Comparative study on deterrency of Carum copticum C. B. Clarke and Vitex pseudo-negundo (Hausskn.) Hand.-Mzt. essential oils on feeding behavior of Tribolium castaneum (Herbst)

The essential oils extracted from Carum copticum C. B. Clarke and Vitex pseudo-negundo (Hausskn.) Hand.-Mzt. using hydro distillation was tested against the stored product insect, Tribolium castaneum (Herbst), for antifeedant activity. Several experiments were designed to measure the nutritional indices such as relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion of ingested food (ECI) and feeding deterrence index (FDI). Treatments were evaluated by the method of flour disc bioassay in the dark, at 271C and 605 % R. H. Aliquots of 10 µl of acetone (controls) or an acetone solutions of essential oils (100-1500 ppm) were spread evenly on the flour discs. The solvent was allowed to evaporate and then 10 adult insects were introduced into each treatment. After 72 h, nutritional indices were calculated. Results indicated that nutritional indices were significantly varied as essential oil concentrations increased. In this study, C. copticum decreased RGR, RCR and ECI significantly higher than that of V. pseudo-negundo essential oil. Both of plant essential oils, with the same activity, increased FDI as the oil concentration was increased, showing high feeding deterrence activity against T. castaneum. Generally, antifeedant activity of C. copticum was more effective than V. pseudo-negund.