Effects of Time of Aeration, Bin Size, and Latitude on Insect Populations in Stored Wheat: A Simulation Study

Abstract

A spatial model of Cryptolestes ferrugineus (Stephens) population dynamics and bin temperature was used to simulate effects of time of aeration, bin size, and latitude on C. ferrugineus density in stored wheat. In unaerated grain, densities of C. ferrugineus were predicted to be much greater in wheat stored in Oklahoma than in Kansas or South Dakota and reach greater densities in 272.2-T (10,000 bu) than in 81.6-T (3,000 bu) bins. Automatic aeration controllers (fans turned on when outside air was 10ºC lower than grain temperature) suppressed C. ferrugineus population growth better than manual aeration starting in November. Automatic aeration also worked better when started at grain harvest rather than waiting until 1 September. In Oklahoma, automatic aeration starting at harvest was the only aeration strategy that prevented C. ferrugineus from exceeding 2/kg. Average fan hours to cool the grain to 10ºC using automatic control starting at harvest was 270 h for 272.2-T bins and 220 h for 81.6-T bins. Starting automatic aeration at harvest added an additional 30 h. This small increase in fan hours resulted in much greater C. ferrugineus suppression, especially in latitudes similar to those of Oklahoma and Kansas. In temperate climates, automatic aeration controllers should greatly reduce the need for chemical control.