Flexibility of metabolic rate to temperature coincides with diapause strategy

During dormancy, insects operate on a fixed energy budget and suppress
metabolic rate to extend the duration that their energy reserves last.
Extending energy stores to last an entire winter can pose a significant
challenge, as some habitats have winters that last most of the year. There
are cases where insects enter dormancy in mid-summer and remain until the
following spring. This multi-season dormancy should pose an even more
significant energetic challenge, since these insects must conserve energy
during winter, as well as the warmest period of summer. We compared
metabolic rate-temperature curves of two related species of Pierid
butterflies: Pieris napi, which is dormant through winter, and Anthocharis
cardamines, which exhibits a multi-season dormancy. This comparison was
conducted at several time points under 18°C and 2°C acclimation
conditions. We found that A. cardamines can maintain considerable
metabolic suppression when acclimated to high temperatures, which is only
maintained until they are exposed to low temperatures. Overall P. napi
exhibits much lower levels of metabolic plasticity. Metabolic suppression
exhibited in A. cardamines is enough to prevent increased rates of mass
loss at high temperatures. Together, this provides evidence that both
environment and life history timing of dormancy can shape metabolic
plasticity.