Radio frequency (RF) dielectric heating was tested to control Cryptolestes ferrungineus S. in the bulk wheat samples (ca.152 g, dia. = 50 mm, ht.= 100 mm) at the MCs (%, w. b.) of 12, 15, and 18 using a pilotscale RF heater (1.5 kW, 27.12MHz) in the batch mode. When the temperature of the hottest spot (geometric center) of the sample, TH was at 80°C, all the adult insects were found dead at the cold spots, near bottom-wall, at 50.7°C to 56.0°C depending up on the wheat MCs. The temperatures of the insect-slurries higher than that of the bulk wheat by 0.8°C to 15.1°C indicated the selective heating of the insects. The mortalities of adult insects were almost constant within the quarantine period, QP1 (5 wk). The elapsed time during QP1 had a significant effect only on the insects' mortalities with the wheat at 12% MC. The wheat MC had only marginal significance on the absolute mortalities of insects. The larvae were completely destroyed at temperatures between 55°C and 60°C. The complete mortality of all life stages (eggs, larvae, pupae, and adults) of the insect was achieved at TH = 80°C without any emergence of the insects during QP2 (8 wk). The RF treatment enhanced the germination of the wheat kernels at 12% MC while it was decreased by 2% to 33% depending up on the wheat MC, and the treatment temperature. Temperature had no significant effect on the falling numbers, and the yields of flour, bran, and shorts, and the peak-bandwidth and the MC of the wheat, and the flour protein values. The means of the mixing-development-time deferred from the controls mostly for the wheat at 15% MC and TH = 70°C, and 18% MC and TH = 70°C and 80°C. The mean-peak-height and the color values varied between 4% and 16%, and 3% and 6% off the controls depending up on the temperatures. The uniform temperature of 60°C should be enough to control all life stages of the insect completely with a little or no changes in the important product quaities and germination of the wheat at MCs safe for the storage. Future research mainly focused on better estimation of the insect-to-grain electric field intensities is essential.
2. Ponomaryova, I., et al., "Insect control by radio-frequency high-strength electric fields," 2009 6th International Conference on Electrical Engineering, Computing Science and Automatic Control, CCE 2009, 1-5, Toluca, Nov. 10-13, 2009.
3. Vadivambal, R., D. S. Jayas, and N. D. G. White, "Determination of mortality of di®erent life stages of Tribolium castaneum (Coleoptera: Tenebrionidae) in stored barley using microwaves," Journal of Economic Entomology, Vol. 101, No. 3, 1011-1021, 2008.
4. Vadivambal, R., D. S. Jayas, and N. D. G. White, "Wheat disinfestation using microwave energy," Journal of Stored Products Research, Vol. 43, 518-514, 2007.
5. Wang, S., J. Tang, T. Sun, E. J. Mitcham, T. Koral, and S. L. Birla, "Considerations in design of commercial radio frequency treatments for postharvest pest control in in-shell walnuts," Journal of Food Engineering, Vol. 77, 304-312, 2006.
6. Soproni, V. D., F. I. Hathazi, M. N. Arion, C. O. Molnar, and L. Bandici, "Aspects regarding the adapting and optimization of mixed drying systems microwave-hot air for the processing of agricultural seeds," PIERS Proceedings, 210-213, Beijing, China, Mar. 23-27, 2009.
7. Shrestha, B. and O. D. Baik, "Radio frequency (RF) selective heating of stored-grain insects at 27.12MHz - A feasibility study," Biosyst. Eng., Vol. 114, 195-204, 2013.
8. Cofie-Agbior, R., R. Muir, N. Sinha, and P. G. Fields, "Heat production by adult Cryptolestes ferrugineus (Stephens) of different ages and densities," Postbarvest Biol. Technol., Vol. 7, 371-380, 1996.
