in thorax

Notum (dorsal), Pleuron (lateral), Sternum (ventral)

How many segments are in the abdomen?

11

Dorsal, lateral ventral plates in the abdomen

Tergum (dorsal), Pleural membrane (lateral), Sternum (ventral)

Functions of the integument/exoskeleton

• Resistancetodryingout

• Metamorphosis

• Sensory and neuro-motor sophistication

• Mobile winged adults

Layers in the Cuticle

• EPIcuticle

• PROcuticle

  • EXOcuticle

  • ENDOcuticle

Layers in the integument

Cuticle and epidermis

5 layers in the epicuticle

Lacks chitin

• cement layer

• wax layer

• superficial layer

• Outer epicuticle

• Inner epicuticle

What is chitin made of?

Rotating bundles of N-acetyl-D-glucosamine polymers

Sclerotization

Hydrogen bonding of chitin chains, Quinones (phenolic bridges) link proteins, Dehydration of protein chains

Arthrodial membrane

Unsclerotized cuticle, in between joints, caterpillar skin

Cuticle benefits

• water movement

• protection

• barrier to pathogens and predators

• crypsis

• waste products (pigment, chemicals)

• attaching muscles, provides leverage

Cuticle disadvantages

• specific modifications for gas exchange

• specific modifications for sensory reception

• restriction on growth

• molting- vulnerable physically, chemically, osmotically

• Energetic cost of new exoskeleton that must be larger than the old one

5 Main sclerites in the head

vertex, gena, frons, clypeus, labrum

5 main mouthparts

Labrum, Mandibles (2), Maxillae (2) Hypopharynx, Labium

Prognathous

Forward jaw

Opisthognathous

Behind jaw

Hypognathous

Under jaw

Maxillary and labial palps function

chemosensory

Parts that make up the preoral cavity

Chemosensory

Suctorial Mouthparts

nectar feeding in Lepidoptera through proboscis

Piercing-sucking mouthparts

Wide variety of distantly related insects consume liquid food: herbivores (cicada), parasites (mosquitoes), adult fleas, carnivores (assassin bugs), elongated and toothed stylets enclosed by sheath (labium)

Sponging/lapping mouthparts

modifiedmouthpartsof “higher” flies (“suborder” Brachycera)

Chewing-lapping mouthparts

occur in adult bees; mouthparts modified to consume nectar and honey

Galea

elongated maxillae held together by spines and hooks, part of the proboscis, extended by increase in hemolymph pressure, coiled due to elasticity of cuticle and contraction of muscles, nectar sucked up by Cibarium

Hemiptera piercing and sucking mouthparts adaptations

• Mandibles are long stylets

• Maxillae form long interlocking stylets that form anterior food canal and posterior salivary canal

• Efficient muscular pumps in head

• All palpi lost and labrum reduced

• Labium forms long, protective sheath

Mosquito special piercing and sucking mouthparts

Labium -Labellar lobes (modified palpi) for mopping up blood

Mosquito piercing and sucking mouthparts - 6 stylets

• Scissor-like mandibles (2)

• Drill-like maxillae (laciniae-mesial lobe of maxillary stipes) (2)

• Labrum-epipharynx long, sharp— forms food canal (1)

• Hypopharynx long, sharp— contains salivary canal (1)

Tsetse fly (Glossinidae) piercing and sucking mouthparts

• Mandibles and maxillae lost

• Labrum, hypopharynx, labium and maxillary palpi present and similar to mosquitoes

• Labium with protrusible, spiny tip (piercing)

Stablefly (Muscidae) special piercing and sucking mouthparts

Rasping labellar lobes

House fly sponging mouthparts

labellar lobes with pseudotracheae modified for sponging up liquid food

Pseudotracheae

Open tubes that funnel food to the food canal in labrum

Horse flies piercing & sponging mouthparts

Mandibles, maxillae, hypopharynx swords, Labium with pseudotracheae, food canal formed by labrum-epipharynx & hypopharynx

Honeybees and bumblebees chewing-lapping mouthparts

• “Tongue”: glossae (labium)

• Surrounded by tube formed by galea (maxillae) and labial palp

• Sucking pump and tongue draw up nectar

• Mandibles not directly used in feeding

Maggot rasping mouthparts

Highly reduced, mouth hooks used for rasping, Myiasis, predation, decomposing

Odonata (dragonflies, damselflies) Seizing-Grasping mouthparts

Labium elongate, grasping and prehensile hooks, Thoracic / abdominal muscle contraction = hemolymph pressure

Neuroptera & diving beetle larvae Mandibulosuctorial mouthparts

Mandibles & maxillae form scythe-like feeding tubes, contain salivary (poison) canal

Aquatic filtering adaptations in Diptera (Fly) larvae

Labrum with brushes: feeding currents in mosquitoes

Antennae: grasping food

1st body segment name

PROthorax and FOREleg

2nd body segment name

MESOthorax, MIDleg, FOREwings

3rd body segment name

METAthorax, HINDleg, HINDwings

Thoracic sclerites

Notum (dorsal); Pleuron (lateral); Sternum (ventral)

PTEROthorax

Consists of the MESO and METAthorax

Pleuron sclerite sections

episternum (anterior) and epimeron (posterior) by pleural suture (ridge)