Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2010
Publication Date: 7/1/2011
Publication URL: http://ddr.nal.usda.gov/bitstream/10113/50395/1/IND44601910.pdf
Citation: Khamis, M., Subramanyam, B., Dogan, H., Flinn, P.W., Gwirtz, J.A. 2011. Effects of flameless catalytic infrared radiation on Sitophilus oryzae (L.) life stages. Journal of Stored Products Research. 47(3):173-178. http://dx.doi.org/10.1016/j.jspr.2010.11.002.. Interpretive Summary: The rice weevil causes a great deal of damage to stored wheat in the USA because the immature stages develop inside the kernel and are difficult to control. There are few insecticides that are registered for control of this pest, which increases the chances that insecticide resistance will develop. A catalytic heater using propane gas can be used to produce infra-red heat that can kill insects that are inside wheat kernels. In collaboration with scientists at Kansas State University, we conducted experiments to determine the effectiveness of infra-red radiation to kill different stages of the rice weevil inside wheat kernels. The grain temperatures attained were influenced by wheat quantity, distance from the emitter, and exposure time. Complete mortality of all stages of the rice weevil was achieved at 8.0 cm (3 inches) from the emitter using 113.5 grams (4 ounces) of wheat during a 60-second exposure. Eggs were least susceptible to the treatment, followed by adults inside kernels, larvae, and adults outside of kernels. These results show that flameless catalytic infra-red technology may be a viable option for disinfestation of stored wheat in the future.
Technical Abstract: A laboratory bench top flameless catalytic infrared emitter was evaluated against all life stages of the rice weevil, Sitophilus oryzae (L.), an insect species associated with stored wheat. The infrared radiation emitted was in the 3 to 7 µm range. A non-contact infrared thermometer measured grain temperatures instantaneously during exposures of infested wheat. Insect mortality was a function of final grain temperature attained. In general, higher grain temperatures were attained when using 113.5 versus 227.0 g of wheat, and at 8.0 cm from the emitter versus 12.7 cm, and during a 60 sec exposure versus a 45 sec exposure. Complete mortality of all life stages of S. oryzae was achieved at 8.0 cm from the emitter using 113.5 g of wheat, during a 60-sec exposure, and the mean grain temperatures attained ranged from 108.4 to 111.8°C. The log odds ratio tests showed that eggs (0-day old) were the least susceptible to infrared radiation, followed by adults within kernels (28-day old), pupae (24-day old), young larvae (7-day old), larvae that were 14 to 21 days old, and adults (42-day old). These data using small amounts of grain indicate infrared radiation from the flameless catalytic emitter to be a viable option for disinfesting wheat containing various ages of S. oryzae.