FWD: Metamorphosis Of Butterflies GEHP

[Joe Kunkel]

> This message is from Whitby Community College (Biology Department) <post at whitbycc.force9.co.uk>,
> a A-level Student from Whitby, North Yorkshire, England.
> 
> We are a group of A-level students researching Metamorphosis of Butterflies and are unable to find 
> suitable material. We would be grateful to receive answers to any of the following questions.
> 
> 1. How do the proteins reform within the chrysalis to transforn a caterpillar via metamorphosis ?
The caterpillar's tissues go through a process of remodeling. Pockets of
cell in the larva, called imaginal discs, evert during the molt to the
chrysalis stage.  The chrysalis stage is a forerunner of the form of the
adult. All the epidermal structures of the adult can be seen in the
chrysalis due to the eversion and growth of the pockets of cells for the
wings, legs, antennae and proboscis. The epidermal cells underlying each
of these structures are responsible for synthesizing and secreting the
cuticles that give the characteristic shapes and forms of these
structures.  See Wigglesworth's Physiology of the Insecta for great
detail.
 
> 2.What enzymes are needed for the above process ?
There are scads of enzymes needed for the molting process, for example:
a. Enzymes to dissolve the old cuticle from the inside out.
b. Enzymes to catalyze the assembly of the new cuticle layers.
c. Enzymes to produce the agents that tan and harden the new cuticle
after molting.


> 3. What energy requrements are needed in this process and where is the energy obtained from ?
Energy is stored for the most part in the fat body as lipid and glycogen
which is called upon during the non-feeding periods of the post-feeding
larva and the chrysalis stage.
 
> 4. What protein requrements are asociated with this process ?
There are several storage proteins (Lipophorin and Hexamerins) found in
the haemolymph and fat body which have been reviewed in the literature:
Telfer and Kunkel (1991) The function and evolution of insect storage
proteins. Ann. Rev. Entomol. 36:205-28.

> 5. Are there any species of butterflies/moths which are exceptions from this process (metamorphosis) or have unusual behaviour ?
I am reluctant to say much on this subject because almost anything is
possible in nature; BUT the metamorphic process is pretty well
entrenched in the Lepidoptera and I would be amazed if there is a
species that is neotenous to the extent that the larval stage
reproduces.  It would not be impossible since the larval stage of
several moths are known to accumulate the yolk proteins necessary for
egg production already in their last larval stage.  It seems set up to
be able to do it but I guess the winged adult is still important for
transporting the eggs in most cases.  However this seemingly important
behavior has also been given up in such species as the gypsy moth in
which the female can not fly and dispersal is by ballooning of the
larva.
I hope this last flight of fancy stimulates some thinking.
Joe
-- 
--------------------------------------------
Joseph G. Kunkel, Professor
Biology Department
University of Massachusetts at Amherst
joe at bio.umass.edu
http://www.bio.umass.edu/biology/kunkel/