Modeling of the toxicity of Eucalyptus globulus Labill essential oil against red flour beetle, Tribolium castaneum Herbst

Abstract

Although the application of synthetic chemicals is the main method in the management of insect pests, their overuse has led to public concerns about environmental pollution, threats to human health, and acute and chronic toxicity on non-target organisms. Plant essential oils have introduced as healthy, available, and effective alternatives to detrimental chemicals in recent years. Further, it is necessary to predict the exact amount of required pesticide to save costs and determine the optimal conditions for achievement to the best outcomes. Accordingly, the toxicity of Eucalyptus globulus Labill essential oil against the adults of a cosmopolitan pest Tribolium castaneum Herbst (red flour beetle) along with its modeling and optimization was assessed using Response Surface Methodology (RSM). The coefficients of the essential oil concentration and time as independent variables are positive, showing their increase results in the augmentation of insect pest mortality. E. globulus essential oil showed prospective concentration-time dependent fumigant toxicity against T. castaneum. A quadratic polynomial equation was achieved for the toxicity of E. globulus essential oil using multiple regression analysis: 7.33413 + 0.20191A + 0.47313B + 4.64054E-003AB + 0.016349B2, in which A and B are the exposure time and essential oil concentration. The accuracy of the introduced model was approved through the analysis of variance. Results of the optimization indicated that 45.50 μl/l of essential oil and 72.00 h-exposure time would be adequate to achieve 92.45% mortality of T. castaneum. According to the results of current study, E. globulus essential oil has high potential in the management of T. castaneum and the Response Surface Methodology (RSM) is a suitable method to the optimization and modelling of this bio-effect.