Ecdysteroid

The ecdysteroid group includes more than 250 polyhydroxysterols that occur in plants and animals, with 20-hydroxyecdysone (20-OH-E) being the physiologically active moulting hormone in most insects (Lafont 2000).

In some dipteran species, ecdysteroids synthesis starts at almost the same time as the onset of vitellogenin synthesis, whereas in other species like orthopterans the synthesis starts only towards the end of vitellogenin uptake.

Ecdysteroids in crustaceans differ substantially from those of their fellow arthropods, the insects. Crustacean ecdysteroids and ecdysteroid nuclear receptors are similar to those of insects, but differ in the number of hormones and in the number and structure of the receptor isoforms.