Solvent extracts of dlfferent parts of the neem tree (Azadlrachta lndica A. 3uss)
were bioassayed for thelr antlfeedant properties agalnst flrst- and thlrd-instar
larvae of Mythimna reparata. Fraction 'C', obtalned from an ethanollc extract of
the shade-drled neem seeds (Hyderabad, India) was the most effective phagodeterrent
under glasshouse, laboratory and, to a 11mlted extent, fleld conditions.
Fractlon 'C' was further purlfled to fractlon 'M', whlch was subjected to column
chromatography (silica gel) result~ng In IG fractions, AI-l to AI-14. Fractions
AI-9, AI-10 and AI-11 were found to be b~olog~calalyc tive, reduclng leaf feedlng
and larval weight consrderably. None of the treated larvae whlch fed on leaf
dlscs treated wlth the fractions and extracts 'C' and 'M' could pupate. The retentlon
tlme of the malor component of AI-10 on a p BONDAPAK C18 10 u, 3.9
mm ID, 30 cm column (hlgh performance liquid chromatography) was close to
that of azadlrachtln. Spectral lnvestlgatlons revealed that this major component
of A1 1s dlfferent from the antifeedants reported earher from A, indica and Melia
azedarach. It has been des~gnated as vepaol (the Telugu name for neem IS vepa),
and some aspects of 11s structure are discussed. Studles relatlng to the effectiveness
of fraction 'G' on the oriental rmyworm, Mythrmna reparata, and other sorghum pests are presented
