Meeting Abstract
Insect chill tolerance depends on the ability to withstand alterations in cellular homeostasis caused by low temperature exposure. Decreased oxygen availability (hypoxia) is known to interact with low temperature stress resistance, often improving insect survival. Here, we investigated whether the low temperature tolerance of larvae of a Lepidopteran chill susceptible pest, Thaumatotibia leucotreta, is affected by oxygen availability by measuring metabolic rate, critical thermal minimum (CTmin), supercooling point (SCP) and changes in 43 metabolites under varying oxygen conditions. The critical oxygen partial pressure (Pcrit) was determined to be 4.5 kPa, below which metabolic rate was suppressed. Altering the oxygen availability did not affect CTmin nor lethal SCP (=body freezing). Metabolomic profiling revealed the upregulation of some anaerobic metabolites and alterations in concentrations of citric acid cycle intermediates during and after chilling exposure. Hypoxia exacerbated the anaerobic metabolite responses. These results suggest that the chilling tolerance of T. leucotreta larvae is not oxygen limited, in keeping with the handful of other studies of tracheate arthropods that have investigated low temperature responses under altered oxygen levels. This study also presents clear evidence of some scope for anaerobic metabolism in T. leucotreta, which likely contributes to their ability to survive in necrotic fruit.
