Interaction of insect hormones, Biology

Interaction of insect hormones in the process of metamorphosis

The organs and the hormones usually included in metamorphosis of insects. This is since despite the fact that there may be around 1 million dissimilar insect species, there is a striking similarity in the endocrine function of dissimilar hemimetabolous and holometabolous insects. Figure depicts a schematic outline of the interaction of hormones in the metamorphosis of insects. On the basis of figure let us study how the actions of the several hormones bring about metamorphosis in insects. The moulting process, the beginning of metamorphosis, is initiated in the brain. The stimulus may be neural, hormonal or environmental, and causes the neurosecretory cells of the brain to release the activation hormone that after synthesis changes into the active hormone known as prothoracic opic hormone (PTTH). The PTTH stimulates the prothoracic gland to generate ecdysone.

Ecdysone after being transformed into its active form, the ecdysterone, stimulates growth and causes the epidermis to secrete a new cuticle, start the moulting process. The ecdysterone further stimulates the epidermal cells to synthesize enzymes which digest and recycle the components of the cuticle. As long as the juvenile hormone is present, the ecdysone-stimulated moult results in a new larval instar. In the last larval instar stage, the synthesis of juvenile hormone is decreased, causing its levels to drop below a critical threshold value. This again triggers the release of PTTH from the brain. The PTTH in turn, stimulates the prothoracic gland to secrete not usually large quantity of ecdysone. The resultant ecdysterone, in the relative scarcity of JH, causes the instar to pupate. In other word the occurrence of the subsequent moult in the larva in the relative scarcity of JH and abundance of ecdysone, shifts the organism from larva to pupa. Throughout the period of pupation the corpora allata do not release any juvenile hormone and the ecdysterone stimulates the pupa to metamorphoses into the adult insect.

Posted Date: 1/31/2013 12:07:10 AM | Location : United States







Related Discussions:- Interaction of insect hormones, Assignment Help, Ask Question on Interaction of insect hormones, Get Answer, Expert's Help, Interaction of insect hormones Discussions

Write discussion on Interaction of insect hormones
Your posts are moderated
Related Questions
Classification of hydrocolloids by function It must be clear to you now that gum ghatti, gum karaya, gum tragacanth ( classified as exudate gums) locust bean  gum, guar g


At 1:00AM, Neuron A is at rest with membrane potential equal to -70 millivolts; it is producing no action potentials.  The threshold for an action potential in neuron A is -55 mill

Reproductive Organs In several metazoans, gonads are well-defined. Testes and ovaries take up dissimilar shapes and anatomical dispositions. In cases of certain hermaphrodites

Define the Concept of Health - Public Nutrition? The most widely accepted definition of health is the one given by WHO (1948) in the preamble to its constitution, Box 1 gives t

Phylum Sarcomastigophora Locomotory organelles - flagella, pseudopodia or both types, usually with one type of nucleus; typically no spore formation, sexual reproduction thro

Rheumatic fever is an immunologically mediated connective tissue disorder following throat infection with group-A streptococci (GAS). It is characterised by an inflammatory proces

Q. Show the value of embryology? The value of embryology in solving taxonomic problems can be appreciated by studying some specific cases. Amongst the classical examples cited

Differential reinforcement of low response rate (DRL) This is used to encourage low rates of responding. Example: "If you ask me for a potato chip no more than once every 10 mi

Vaccinia-like disease Smallpox caused by variola virus (VARV) has successfully been eradicated in the last quarter of the 20th century. However, vaccinia like viruses (VLVs) , viz.