CRPR

• Exoskeleton


  The skeleton of an insect that is on the outside of its body and serves as a support for muscles and internal organs as well as a covering
• Molting


  1. The process where an insect sheds its rigid exoskeleton and replaces it with a larger one as the insect grows

  2. The life stage between each molt is called an instar

  3. govern by hormones, serves as a support for muscles and internal organs
• Ecdysone


  A steroid hormone that controls cuticle secretion and the molt cycle
• Molting process

  1. Hormone secreted by a gland in the thorax, controlled by a hormone from the brain

  2. When the brain receives the appropriate stimulus, the insect will molt

  3. A new cuticle forms under the old one, then the old exoskeleton splits and the insect wriggles its way out
• Many insects eat their own discarded skin
• The new cuticle is soft at first, the insect may swallow air to expand its own volume and stretch the new exoskeleton before it hardens, usually within about an hour
• Determinate growth


  Insects that have a fixed number of molts
• Indeterminate growth

  Insects that continue to molt indefinitely
• Stages of molting

  2. Apolysis- Molting hormones are released into the hemolymph and the old cuticle separates from the underlying epidermal cells.

  3. Ecdysis- This begins with the splitting of the old cuticle, usually starting in the midline of the thorax’s dorsal side
• Molting hormones are released into the hemolymph and the old cuticle separates from the underlying epidermal cells
• The epidermis increases in size due to mitosis and then the new cuticle is produced
• Enzymes secreted by the epidermal cells digest the old endocuticle, not affecting the old sclerotised exocuticle
• Ecdysis


  1. Begins with the splitting of the old cuticle, usually starting in the midline of the thorax's dorsal side

  2. The rupturing force is mostly from hemolymph pressure that has been forced into thorax by abdominal muscle contractions caused by the insect swallowing air or water

  3. After this the insect wriggles out of the old cuticle
• Sclerotization


  1. After emergence the new cuticle is soft and this a particularly vulnerable time for the insect as its hard protective coating is missing

  2. After an hour or two the exocuticle hardens and darkens

  3. The wings expand by the force of hemolymph into the wing veins
• Ametabolous


  No metamorphosis, the only difference between adult and nymph is size
• Ametabolous insects


  • Order: Thysanura (Silverfish)
• Hemimetabolous


  Incomplete metamorphosis, the terrestrial young are called nymphs and aquatic young are called naiads, wings appear as buds on the nymphs or early instars, when the last moult is completed the wings expand to the full adult size
• Hemimetabolous insects


  • Order: Odonata (Dragonflies)
• Holometabolous


  Complete metamorphosis, the immature form is called larvae and remains similar in form but increases in size, they usually have chewing mouthparts even if the adult form mouth parts suck, at the last larval instar phase the insect forms into a pupa, it doesn't feed and is inactive, and here wing development is initiated, and the adult emerges
• Holometabolous insects


  • Order: Lepidoptera (Butterflies and Moths)
• Sexual reproduction


  The egg is produced by the female, fertilized by the male and oviposited by the female
• Parthenogenesis


  Reproduction without male input, the offspring are essentially identical to the mother, most often seen in aphids and scale insects
• Insect body regions


  • Head
  • Thorax
  • Abdomen
• Head


  • 6 fused segments with compound eyes (ommatidia), simple eye ocelli, antennae and mouthparts which differ according to the insect's particular diet
• Thorax


  • 3 segments (pro, meso and meta thorax), each supporting a pair of legs which may also differ, depending on function, usually the middle and the last segment have paired wings
• Abdomen


  • Generally comprises 11 segments and contains the digestive and reproductive organs
• Insect mouthpart types


  • Grinding
  • Sucking
  • Lapping
  • Chewing
• Insect leg types


  • Jumping
  • Digging
  • Swimming
  • Running
• Insect antennae types


  • aristate
  • lamellate
  • flabellate