Chitin synthesis in Spodoptera frugiperda wing imaginal discs: I. Chlorfluazuron, diflubenzuron, and teflubenzuron inhibit incorporation but not uptake of [14C]N‐acetyl‐D‐glucosamine

Abstract

AbstractThe purpose of this study was to determine the effects of potent inhibitors of chitin synthesis on an organ culture test system as a basis for determining the mode of action of such compounds. Consequently, we investigated the action of chlorfluazuron (CFA), diflubenzuron (DFB), and teflubenzuron (TFB) on uptake and incorporation into chitin of [14C]N‐acetyl‐D‐glucosamine ([14C]GlcNAc) in wing imaginal discs cultured in vitro. Spodoptera frugiperda wing imaginal discs provided a highly responsive test system for studying the inhibition of ecdysteroid‐dependent chitin synthesis in a target tissue in vitro.All three inhibitors blocked ecdysteroid‐dependent [14C]GlcNAc incorporation into chitin by the wing imaginal discs. The effectiveness of the inhibitors was not affected by the time of their application, i.e., exposures before, during, or after 20‐hydroxyecdysone treatment were equally effective in inhibiting chitin synthesis. Thus, exposure of freshly dissected discs to CFA for periods as short as 15 min inhibited approximately 90% of the chitin synthesis measured 72 h later. In contrast to previous in vivo studies all three inhibitors were similar in their effectiveness in vitro. However, while all three compounds inhibited [14C]GlcNAc incorporation in a similar dose‐dependent manner, only DFB and TFB reduced but did not block uptake of GlcNAc. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.