EFFECTS OF ECDYSTEROID AGONIST RH-5849 ON PUPAL DIAPAUSE OF THE TOBACCO HORNWORM (MANDUCA-SEXTA)

The tobacco hornworm (Manduca sexta) exhibits facultative pupal diapau se which is induced by the exposure of young larval instars to short d ay lengths. The daily body weight of pupae kept in constant humidity a nd the absence of eye pigmentation, were used as good markers for diap ause in this species. The nonsteroidal ecdysone agonist, RH-5849, has proven to be very effective in inducing adult development in diapausin g pupae in a dose-dependent manner. It was found that injection of 0.5 mu g/g of pupal weight of acetone solution of this compound resulted in immediate cessation of the diapause and led to normal adult develop ment and emergence. Higher doses (1-2 mu g/g of body weight) caused em ergence of the adults having deformed wings. Doses exceeding 2.5 mu g/ g of pupal weight caused hyperecdysonism, resulting in abnormal premat ure development without emerging from pupae. RH-5849 dissolved in acet one is about 13 times more effective in breaking the diapause as compa red with the ethanol solution. (C) 1997 Wiley-Liss, Inc.