Radio frequency (RF) control of red flour beetle (Tribolium castaneum) in stored rapeseeds (Brassica napus L.)

Abstract

Absolute and relative mortalities of red flour beetle (Tribolium castaneum) infesting the rapeseeds of a small (196.3 cm3) and a large (1766 cm3) volumes during radio frequency (RF) heating (1.5 kW, 27.12 MHz) were determined at different end temperatures (30–80 °C) and initial seed moisture contents (5%, 7%, 9%, and 11% wet basis). 100% absolute and relative mortalities of the adult insects were achieved at 80 °C for the small volume of the seeds at all moisture contents (MCs) and at 60 °C and 9% and 11% MCs, and 70 °C and 5% and 7% MCs for the large volume. Over 80% and 96% of the absolute and the relative mortalities of the adult insects were achieved at over 60 °C for both volumes of the seeds. 100% mortalities of larvae infesting the small and the large volume seeds were achieved at 55 °C at all MCs. Germination, major and minor axes, roundness, colour of the seeds and qualities of the rapeseed oil were not affected significantly by RF treatment temperature at entire MCs. Therefore, a complete mortality of the red flour beetle infesting the rapeseeds with acceptable thermal degradation to qualities of the seeds could be achieved at under 60 °C by the RF treatment with a proper design of RF disinfestation.