The tetranortriterpenoid class of chemical compounds most noted for the chemical azadirachtin, extracted from the neem tree (Azadirachta indica) that displays insecticidal properties. Azadirachtin mimics insect hormones called ecdysones that regulate pupation of insects; application of azadirachtin interrupts the development and pupation of insects, which eventually kills them.
Azadirachtin is a limonoid.
References
Tetranortriterpenoid Wikipedia(Text) CC BY-SA