. ozone application has increased to control stored products pests in recent years due to development of insect resistance into current fumigants, trend of consumers to move away from residual chemicals and loss of suitable fumigants. The attractive aspect of ozone is that it decomposes rapidly (half-life of 20–50 minutes) to molecular oxygen without leaving any residue. Electrical generation of ozone eliminates the handling, storage and disposal problems of conventionally used post-harvest pesticides. These attributes make ozone an attractive candidate for controlling insects in stored grain. The aim of this study was to investigate the potential use of ozone as a new and safe method for controlling cowpea weevil, Callosobruchus maculatus and angoumois grain moth, Sitotroga cerealella. For this purpose, lethal effect of four concentrations (5780, 2737, 1767 and 1295 ppm) of ozone in three times (30, 60 and 120 minutes) on the all of developmental stages of C. maculatus , adults and eggs of S. cerealella was evaluated. Experiments were done three times and using factorial design in a randomized complete blocks. To study the penetration of ozone into grain mass, mortality of adults of C. maculatus and S. cerealella in different depths (30, 60 and 90 Centimeters) of cowpea and wheat mass was calculated in two concentrations (5780 and 2737 ppm) of ozone and three times (30, 60 and 120 minutes) of ozonation. Relationship between the number of lived insects, concentration of ozone and ozonation time was formulated using Excel software. Then, by a formula, approximate concentration of ozone was calculated in different depths of grain mass. Effect of different concentrations of ozone on germination of cowpea and wheat seeds was studied, then germination percent in ozonated seeds was compared to control. Additionally, to investigate the probable effect of ozone on oxidation of cowpea oil, malonaldehyde content of ozonated and control cowpeas was measured by TBA method and compared. Results showed that a concentration of 2737 ppm for two hours resulted in 100% mortality of adult, egg and young larvae and over 50% mortality of old larvae and pupa of C. maculatus . Adults and old larvae showed the lowest and highest sensitivity to ozone respectively. Ozone in 5780 and 2737 ppm for two hours caused 100% mortality of adults and over 80% mortality of eggs of S. cerealella . The effect of ozone on germination of cowpea and wheat seeds showed that 5780 ppm ozone for two hours decreased germination of seeds significantly but there was no significant differeces between germination of seeds that was ozonated with 2737 ppm ozone comparing to control in the same time. Measuring mortality in
