INSECT HORMONES

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INSECT HORMONES
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Manduca sexta
Rhodnius prolixus
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Main Endocrine Centres
Neurosecretory cells in brain
Brain
Neurosecretory cells in SEG
Prothoracic (ecdysial) gland
Corpus cardiacum
Corpus allatum
Neurosecretory cells in VNC
Ovary
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Activity of various neuropeptides
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(No Transcript)
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CH3
CH3
CH3
CH3
CH3
O
CH3
CH2
CH2
C
CH2
O
H
C
CH2
C
C
H
C
CH3
O
H
Ecdysone
CH3
CH3
Juvenile hormone I
CH3
CH3
O
CH3
CH2
CH2
C
CH2
O
H
C
CH2
C
C
H
C
CH3
O
H
CH3
Juvenile hormone II
CH3
CH3
O
CH3
CH2
CH2
C
CH2
O
H
C
CH2
C
C
H
C
CH3
O
H
Juvenile hormone III
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Brain (neurosecretory cells)
Action pathway for JH and Ecdysone
Production, storage and release of PTTH
Corpus cardiacum
Corpus allatum
PTTH stimulates
Low concentration of JH causes pupation
Prothoracic gland
ec
Low concentration of JH causes moulting
Ecdysone (ec)
ec
Larva
Low ºC stimulates PPTH
Pupa
Eggs
JH
-JH
ec
Adult
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Sensitive periods for JH
JH level
Ecdysone level
4th instar
5th instar
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Moulting and Hormones
Outer epicuticle
Epicuticle
Inner epicuticle
Exocuticle
Procuticle
Endocuticle
Epidermis
Basement membrane
Pore canals
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Insect Moulting
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epi-
exo-
endo-
epithelial cells
moulting fluid
subcuticular space
epi-
OLD
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exo-
Ecdysial membrane
New epicuticle-
Undifferentiated procuticle
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Cuticlin layer
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Epithelial cells
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Hormonal Control on Moulting
Gut distended by meal stretch receptors
stimulated
Stimulation of neurosecretory cells in brain
In Rhodnius
PTTH secreted to corpora cardiaca corpora allata
Stimulation of prothoracic gland
Prothoracic gland produces ecdysone
Stimulates corpora allata to produce juvenile
hormone
Ecdysone stimulates activity in epidermal cells
Level of JH determines type of metamorphosis
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Moulting video http//www.vanderbilt.edu/explorat
ion/news/news_bursicon.htm