In the present study, the essential oil from Cinnamomum verum (Lauraceae) and Cuminum cyminum (Apiaceae) was isolated and its insecticidal activities were determined against Tribolium castaneum. Essential oils were isolated by hydrodistillation method using Clevenger apparatus. Experiment was carried out at 27 ± 2 ˚C and 60 ± 5% R. H. under dark condition adopting a complete randomized block design. For each essential oil, four concentrations with six replications were tested. These essential oils caused death of first instar larvae and adults of T. castaneum when fumigated. The maximum concentration of essential oils (0.56 µl/cm3 ) of C. cyminum and C. verum caused, 100% and 96.2% mortality of first instar larvae and 95% and 91% mortality of adults, respectively. LC50 values were calculated using probit MsChart software by recording the mortality at 24 h. The LC(50) values against the adults of the insect were 0.044 and 0.040 µl/cm3 and against first instar larvae were 0.058 and 0.045 µl/cm3 for C. verum and C. cyminum oils respectively. All the responses were found concentration-dependent. The toxic and developmental inhibitory effects may be due to suffocation and inhibition of various biosynthetic processes of the insects at different developmental stages [1,2].
