EFFECT OF PNEUMATIC CONVEYING OF WHEAT ON MORTALITY OF INSECTS

The movement of stored hard red spring wheat by a pneumatic conveyor was evaluated for control of the two most common stored-product insect species. Wheat was infested with adults of the rusty grain beetle, Cryptolestes ferrugineus (Stephens) and the red flour beetle, Tribolium castaneum (Herbst). Infested wheat at moisture contents of 14, 17, and 20% was conveyed at two flow rates of 3.5 and 5.0 t/h (3.85 and 5.5 ton/h). Adult insect mortalities as high as 98% for both the insect species were obtained without causing any statistically significant loss of germination. For the internally feeding immature stages of C. ferrugineus, mortalities varied from 35% to 85% at a flow rate of 5.0 t/h (5.5 ton/h). Samples taken from the three sampling ports along the grain path indicated that most of the mortality of adult insects occurred due to the abrasive action in the longest conduit path of the conveyor. The effect of flow rate on the mortality rate was statistically insignificant, but mortality increased with decreased moisture content of the grain.