Plumbagin and azadirachtin deplete hemolymph ecdysteroid levels and alter the activity profiles of two lysosomal enzymes in the fat body of Helicoverpa armigera (Lepidoptera : Noctuidae)

The profile of hemolymph ecdysteroid was studied in the gram pod borer, Hel icoverpa armigera, during larval-pupal transformation. The changes closely correspond to the developmental events occurring at metamorphosis. Two inse ct growth regulators, plumbagin and azadirachtin, significantly depleted th e content and altered the profile of ecdysteroids at crucial stages, when a pplied at ED50 doses. The activity profiles of two fat body lysosomal enzym es, acid phosphatase and beta-galactosidase, were also significantly affect ed by the insect growth regulators. It is suggested that plumbagin and azad irachtin treatments primarily modify the ecdysteroid titer, which in turn l eads to changes in lysosomal enzyme activity causing overt morphological ab normalities during the metamorphic molt.