EFFECTS OF THE NONSTEROIDAL ECDYSTEROID MIMIC TEBUFENOZIDE ON THE TOMATO-LOOPER CHRYSODEIXIS-CHALCITES (LEPIDOPTERA, NOCTUIDAE) - AN ULTRASTRUCTURAL ANALYSIS

Oral treatment indicated that the substituted dibenzoylhydrazine tebuf enozide is a potent nonsteroidal agonist of ecdysteroids when tested o n last instar larvae of the tomato looper Chrysodeixis chalcites. Trea ted larvae showed characteristic signs of precocious moulting within 1 2 h of treatment, leading to head capsule apolysis and cessation of fe eding. Electron microscopic analysis of treated integument revealed a forced, untimely synthesis of a new (epi)cuticle via epidermal cell ac tivation; however, normal procuticle secretion was interrupted since t he large number of procuticular lamellae that normally appear in contr ols was conspicuously absent. Further, phenotypic changes of endocrine gland ultrastructure and that of the foregut epithelium and muscle or ganization were also observed. This compound appears to be a useful to ol in endocrine research and in the control of lepidopteran pests. (C) 1997 Wiley-Liss, Inc.