Metamorphosis in insects

meta morphosis in insects and hormonal control of metamorphosis

1. By IQRA ASLAM 12051514-074 Metamorphosis in Insects

2. Metamorphosis in Insects The transformation of an immature insect from a larva to a pupa to an adult

3. Types of metamorphosis Ametabolous metamorphosis Gradual metamorphosis Incomplete metamorphosis Complete metamorphosis

4. Ametabolous metamorphosis ( Ametamorphosis )"without metamorphosis eggs …………….. immatures same shape as the adults . get bigger no distinct rearrangements of body structures .

5. Immatures ……….juveniles. Changes in form during growth are minor all immature stages resemble adults.

6. Examples Springtails silverfish firebrats

7. Gradual metamorphosis Immatures are called nymphs . Change in form is gradual , obvious changes involving development of external wing pads differences in color or markings. Nymphs and adults generally share the same habitat . grasshoppers ,crickets and true bugs

8. Complete metamorphosis ( Holometabolous )   Immatures are called larvae and pupae . Butterflies, moths , beetles , flies , ants , bees and wasps. Larvae do not resemble adults. Wings and other adult features ………..an immobile pupal stage. Immatures and adults may or may not share habitats. Immatures are adapted for feeding adults are adapted for reproduction and dispersal . Instar : The insect itself between molts ... "third instar (larva)"

9. Incomplete metamorphosis ( Hemimetabolous ) Immatures are called naiads . Mayflies ,dragonflies , damselflies and stoneflies. Immatures do not closely resemble adults naiads have tracheal gills. transition to adult form is gradual Nymphs and adults dwell in different habitats.

10. Hormonal control of metamorphosis In immature insects Corpora allata …………. juvnile hormone   inhibits the genes ,promote development of adult causing the insect to remain "immature" The corpora allata shrink during the last larval or nymphal instar stop producing juvenile hormone.   and causes the insect to molt into an adult ( hemimetabolous ) or a pupa ( holometabolous ).

11. approach of sexual maturity brain neurosecretory cells brain hormone " reactivates" the  corpora allata  juvenile hormone.    

12. In adult females………… stimulates production of yolk for the eggs. In adult males………….stimulates the accessory glands to produce proteins needed for seminal fluid and the case of the spermatophore .   In the absence of normal juvenile hormone production, the adult remains sexually sterile.

13. Hormonal Control of Insect Metamorphosis Brain Temperature, Light, Stress, etc. Corpus Allatum Juvenile Hormone (JH) Larva Pupa Adult

14. Thank you for your attention