SIGNIFICANCE OF PASSIVE SORPTION OF ATMOSPHERIC WATER-VAPOR AND FEEDING IN WATER-BALANCE OF THE RICE WEEVIL, SITOPHILUS-ORYZAE

1. 1. A water budget and kinetics for gain and loss of water was determined for Sitophilus oryzae at four water vapor activities (avs). Water flux was determined by using tritiated water. 2. 2. Body water content was proportional to food water content and ambient water vapor activity. The quantity of food consumed was regulated by food water content and ambient av. 3. 3. Water imbibed with food and water passively sorbed from unsaturated ambient air constituted the major avenues of water gain. Sorption rates were proportional to av while transpiration rates were independent of av. 4. 4. Decrease in water gain associated with reduced feeding rates at high av were compensated for by increased sorption rates. 5. 5. Metabolic rate was independent of av and production of metabolic water insignificant relative to overall water exchange. © 1979.