Abstract

Alternatives for the control of insect pests in grain processing and storage units are necessary to maintain the characteristics of the product and decrease environmental impact. Although the toxic effects of ozone on some insect pests of stored products are already known, there is little information about their effects inside the grain column. This study aimed to evaluate Rhyzopertha dominica (Fabr.) (Coleoptera: Bostrichidae) control by ozone gas in wheat grains. Ozone was applied at a concentration of 1.61 mg L^-1 and flow rate of 2.0 L min^-1 in wheat grains. Inside the grain column, insects were placed in plastic cages distributed at three different points: on the plenum (basis), middle part and surface. The toxicity results indicated that the periods of ozone exposure that were necessary to cause mortalities of 50 and 95% in adult R. dominica ranged from 8.69 to 13.08 h and from 11.28 to 18.11 h, respectively. Shorter lethal times were observed when the insects were distributed on the basis of the grain column. A decreased instantaneous growth rate of R. dominica was observed with an increased exposure period. There was a significant correlation between the instantaneous growth rate and the physical and physiological characteristics of wheat grain.

Key words: Storage, insecticidal fumigant, toxicity, instantaneous growth rate, ozone, wheat grains.