Factors influencing effectiveness of flameless infrared radiation in disinfesting stored wheat

Alternative non-chemical technologies are needed in light of consumers’ demand for food free of pesticide residues and development of resistance in stored-grain insects to traditionally used pesticides. Flameless catalytic infrared radiation technology (www.catalyticdrying.com) is one such green technology for disinfesting stored grain. The effectiveness of a bench top infrared radiation in controlling three stored-grain insects in wheat was evaluated. Immature and adult life stages of the rice weevil, lesser grain borer, and red flour beetle were exposed to infrared radiation. The intensity of infrared heat was modulated by varying wheat quantity (113.5 and 227.0 g), distance from heater surface (8.0 and 12.7 cm) and exposure time (45 and 60 sec). Temperature of wheat during exposure was measured at 1-sec interval using an infrared thermometer connected to a laptop computer. The age structures of internally developing stages of the rice weevil and lesser grain borer were determined by radiographing kernels using a Faxitron X-ray and Skyscan 1072 for X-ray microtomography units. The temperature attained was greater in 113.5 g of wheat, irrespective of the distance from heater and exposure time. Similarly, higher temperatures were attained when wheat was closer to the heater source and at higher exposure times. Insect mortality of each species was related to temperatures attained as a function of grain quantity, distance from heater, and exposure time. In general, mortality tended to decrease with increasing age.