Ecdysteroid

Ecdysteroids are arthropodsteroid hormones that are mainly responsible for molting (ecdysis), development and, to a lesser extent, reproduction; examples of ecdysteroids include ecdysone, 20-hydroxyecdysone (ecdysterone), turkesterone and . These compounds are synthesized in arthropods from dietary cholesterol via the Halloween family of cytochrome P450 enzymes.

Compounds with ecdysteroid activity in arthropods are not only produced by these animals (zooecdysteroids). Phytoecdysteroids appear in many plants, mostly as protection agents (toxins or antifeedants) against herbivorous insects. Fungi produce a handful of mycoecdysteroids. In addition, synthetic ecdysteroid pesticides such as have been produced.