Comparative susceptibility of Corcyra cephalonica (Lepidoptera: Pyralidae) eggs to carbon dioxide and nitrogen at different temperatures

The aim of this study was to evaluate the susceptibility of the egg stage of the rice moth Corcyra cephalonica to modified atmospheres (MAs) enriched with CO2 or N2 at 25, 30 and 35 °C combined with various exposure times. The tested modified atmospheres containing CO2 were 20% CO2, 16% O2 and 64% N2; 40% CO2, 12% O2 and 48% N2; 60% CO2, 8% O2 and 32% N2 and 80% CO2, 4% O2 and 16% N2. The tested modified atmospheres containing N2 were 97% N2 and 3% O2 and 98% N2 and 2% O2. The results showed that the hatchability responding to modified atmospheres enriched with either CO2 or N2 decreased significantly with an increase in exposure time, gas content (%) and temperature. All tested combinations provided complete (100%) egg control in less than 4 days. Based on 100% mortality, shorter exposures were obtained with 80% CO2 than with N2 at most tested temperatures. The modified atmospheres enriched with 98% N2 were more effective than 97% N2 against C. cephalonica eggs, especially at 35 °C. It is recommended to use high levels of CO2 in air (80%) and N2 (98%) in controlling 0-24-h-eggs of C. cephalonica within 24-36 h for CO2 and 18-72 h for N2.