Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/6/2010
Publication Date: 1/15/2011
Citation: Khamis, M., Subramanyam, B., Flinn, P.W., Dogan, H., Gwirtz, J.A. 2011. Susceptibility of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) life stages to flameless catalytic infrared radiation. Journal of Economic Entomology. 104(1): 325-330. http://dx.doi.org/10.1603/EC10074. Interpretive Summary: The red flour beetle is a common pest of stored wheat. Few new insecticides are being developed for stored-grain insect control, which increases the chances that insecticide resistance will develop. A catalytic heater using propane gas can be used to produce heat that can kill insects in grain. 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 red flour beetle in stored wheat. Grain temperature was a function of exposure time, distance from the heat source, and amount of grain. All life stages of the red flour beetle were killed after a 60 second exposure at a distance of 8.0 cm (3.1 inches)from the emitter using 113.5 g (4 ounces) of wheat. The mean grain temperatures ranged from 107 to 111°C (225 to 232°F. Pupae were the least susceptible stage, followed by eggs, adults, and larvae. These results indicate that flameless catalytic infra-red technology may be a possible option for controlling insects in stored grain in the future.
Technical Abstract: The susceptibility of various life stages of the red flour beetle, Tribolium castaneum (Herbst), a pest of stored wheat, to flameless catalytic infrared radiation in the 3 to 7 µm range was evaluated in the laboratory. Immature stages were collected from flour infested with T. castaneum adults only for 1 d. Stages collected after 1 d represented eggs (collected on day 0); those collected after 7, 14, and 21 d from day 0 represented larvae in different developmental stages, while those collected after 24 d represented pupae. Adults (2-wk-old) were collected after 42 d. Each of these stages was exposed for 45 or 60 s in 113.5 or 227.0 g of wheat at a distance of 8.0 or 12.7 cm from a bench top infrared emitter. The mean temperatures attained during exposures were measured continuously using a non-contact infrared thermometer connected to a computer. The mean grain temperatures attained increased with an increase in exposure time, and were inversely related to distance from the emitter. Grain quantity least influenced mean temperatures attained. Pupae were the least susceptible stage and larvae collected after 7 d were the most susceptible stage. Variation in probability of death of various life stages decreased with an increase in mean grain temperatures attained. All life stages were killed after a 60 s exposure at a distance of 8.0 cm from the emitter in 113.5 g of wheat where the mean ± SE temperatures attained ranged from 107.6 ± 1.2 to 111.4 ± 0.5°C. Our laboratory results using small grain quantities and short exposure times showed that flameless catalytic infrared radiation can be a valuable tool for managing insects in stored organic and non-organic wheat.