Determination of ecdysteroid titers by a double-antibody precipitation in the tropical warehouse moth, Ephestia cautella (Lepidoptera, phycitidae)

1. 1. The level of ecdysteroids in whole-animal extracts of Ephestia cautella was determined in the last larval instar until pupation. 2. 2. The study was done with radioimmunoassays (RIAs) by utilizing two antisera with different affinities for ecdysone and 20-hydroxyecdysone. 3. 3. Two distinct peaks of ecdysteroid activity were recorded: a small peak prior to the onset of the wandering stage which is supposed to direct the cellular reprogramming from larval to pupal character, and a large peak shortly prior to pupation initiates the process and events associated with pupation. 4. 4. A comparison was made between the common RIA procedure using ammonium sulphate for the separation of bound and unbound ecdysone and double-antibody precipitation using a second antibody (goat antirabbit IgG), commonly used in vertebrate hormone RIAs.