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Title: Susceptibility of various life stages of Rhyzopertha dominica (F.)(Coleoptera: Bostrichidae) to flameless catalytic infrared radiation

Author
item KHAMIS, MOSES - Kansas State University
item SUBRAMANYAM, BHADRIRAJU - Kansas State University
item Flinn, Paul
item DOGAN, HULYA - Kansas State University
item JAGER, ABIGAIL - Kansas State University
item GWIRTZ, JEFFREY - Kansas State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2010
Publication Date: 8/23/2010
Citation: Khamis, M., Subramanyam, B., Flinn, P.W., Dogan, H., Jager, A., Gwirtz, J.A. 2010. Susceptibility of various life stages of Rhyzopertha dominica (F.)(Coleoptera: Bostrichidae) to flameless catalytic infrared radiation. Journal of Economic Entomology. 103(4):1508-1516.

Interpretive Summary: The lesser grain borer is one of the most damaging insect pests of stored wheat in the US, and there are few insecticides that are registered for control of this pest. In collaboration with scientists at Kansas State University, we conducted experiments to determine the effectiveness of infra-red radiation to kill different stages of lesser grain borer inside wheat kernels using a catalytic heater operating on propane gas. The grain temperatures attained were influenced by wheat quantity, distance from the emitter, and exposure time. In general, higher grain temperatures were attained in 113.5 g of wheat as opposed to 227.0 g, at 8.0 cm from the emitter surface rather than at 12.7 cm, and during a 60 sec exposure compared to a 45 sec exposure. Old larvae were less susceptible to infrared radiation than young larvae. Probability of death was 94-100% for all life stages when the wheat was exposed for 1 minute at a distance of 8.0 cm from the emitter. These results show that flameless catalytic infra-red technology may be a viable option for disinfestation of stored wheat in the future.

Technical Abstract: In laboratory experiments, a flameless catalytic infrared emitter, fueled by propane, was used to disinfest hard red winter wheat containing different life stages of the lesser grain borer, Rhyzopertha dominica (F.), an economically important insect species associated with stored wheat in Kansas. The emitter generates infrared radiation in the 3-7 µm range. The life stages of R. dominica exposed to infrared radiation included eggs, larvae in different stages of development, pupae, and 2-wk-old adults. A non-contact infrared thermometer measured real-time grain temperatures during exposures of infested wheat to infrared radiation. The grain temperatures attained were influenced by wheat quantity, distance from the emitter, and exposure time, which in turn influenced effectiveness against various life stages of R. dominica. In general, higher grain temperatures were attained in 113.5 g of wheat as opposed to 227.0 g, at 8.0 cm from the emitter surface rather than at 12.7 cm, and during a 60 sec exposure compared to a 45 sec exposure. Logistic regression indicated the probability of death of various life stages of R. dominica was temperature-dependent. The log odds ratios showed old larvae were less susceptible to infrared radiation than young larvae. About 99 to 100% mortality of all R. dominica life stages occurred when using 113.5 g of wheat, exposed for 60 sec at a distance of 8.0 cm from the emitter, resulting in mean wheat temperatures of 108 to 114oC. These promising results show flameless catalytic infrared technology to be a viable option for disinfestation of stored wheat.