Insect Antifeedant Novel Limonoids from the Roots of Melia azedarach

Department of Chemistry, Dr. H. S. Gour University, Sagar-470 003 Manuscript received 10 May 1994, revised 20 October 1994, accepted 12 January 1995 An extract of the roots of Melia azedarach has yielded four new limonoids, azecins 1, 2, 3 and 4, whose structures have been determined by ir, 1H, 13C nmr, uv and mass spectra. The isolated azecins 1 and 3 are effective antifeedants when incorporated into the fourth instar larva of Spodoptera litura and third instar of grub stages of brinjal bettie Henosepilachna vigitioctopunctata Fabricus. Reduced growth rate and increased time of pupation are evident at lower dose levels while significant mortility is noted at higher dose levels