Juvenile hormone

Juvenile hormone (JH ) is a hormone of insects, which regulates the formation of the larval characteristics, or the product of molting is specifies. There are different types of JH ( JH0 to JHIII, 4 -methyl- JHI, 12'- OH JHIII, 8'- OH - JHIII, 4' -OH - JHIII ). JHIII comes as Lone in all insect orders before, JHI, II and 0 only in butterflies.

Biological Function

While the hormone ecdysone triggers a periodic molting, will determine if the concentration of juvenile hormone, whether it comes to a Larvalhäutung or pupation in holometabolous insects or adult molt at hemimetabolic insects. In the presence of JH it comes to Larvalhäutungen. If the concentration but below a certain threshold, the result at the next molt a doll. From this finally slips the Imago.

In adult insects JH also stimulates the synthesis of vitellogenin, and its incorporation into the egg.

Excessive doses lead to developmental disturbances in the form of surplus Larvalhäutungen. This often show malformations, in addition, the animals can no longer completely hides and then die before they reach their reproductive adult stage. This effect is exploited many plants by producing juvenoids in order to ward off predators (eg juvabione in the balsam fir or farnesol at lily of the valley ). Following the same principle function of juvenile hormone analogues (eg, fenoxycarb ), which can be used as an insecticide in agriculture. Disadvantage is the lack of species specificity as well as the hydrophobic properties of the juvenile.

If one removes the early juvenile hormone in an insect larva, then this chrysalis, but does not grow up to be their full size.

Biosynthesis

JH is in the behind the brain usually occurring in pairs corpora allata ( singular: corpus allatum ) formed and discharged directly into the hemolymph, where it binds to specific transport proteins. Storing JH does not occur. The synthetic activity of the corpora allata is controlled by inhibitory ( allatostatin ) and activating ( allatotropin ) factors.

Others

Chemically speaking, juvenile sesquiterpenes.