EFFECTS OF WET ENVIRONMENT ON ECDYSONE 20-MONO-OXYGENASE AND ECDYSTEROID LEVELS DURING WANDERING BEHAVIOR OF NEOBELLIERIA-BULLATA AND PARASARCOPHAGA-ARGYROSTOMA LARVAE

The wet environment (Ohtaki-type wet synchronization) causes low ecdys teroid level in Neobellieria bullata wandering-stage larvae. In Pavasu rcophaga argyrostoma and N. bullata larvae, the lower than normal ecdy steroid level does not cause feedback inhibition of the ecdysone 20-mo no-oxygenase activity which consequently can reach a significantly hig her value. the pupariation time is appreciably reduced when larvae are exposed to a 70 mu M methoprene (a juvenoid)-containing water treatme nt following a previous dry period of 0, 1, 3 or 6 hr, and to 70 mu M 20-hydroxyecdysone-containing water after a previous dry period of 0, 3 or 6 hr. Independently of the length of the dry period, 20-hydroxyec dysone induces retraction of the anterior segments and causes scleroti zation of the anterior part. RH 5849, a receptor-level ecdysteroid ago nist, has no detectable effect on the pupariation process of N. bullat a.