Effect of different controlled atmosphere gas compositions on the developmental time of Cadra cautella pupae at different temperatures

Abstract

Low oxygen and/or high carbon dioxide environments (hypoxic, anoxic or hypercarbic atmospheres) can cause a delay in insect development, the length of which depends on the exposure time, gas concentration, environmental factors, species, etc. Therefore, in this study, delay in development in 0–72 h old pupae of Cadra (=Ephestia) cautella was investigated by exposing them to two low oxygen (1% and 3%) atmospheres supplemented with high carbon dioxide (95% and 85%) balanced with nitrogen for 6–112 h at 20 °C, 25 °C and 30 °C and 65% relative humidity. Development-delaying effects of controlled or modified atmospheres (MA) were strongest at 20 °C, followed by 25 °C and 30 °C. The shortest exposure time at which delay in development was statistically meaningful was 24 h. Development-delaying effects of both MAs were of similar pattern. When compared to control groups, delay in development was in the range of 2.03–9.64 d at 20 °C, 0.19–3.72 d at 25 °C, and 0.02–2.77 d at 30 °C. Cadra cautella pupae, which were exposed to 1% oxygen with 95% carbon dioxide (balance with nitrogen) at 20 °C for 64 h, could still hatch 24 d after the treatment in comparison to control groups in which pupal eclosion was max. 16 d. Therefore in MAs applications, delay in development could be an important issue to consider for controlling stored-products pests, especially at lower temperatures.