Influence of cold plasma on mortality rate of different life stages of Tribolium castaneum on refined wheat flour

Red flour beetles, Tribolium castaneum (Herbst) are a major problem in packed refined wheat flour. Cold plasma is an emerging method which can be used to control the insects in stored food products. The effect of plasma on egg, larva and adult stages of T. castaneum was studied via three variables i.e. voltage, exposure time and distance between plasma electrodes. An experiment was designed and optimization of treatment conditions was carried out by response surface methodology. Twenty combinations of variables at different levels were experimented to analyse the response. Predictive equation for the mortality of insect stages were derived as a second order polynomial equation by quadratic model fitting at 95% confidence level. Interactive effects between independent variables were studied using 3D surface plot graphs. In all flour beetles' stages, 100% mortality can be achieved depending on plasma exposure time and plasma intensity. Optimum effect of plasma in controlling all stages of T castaneum was found to be at 2500 V for 15 min at 3.7 cm distance between electrode. It could be a promising nonchemical, nonthermal method for integrated pest management in stored food products. (C) 2018 Elsevier Ltd. All rights reserved.