9. Nelson, S. O., "Dielectric spectroscopy in agriculture," J. Non-Cryst. Solids, Vol. 351, 2940-2944, 2005.
10. Guo, W., X. Wu, X. Zhu, and S. Wang, "Temperature-dependent dielectric properties of chestnut and chestnut weevil from 10 to 4500 MHz," Biosyst. Eng., Vol. 110, 340-347, 2011.
11. Ikediala, J. N., J. Tang, S. R. Drakeand, and L. G. Neven, "Dielectric properties of apple cultivars and codling moth larvae," Transactions of the American Society of Agricultural Engineers , Vol. 43, No. 5, 1175-1184, 2000.
12. Rashkovan, V. M., N. A. Khizhnyak, A. V. Basteev, L. A. Bazyma, L. N. de Rivera, and I. A. Ponomaryova, "Interaction of electromagnetic waves with granular product and insects," J. Microw. Power Electromagn. Energy, Vol. 36, No. 4, 225-235, 2003.
13. Hamid, M. A. K., C. S. Kashyap, and R. V. Cauwenberghe, "Control of grain insects by microwave power," J. Microwave Power, Vol. 3, No. 3, 126-135, 1968.
14. Wang, S., M. Y. G. Monzon, J. Tang, E. J. Mitcham, and J. W. Armstrong, "Temperature-dependent dielectric properties of selected subtropical and tropical fruits and associated insect pests," Transactions of the American Society of Agricultural Engineers, Vol. 48, No. 5, 1873-1881, 2005.
15. Wang, S., J. Tang, J. A. Johnson, J. E. Mitcham, J. D. Hansen, G. Hallman, S. R. Drake, and Y. Wang, "Dielectric properties of fruits and insect pests as related to radio frequency and microwave treatments," Biosyst. Eng., Vol. 85, No. 2, 201-212, 2003.
16. Nelson, S. O., P. G. Bartley, Jr., and K. C. Lawrence, "RF and microwave dielectric properties of stored-grain insects and their implications for potential insect control," Transactions of the American Society of Agricultural Engineers, Vol. 41, No. 3, 685-692, 1998.
17. Wang, S., J. Tang, R. P. Cavalieri, and D. C. Davis, "Differential heating of insects in dried nuts and fruits associated with radio frequency and microwave treatments," Transactions of the American Society of Agricultural Engineers, Vol. 46, No. 4, 1175-1182, 2003.
18. Wang, S., M. Monzon, J. A. Johnson, E. J. Mitcham, and J. Tang, "Industrial-scale radio frequency treatments for insect control in walnuts: II. Insect mortality and product quality," Postharvest Biol. Technol., Vol. 45, No. 2, 247-253, 2007.
19. Johnson, J. A., K. A. Valero, S. Wang, and J. Tang, "Thermal death kinetics of red flour beetle (Coleoptera: Tenebrionidae)," J. Econ. Entomol., Vol. 97, No. 6, 1868-1873, 2004.
20. Armstrong, J. W., J. Tang, and S. Wang, "Thermal death kinetics of mediterranean, malaysian, melon, and oriental fruit fly (Diptera: tephritidae) eggs and third instars," J. Econ. Entomol., Vol. 102, No. 2, 522-532, 2009.
21. Abbott, W. S., "A method of computing the effectiveness of an insecticide," J. Am. Mosq. Control. Assoc., Vol. 3, No. 2, 302-303, 1925.
22. Fields, P. G., "The control of stored-product insects and mites with extreme temperatures," Journal of Stored Products Research, Vol. 28, 89-118, 1992.
23. Nelson, S. O., "Review and assessment of radio-frequency and microwave energy for stored-grain insects control," Transactions of the American Society of Agricultural Engineers, Vol. 39, 1475-1485, 1996.
24. Nelson, S. O., "Use of microwave and lower frequency RF energy for improving alfalfa seed germination," Journal of Microwave Power, Vol. 11, No. 3, 271-277, 1976.
25. Nelson, S. O. and E. R. Walker, "Effect of radio frequency electrical seed treatment," Agr. Engr., Vol. 42, No. 12, 688-691, 1961.