1989 Volume 36 Issue 4 Pages 267-273
Effects of the microwave (MW, 2.45GHz) on stored-product insects at different developmental stages; Sitophilus zeamais (Sz), Sitophilus oryzae (So), Rhyzopertha dominica (Rd), Oryzaephilus surinamensis (Os), Tribolium castaneum (Tc) and Plodia interpunctella (Pi) and on the rice qualities were studied. The temperature in the host media (foods), husked rice for Sz, So, Rd and Pi, wheat for Os and wheat flour for Tc, during the MW treatments were recorded with a floroptic thermometer. The MW treatment could hardly kill the insects without heating the host media. The insects were killed effectively when the temperature of the host media increased more than 60°C, although the susceptibilities of the insects varied depending on species and developmental stages. The adults of So and Os and mature larvae of Pi were most tolerant followed by Rd adult>Pi pupa>Sz adult, Tc adult and Pi egg>Tc pupa, egg and mature larva in decreasing order. The increased moisture content of husked rice resulted in the higher mortality of Sz adult. All species and developmental stages of insects examined were killed by MW with 2.5kW output within 55s. The taste and qualities of husked rice treated with MW for 60s, when the average temperature of rice was ca. 75°C, were unaffected significantly during storage of 4 months at 15, 25 and 30°C. However, after 6 months, the tates of the treated rice stored at 15 and 25°C were more deteriorated than those of their untreated controls.
