Effect of ozone gas against life stages of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) in laboratory and a storehouse

Effects of gaseous ozone on Ephestia kuehniella eggs, larvae, pupae and adults were evaluated in laboratory and storehouse trials. In laboratory, all life stages were freely exposed in a test chamber to five ozone concentrations (5, 10, 20, 50 and 100 ppm) for 24 h to assess mortality, and also development for the treated eggs, larvae and pupae, and the number of eggs laid by the treated adults. In a storehouse, the effect of ozone at 50 ppm on adults was evaluated in comparison with routine treatment (pyrethrin application) and untreated control. In laboratory, all tested ozone concentrations significantly increased mortality of all E. kuehniella stages, in comparison with untreated control; however, complete mortality was observed only for adults starting from ozone concentration of 50 ppm. Time needed for the eggs to hatch and the larvae to pupate was delayed by ozone treatments, starting from ozone concentration of 10 or 5 ppm, respectively. Moreover, ozone affected also the number of eggs laid by surviving adults in the 24 h following ozone treatment: egg hatching rate was significantly lower at all concentrations. In the storehouse trials, the ozone treatment at 50 ppm killed almost all exposed adults as the pyrethrin treatment. Therefore, the results from this study suggest that ozone can be considered as an effective alternative to the current routine spray of pyrethrins during spring and summer.