Nigg, H.N., Insect Physiology Laboratory, Beltsville, 20705, Maryland, United States
Svoboda, J.A., Insect Physiology Laboratory, Beltsville, 20705, Maryland, United States
Thompson, M.J., Insect Physiology Laboratory, Beltsville, 20705, Maryland, United States
Kaplanis, J.N., Insect Physiology Laboratory, Beltsville, 20705, Maryland, United States
Dutky, S.R., Insect Physiology Laboratory, Beltsville, 20705, Maryland, United States
Robbins, W.E., Insect Physiology Laboratory, Beltsville, 20705, Maryland, United States

An enzyme system that converts α-ecdysone to its hormonally less active 3α-epimer was detected only in the midgut of the tobacco hornworm, Manduca sexta (L.). This system appears to be specific for the ecdysones and may represent a metabolic control point for regulating molting hormone activity. © 1974 American Oil Chemists' Society.