ENDOCRINE BACKGROUND OF HOW 20-HYDROXYECDYSONE AGONIST, RH-5849, INFLUENCES DIURNAL PATTERN OF PUPATION IN SPODOPTERA-LITTORALIS

Under laboratory conditions (L16:D8, 24 degrees C, r.h. 80%), applying of an ecdysone agonist, RH 5849, (1,2-dibenzoyl-1-tert-butylhydrazine ) onto final instar larvae of Spodoptera littoralis (Boisd.), Noctuida e, Lepidoptera, delayed or advanced the time of pupation depending on the time of treatment. This response was dose-dependent. In addition, non-lethal doses of RH 5849, ranging from 0.05 to 10 mu g/larva were u sed. Following treatment of S. littoralis larvae with 5 mu g RH 5849 t he endogenous ecdysteroid level was increased or decreased depending o n the time of application. Based on the results presented, we suggest that potential users of non-steroidal ecdysone agonists should conside r the proper circadian timing of application in the field.