Insects - hormones in growth and reproduction, Biology

Assignment Help:

Insects - Hormones in Growth and Reproduction

In insects hormones regulate moulting and metamorphosis. The larvae or nymphs which hatch out of the eggs undergo regular moulting that is followed by growth, as in crustaceans and ultimately they become adults. The change in form from larva to adult is termed as metamorphosis. In insects such as cockroach, grasshopper etc., (hemimetabolous insects), the change in form is gradual. Though in some other insects like moths, butterflies, houseflies etc., (holometabolous insects), the change is much more conspicuous during the later period of the life history and the adult that emerges from the pupa is quite different. As in crustaceans, the hormone which brings about moulting in these animals is as well ecdysone but in insects it is secreted through prothoracic glands. How is metamorphosis in insects brought about? In insects the hormone that is accountable for preventing the animal from metamorphosing is juvenile hormone secreted by the corpus allatum. Actually, as the name implies, juvenile hormone keeps the insect juvenile. Thus in effect it inhibits metamorphosis. We have previously seen that the prothoracic glands in immature insects secrete ecdysone. This hormone causes the insect to moult. As long as the larva moults in the existence of high titres of juvenile hormone, it moults into another larva. If the moult occurs when the titres of JH are low in the blood, it results in a pupa. Finally when there is no JH circulating in the blood, the pupa moults into adult. So the concentration of JH in blood determines the type of resulting individual. It is as well known that JH causes the repression of those genes that are accountable for adult differentiation.


Related Discussions:- Insects - hormones in growth and reproduction

Evolutionary advantage of the occurrence of sperm cells, What is the evolut...

What is the evolutionary advantage of the occurrence of sperm cells and larval stage in the life cycle of sponges? The sexual reproduction in sponges, in addition to contributi

Gametogenesis, The process of meiosis in animals is called gametogenesis .I...

The process of meiosis in animals is called gametogenesis .It takes place in the testis in male and ovary in female. Gametogenesis is divided into spermatogenesis (formation of

Calculating the amounts of dissimilar nucleotides, Erwin Chargaff conducted...

Erwin Chargaff conducted a series of experiments in which he was calculating the amounts of dissimilar nucleotides that were present in dissimilar tissues and organisms. These stud

Tissue culture, Note on production of haploid by tissue culture.

Note on production of haploid by tissue culture.

What volume of 19 m formic acid need in experiment, You are interested in u...

You are interested in using formic acid (pKa = 3.75) as a buffer for your biochemical Experiment. a) Would it be most useful for creating a buffered solution at pH 2, 4 or 6? Ex

Different sources of infection, Different sources of infection: There a...

Different sources of infection: There are many sources of infection such as reservoirs, carrier organisms and lifeless objects. Reservoirs : A habitat where the disease cau

How can the presence, Q. How can the presence, function of muscular tissue ...

Q. How can the presence, function of muscular tissue and localization in beings of the phylum Annelida is explained? In these beings there are a longitudinal muscular layer und

Which of mendel''s postulates demonstrated in crosses, Which of Mendel's po...

Which of Mendel's postulates can only be demonstrated in crosses involving at least two pairs of traits? a) Segregation b) dominance/recessiveness c) independent assortment d) unit

Define the general mortality and morbidity risk, Define the General Mortali...

Define the General Mortality and Morbidity Risk? Obesity increases the risk of morbidity and mortality. The obese are more prone to developing morbidities or other chronic dise

What is the function of the plant cell wall, Q. What is the function of the...

Q. What is the function of the plant cell wall? The plant cell wall has protective and structural functions. It plays an significant role in the constraint of the cell size, pr

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd