TWO MODELS OF GRAIN TEMPERATURES AND INSECT POPULATIONS IN STORED WHEAT

Abstract

Stored grain temperatures and population dynamics of rusty grain beetles, Cryptolestes ferrugineus (Stephens),predicted by a hot spot model, which included feedback from the insect model to the temperature model, and a spatial model,which did not include that feedback, were compared. For an initial grain temperature of 30C and an initial population of10,000 adult insects in stored grain at Winnipeg, Canada, the hot spot model predicted a maximum of 120 adults/kg of wheatat the center of the grain bulk toward the end of fall and a maximum temperature of 39C. The spatial model predicted anadult population of 500 adults/kg of wheat and no increases in temperatures. For the same simulation conditions but usingweather data for Topeka, Kansas, the hot spot model predicted a maximum of 150 adults/kg of wheat at the center of the bulkin fall, while the spatial model predicted a maximum of 800 adults/kg. The hot spot model is closer to reality than the spatialmodel because it simulates the effects of variable heating around the bin wall, insect heat production, and insect movement.