Effects of microwave radiation to the bean weevil Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae)

Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae) is a pest that causes economic losses particularly on dry beans. Various control methods, especially those involving chemical treatments, have been successfully used against this pest. However, excessive use of chemicals poses resistance problems in insects and also threatens environmental and human health. For this reason, producers and researchers have been turning toward alternative control methods. One such method is the use of microwave radiation. This technique results in minimal product loss while significantly reducing pest populations. In this study, the effects of different microwave levels on A. obtectus, a storage pest of beans, were determined. In the trials, 7 different exposure times (5, 10, 20, 40, 60, 80, and 100 seconds) and 5 different power levels (120, 350, 460, 600, and 700 watts) were applied to determine the mortality rate of the pest. The number of pest deaths was recorded. The laboratory production of this pest and the experiments were conducted in a room at 25±1 °C and 60±5% relative humidity. The results showed that mortality rates increased both with longer exposure to low radiation levels (120 watt, 100 sec., 73%; 350 watt, 60 sec., 100%) and with shorter exposure to high radiation levels (700 watt, 5 sec., 91%; 10 sec, 95%; 20 sec., 100%). The findings suggest that this method can be recommended as an alternative approach for controlling A. obtectus.