Disinfestation of Rhyzopertha dominica (F.) using microwave heat treatment to the Malaysian paddy

Abstract

Dielectric spectroscopy was used to analyze Rhyzopertha dominica (F.) or lesser grain borer for microwave heat treatment to Malaysian paddy MR219. The temperature dependency of the dielectric properties of Rhyzopertha dominica (F.) and Malaysian paddy MR 219 were analyzed for the frequency range of 200 MHz - 20 GHz and for the temperature range of 24 °C - 65 °C. Four excited temperature points, i.e., 34 °C, 40 °C, 48 °C and 55 °C showed that these temperature points can absorb more microwave energy, thereby increasing the interior temperature of Rhyzopertha dominica (F.) significantly. Predictive model was developed to make relationship between the dielectric properties and related factors (i.e., temperature and frequency). At high temperature, the complex organic constituents of Rhyzopertha dominica (F.) were determined to be dielectrically inert. General equations that utilized frequency and temperature were developed to describe the dielectric properties of Rhyzopertha dominica (F.). Effects of ramp period and holding time to achieve higher mortality were analyzed. Observation results were analyzed to reach 100% mortality of Rhyzopertha dominica (F.).