Two models of grain temperatures and insect populations in stored wheat

Stored grain temperatures and population dynamics of rusty grain beetles, C ryptolestes ferrugineus (Stephens), predicted by a hot spot model, which in cluded feedback from the insect model to the temperature model, and a spati al model, which did not include that feedback, were compared. For an initia l grain temperature of 30 degreesC and an initial population of 10,000 adul t insects in stored grain at Winnipeg, Canada, the hot spot model predicted a maximum of 120 adults/kg of wheat at the center of the grain bulk toward the end of fall and a maximum temperature of 39 degreesC. The spatial mode l predicted an adult population of 500 adults/kg of wheat and no increases in temperatures. For the same simulation conditions but using weather data for Topeka, Kansas, the hot spot model predicted a maximum of 150 adults/kg of wheat at the center of the bulk in fall, while the spatial model predic ted a maximum of 800 adults/kg. The hot spot model is closer to reality tha n the spatial model because it simulates the effects of variable heating ar ound the bin wall, insect heat production, and insect movement.