Directional flow of summer aeration to manage insect pests in stored wheat

Field trials were conducted in metal wheat storage bins to determine whether pressure aeration, pushing ambient air from the bottom, or suction aeration, pulling air down from the top, would be more efficient at cooling the wheat mass and thereby limiting insect population growth. Aeration was accomplished at an approximate airflow rate of 0.22 to 0.31 m3/min/t, and was done by adjusting thermostatic controllers to operate the aeration fans when ambient temperatures fell below specified thresholds. Summer and autumn cooling cycles using suction aeration cooled the warmest part of the bin, the top of the grain mass, first, which resulted in lower overall wheat mass temperatures compared to pressure aeration, where the top of the grain mass always remained warmer than with suction aeration. This cooling effect was most pronounced in the upper surface of the grain mass, and insect pest populations as measured by pitfall traps were consistently lower in bins with suction versus pressure aeration. Results seem to indicate that suction aeration would be more beneficial than pressure aeration for controlling insect pests in wheat stored in the southern plains of the United States.