The effect of ozone gas, an alternative to conventional fumigants on life stages of Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) and their effect on chemical properties of wheat flour

Abstract

The rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) is a harmful insect pest for grains in storage systems. However, there is a lack of available data on the effect of ozone on rice moth. In this study, we assessed the ozone at concentrations of 1.0, 3.0, and 5.0 g/m3 for six-time intervals (0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 h) on the mortality of insect life stages as well as pupation and adult emergence. The results showed that for all stages, the percent of mortality increased with increasing concentration and exposure time with 5.0 g/m3 and 5.0 h of exposure time resulted in 100.0% egg mortality. The highest mortality of treated larvae (89.1%) and pupae (96.2%) resulted after 5.0 h exposure to 5.0 g/m3 of ozone. Also, the results showed that the treated adults were more sensitive to ozone than the three other stages. A complete adult mortality was achieved by all concentrations of ozone at the following exposure times, 5.0 h after 1.0 day of treatment, 4.0 h after 2.0 days of treatment and 2.0 h after 3.0 days of treatment. Beside the effect on mortality, ozone suppressed the pupation and adult emergence from treated immature stages. The chemical analysis of treated wheat flour showed a slight decrease in protein, fat, carbohydrate, moisture and fibre and a slight increase in ash contents compared with untreated wheat flour. Our findings suggest that ozone can be effectively used for the control of C. cephalonica in stored wheat flour.