Responses of Codling Moth (Lepidoptera: Tortricidae) Life Stages to High Carbon Dioxide or Low Oxygen Atmospheres

Abstract

Eggs, mature larvae, diapausing larvae, pupae, and adult stages of codling moth, Cydia pomonella (L.), were exposed to two controlled atmospheres at 25°C and either 60 or 95% RH. The atmospheres used were either a simulated combustion atmosphere (0.5% O2, 10% CO2, balance nitrogen) such as that produced by an exothermic generator fueled with methane or propane, or a 60% CO2 in air atmosphere. Mortality data were converted to logits and multiple regression analyses of logit versus time were performed for each life stage. LT95’s were estimated from the regression models. The trend from least to most tolerant stage was: eggs, adults < pupae < mature larvae < diapausing larvae. Atmospheres at 60% RH killed all life stages except eggs more quickly than those at 95% RH; for eggs, the difference was not significant. Except for pupae, the carbon dioxide atmospheres caused faster mortalities than the low oxygen atmospheres. LT95’s for eggs were <2 d, while LT95’s for larvae ranged from 7 to 19 d. Diapausing larvae were killed with 60% CO2 atmosphere in 13–24 d, whereas with the low oxygen atmosphere approximately 70% mortality was attained after 18 d at 60% RH, and 60% mortality was attained after 42 d at 95% RH.