ECOLOGY OF STORED GRAIN IN THE CANADIAN PRAIRIES: I. THE DISTRIBUTION AND SIZE OF A LOW DENSITY POPULATION OF CRYPTOLESTES FERRUGINEUS (COLEOPTERA: CUCUJIDAE)

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Abstract
Two metal granaries each containing 27.3 tonnes of dry wheat (13–14% m.c.) were artificially infested with Cryptolestes ferrugineus (Stephens) and sampled for up to 4 years to determine fluctuations in insect density as influenced by changes in grain temperature and moisture content during storage. Density remained low (fewer than 5 insects/kg) throughout the period of study. Most insects were found at the floor near the wall on the south side of the granary. The temperature in the centre of the grain mass ranged from −5° to 22 °C during the 4 years. During a single season, moisture content varied as much as 5% at the centre near the surface of each grain mass, but did not vary more than 1% at other locations. In the first year of storage, the viability of the wheat ranged from 80% to 96%, and after 3 years in storage, 68% to 100%. Since no significant change was recorded in the temperature, moisture content, or germination of the wheat in the granaries, it was concluded that the biological activity of a low density population of C. ferrugineus does not initiate heating that occasionally occurs in farm-stored grain in Canada.