Antifeedant activity of Descurainia sophia and Thuja orientalis extracts against Tribolium castaneum (Coleoptera: Tenebrionidae)

Antifeedant activity of the aqueous and hydroalcoholic extracts of leaves of Descurainia sophia L. and Thuja orientalis L. were tested against adults of Tribolium castaneum (Herbst). The experiment was 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 under dark condition, at 27 ± 1 °C and 60 ± 5% RH. Ten microliter portions of each extract at concentrations (0.25-2.0%) was spread evenly on the flour discs. Results indicated that nutritional indices were significantly affected as extract concentrations increased. In this study extracts from T. orientalis decreased RGR, RCR and ECI significantly more than that of D. sophia. In addition, hydroalcoholic extracts decreased RGR, RCR and ECI significantly more than those by aqueous extracts. Both of plant extracts increased FDI as the extract concentrations were increased, showing high feeding deterrence activity against T. castaneum. Generally, antifeedant activity of T. orientalis was greater than D. sophia and hydroalcoholic extracts were more effective than aqueous extracts.