Devo Lect 21 - Insect Meta. Flashcards Preview

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Flashcards in Devo Lect 21 - Insect Meta. Deck (25):
2

Ametabolous

Pronymph to adult doesn’t require much change. Not really metamorphosis.

3

Hemimetabolous

Pronymph goes through nymph stages before adult which is significantly different (ie wings)

4

Holometabolous

Very significant changes from larva to adult

5

Ecdysis and function

Ecdysis = molting. Exoskeleton is basically thick ECM limits growth of larva, needs to molt in order to continue growing. Accomplished by increasing movements etc.

6

Instar

One larval stage. Holometabolous organisms have several instars before metamorphosis

7

Metamorphic molt

Last molt before larva becomes pupa

8

Imaginal molt

Molt from pupa to adult (butterfly)

9

How many stages does Drosophila have?

3 larval instars, then pupa then adult for a totally of 4 molts

10

Ecdysone description

Hormone involved in molting; steroid based so it can go through membranes and turn on genes needed

11

Ecdysone production

cyclical; peaks just before a molt, then drops and hits low at molt

12

Polytene chromosomes and ecdysone

Puffs show where ecdysone turns genes on

13

Process of molting

Apolysis, new cuticle produced, old cuticle digested, ecdysis, expansion, darkening and hardening, maturing

14

Apolysis

Glands in epidermis start secreting enzymes that create separation b/w old cuticle and epidermis

15

Expansion

Old cuticle is flexible, needs to be larger so the larva can grow. It will take in water or air to stretch it out

16

Eclusion

Another word for imaginal molt

17

Instars

Period in between losing an exoskeleton

18

Imaginal disks

Epidermal thickenings which will become antenae, limbs etc; these cells are determined; can be studied in vitro (and they produce structures)

19

Cause of metamorphosis experiment

Decapitate first instar larva, connect to head of adult, undergoes metamorphosis

20

Corpus allatum

Piece of insect brain which secretes JH, experiments show that it keeps larva from doing metamorphosis

21

JH

juvenile hormone, from corpus allatum. Prevents metamorphosis, not sure what it targets exactly

22

JH signaling loop

JH from corpus allatum; neurosecretory cells release prothoracicotropic hormone, causes prothoracic gland to release ecdysone, molting occurs. No JH in adult.

23

Kr-h1

Kruppel homolog-1; activated by JH injection; if blocked by RNAi, then metamorphosis happens early

24

Mosquitoes

Holometabolous; females suck blood for nutrient

25

Problems with insecticides

Used to manage insects; problems are killing all insects, or toxicity on other species

26

Methoprene

JH analog, more stable; keep them in pupal state, they will die; specific to insects and only to those that use water in their life cycle, others are ok; pretty expensive, doesn’t last too long