A crude acetone extract and oil of ripe fruits from Melia azedarach L. were evaluated
against the 2nd and 4th instar larvae of Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae). Both oil and extract exhibited highly significant growth inhibition at all concentrations
tested, while the oil of M. azedarach recorded higher insecticidal activity against both instars
than the crude extract. GC-MS analysis of the oil revealed the presence of linoleic acid
methyl ester, oleic acid methyl ester, and free oleic acid as the main components in addition
to hexadecanol, palmitic acid, methyl esters of stearic acid and myristic acid. Fatty acids
and their esters were not only the main constituents of essential oil from the ripe fruits of
M. azedarach, but also mainly responsible for the insecticidal and growth inhibition activity
against S. littoralis.