Devo Lect 21 - Insect Meta.

Question 2

Ametabolous

Answer 2

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

Question 3

Hemimetabolous

Answer 3

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

Question 4

Holometabolous

Answer 4

Very significant changes from larva to adult

Question 5

Ecdysis and function

Answer 5

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

Question 6

Instar

Answer 6

One larval stage. Holometabolous organisms have several instars before metamorphosis

Question 7

Metamorphic molt

Answer 7

Last molt before larva becomes pupa

Question 8

Imaginal molt

Answer 8

Molt from pupa to adult (butterfly)

Question 9

How many stages does Drosophila have?

Answer 9

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

Question 10

Ecdysone description

Answer 10

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

Question 11

Ecdysone production

Answer 11

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

Question 12

Polytene chromosomes and ecdysone

Answer 12

Puffs show where ecdysone turns genes on

Question 13

Process of molting

Answer 13

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

Question 14

Apolysis

Answer 14

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

Question 15

Expansion

Answer 15

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

Question 16

Eclusion

Answer 16

Another word for imaginal molt

Question 17

Instars

Answer 17

Period in between losing an exoskeleton

Question 18

Imaginal disks

Answer 18

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

Question 19

Cause of metamorphosis experiment

Answer 19

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

Question 20

Corpus allatum

Answer 20

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

Question 21

JH

Answer 21

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

Question 22

JH signaling loop

Answer 22

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

Question 23

Kr-h1

Answer 23

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

Question 24

Mosquitoes

Answer 24

Holometabolous; females suck blood for nutrient

Question 25

Problems with insecticides

Answer 25

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

Question 26

Methoprene

Answer 26

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