Chahal, K.K.Singla, Nancy2018-02-012018-02-012017http://krishikosh.egranth.ac.in/handle/1/5810040217The present investigation deals with Chemistry and insecticidal potential of ajwain seed (Trachyspermum ammi L.) essential oil against rice weevil (Sitophilus oryzae). The ajwain seed essential oil was extracted by hydro-distillation using Clevenger apparatus. Gas chromatography-Mass spectrometry (GC-MS) led to the identification of forty seven compounds with thymol as the major component. Ajwain seed essential oil was subjected to column chromatography to have non-polar and polar fractions and thymol was isolated using dichloromethane as the eluent. Thymol was subjected to reaction with acetic anhydride, n-bromopropane and NH4NO3/KHSO4 which resulted in formation of thymyl acetate, thymyl propyl ether and o- Nitro thymol. Thymol on reaction with diazonium salt undergoes coupling reaction resulting in formation of azo compounds. Thymol and its derivatives were characterised on the basis of melting point, TLC, FT-IR, 1H NMR, 13C NMR spectroscopy. Ajwain seed essential oil, its fractions, thymol and its derivatives were tested for their bioefficacy against adults of Sitophilus oryzae at the concentrations of 1.0, 2.0, 3.0 and 4.0 mg g-1. The observations of mortality were noted after every 24 hours till complete or constant mortality was obtained. The corrected per cent mortality was calculated using Abbott’s formula. The repellent assay was also carried out at same concentrations which showed that all the compounds tested showed attractancy at lower concentration and repellency at higher concentration. The ajwain essential oil was not very effective as antifeedant at 2.0 mg g-1 concentration. Thymol was found to be most potent as a stored grain protectant.ennullThesis