Anti-juvenile hormone activity of azacoprostane depends on inhibition of molting

✍ Scribed by Louis Safranek

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 138 KB
• Volume: 34
• Category: Article
• ISSN: 0739-4462
• DOI: 10.1002/(sici)1520-6327(1997)34:1<43::aid-arch4>3.0.co;2-x

✦ Synopsis

Administration of the anti-ecdysteroid azasteroid 25-azacoprostane (AZCP) to larvae of the tobacco hornworm, Manduca sexta, often inhibits molting without curtailing growth. As a result, AZCP-treated larvae may attain weights 2-3 times greater than normal during the first four instars. This may explain the paradoxical anti-juvenoid activity of AZCP evident in the precocious metamorphosis of AZCP-treated fourth-instar larvae, which was noted only after those larvae attained unusually large weights over 2 g. The weight interval of 2-3 g has been previously identified as a critical threshold for initiation of metamorphosis by normal final (fifth) instar larvae. The premature attainment of this weight threshold by AZCP-treated fourth-instar larvae probably activates the same premetamorphic sequence of events that normally occurs in the fifth instar at this threshold, including activation of potent endogenous anti-juvenoids. Anti-juvenoid activity limited to the penultimate instar is likely to be a general feature of compounds that block molting without inhibiting growth.