The effect of nitrogen and carbon dioxide on eggs of Ephestia cautella (Walker) and E. kuehniella Zeller (Lepidoptera: Pyralidae)

Some eggs of Ephestia cautella (Wlk.) and E. kuehniella Zell. hatched after exposure to near 100% atmospheres of nitrogen (N 2 ) or carbon dioxide (CO 2 ) for up to 5 days at 15°C, 3 days at 20°C and 1 day at 25°C. The most tolerant age at the start of treatment at 25°C in E. cautella was 7–24 h after oviposition for CO 2 and 7–30 h for N 2 . Generally, hatch was lower in CO 2 than in N 2 whatever the exposure, and lower for E. kuehniella than for E. cautella . Considerably more eggs of E. cautella aged 30 and 42 h hatched after exposure to N 2 than to CO 2 , showing a toxic effect of CO 2 in the absence of oxygen. Eggs of both species treated with either CO 2 or N 2 hatched 1–2 days later than controls, regardless of age or percentage survival.