Control of Sitophilus oryzae infestation of stored wheat: An ecosystem model of the use of aeration

Populations of the grain storage insect pest Sitophilus oryzae (L.) may be controlled by manipulating the microclimates of grain bulks in which they occur. In this paper a validated mathematical model of the heat and moisture transfer phenomena that occur in aerated grain bulks is presented, and is combined with a population model of S. oryzae. The composite model predicts that blowing cold night air through grain bulks severely curtails the population growth of weevils. Furthermore, the composite model indicates that there is an optimum aeration strategy that results in the lowest number of insects. Aeration with ambient air is also shown to render the population dynamics of S. oryzae relatively insensitive to both initial grain moisture content and temperature. The results are discussed with reference to the physics of heat and moisture transfer between the air-water mixture and the hygroscopic grain.