Modeling and optimization of the insecticidal effects of Teucrium polium L. essential oil against red flour beetle (Tribolium castaneum Herbst) using response surface methodology

The utilization of natural materials in the post-harvest process of agricultural products is necessary for the production of safe food. In recent years, the use of essential oil extracted from aromatic plants has shown significant potential for insect pest management. Toxicity and antifeedant effects of essential oil isolated from aerial parts of Teucrium polium L. have been investigated against the red flour beetle, Tribolium castaneum Herbst, as one of the most detrimental insect pests of post-harvest cereals in the present study. The chemical profile of this oil was also assessed by gas chromatography-mass spectrometry (GC-MS) and lycopersene (26.00%), dodecane (14.78%), 1,5-dimethyl decahydronaphthalene (9.27%) and undecane (7.18%) were identified as main components. For evaluation of the fumigant toxicity and antifeedant effects using multiple regression analysis, a quadratic polynomial and linear equation were obtained, respectively. Adequacy and accuracy of the fitted models were checked through analysis of variance. T. polium essential oil exhibited significant fumigant toxicity on the T. castaneum adults and based on modeling using RSM, the concentration of 20 µl/l and 72 min exposure time was calculated as the optimum conditions for 97.97% mortality with 87.8% desirability. A concentration of 14.13 µl/l was also estimated as the optimum value for 94.66% Feeding Deferens Index with 92% desirability. The mortality and anti-nutritional effect, in general, increased with increasing of exposure times and the essential oil concentrations. Results designated a great potential of T. polium essential oil for management of the red flour beetle. Further, it was found that the Response Surface Methodology was a promising method for the prediction of these bio-effects.