Insect Molting Metamorph Flashcards
In what ways does the neuroendocrine system influence insect biology?
-Molting and metamorphosis, homeostasis, migration, mating, oviposition… To name only a few.
What are the key chemicals that allow insects to make adaptations and grow?
Hormones, transported by hemolymph to target tissues and produced in endocrine glands. hormones used in conjunction with brain to regulate specific behaviours.
What are the endocrine glands?
Pro thoracic gland: located in thorax or back of head. Produces ecdysone (Molting hormone) Targets epidermal cells to produce new cuticle.
Corpus allata: pair of glands to either side of foregut. Produce juvenile hormone, regulating metamorphosis and female reproduction.
Corpora cardiaca - a pair of glands behind brain. Produces PTTH (prothoracicotropic hormone) An important neurohormone in metamorphosis.
What cells produce hormones?
Neurosecrectory cells in brain - Master Regulators
What is ecdysis?
Molting - triggered by the release of ecdysone from prothoracic glands and allows insects to build onto cuticle to form adult bodies.
What is the most crucial organ to insect success?
Cuticle.
- Complex organ of diverse structure and; function – key to insect success
- ‘Engineering marvel’ with unique properties – remarkable adaptability:
- Rigidity and great strength (protection and muscle support for locomotion)
- Impermiability – structure prevents evaporative water loss; also prevents entry of pathogens
- Cuticle pigments and body colouration. (Offers unbelievable camouflage and defensive colouration.)
What is the disadvantage of the cuticle?
Exoskeletons are limited in body size and must be periodically shed in order for molting to occur. (Ecdysis)
What are some functions of insect color patterns?
-sexual displays, camo, mimicry. All are a result of cuticle adaptation.
Explain cuticle structure.
- Complex, multi-layered structure
- Tremendous versatility related to kinds of molecules (chitin a sell as various proteins) comprising cuticle
- Non-living cuticle (comprised of thick procuticle overlain by thin outer epicuticle)
- Epidermis (living monolayer of cells) functions to produce the cuticle
- Basement membrane separates cuticle from hemocoel
- Varies in structure and function with space and time
- Cuticle structure precisely regulated according to function and timing of insect’s life cycle
What is commonly combined to build specific cuticle types?
Various proteins are combined with cuticle to produce pro cuticle and epicuticle
How does structure and function of cuticle vary over time?
- Very dynamic system
- Varies with space on the insect body. Different functions for different areas.
- Varies with time as it changes to accommodate the insect for specific parts of its life. Triggered by ecdysone.
Describe molting in insects
Must periodically shed cuticle (ecdysis or molting) for growth to occur - Stage between molts = instars (usually five)
- Remarkably complex process regulated by neuroendocrine system (hormone = ecdysone)
- Leads to shedding of old cuticle and formation of new one
When does all growth in most insects occur?
As a larva. Usually 5 larval stages (Instars) where larva molt.
How is molting initiated and fulfilled?
Ecdysone from prothoracic gland travels through hemolymph to stimulate the epithelial cells to produce chitin. The chitin is combined with various proteins, synthesized in the midgut and traveling through hemolymph to create the various types of cuticle required.
When does molting generally occur?
At night in order to avoid added daytime predation.
