Controlling Maize Weevil (Sitophilus zeamais) Life Stages at a Moderate Temperature Using Microwave Energy

The objective of this study is to evaluate the effect of microwave energy in controlling life stages (egg, larvae, pupa, and adults) of maize weevil (<i>Sitophilus zeamais</i>) and validate the optimum condition for eliminating the pest in maize grain. Maize samples (300 g) each at 10, 14, and 18% w.b. initial moisture contents (IMCs) were infested with various life stages of <i>S. zeamais</i> and exposed to microwave energy (2.45 GHz) at 300 W to raise the grain's temperature to 50 °C, holding for different times of 0, 1, 3, and 5 min. Among the life stages of <i>S. zeamais</i>, the egg stage was the most susceptible to microwave energy, whereas the adult stage was the least susceptible. Complete eradication of all life stages of <i>S. zeamais</i> can be achieved by using microwave energy at a temperature of 50 °C for 5 min at all initial moisture content levels. Germination rate was significantly (<i>p</i> < 0.05) lower in the microwave-treated grains compared to the untreated ones. The partial least squares (PLS) validation model indicated that microwave heating of grain with 14% moisture content at 50 °C for 1 min was the most effective method for eliminating <i>S. zeamais</i> life stages and maintaining the germination rate of the grain, which could be further explored for industrial applications in the maize processing.