Meeting Abstract
Insects exposed to low temperature stress may experience chill injury or death. Using fluctuating temperatures, in which insects receive a daily pulse of heat instead of constant low temperature stress has long been known to increase survival of insects in many life stages. The alfalfa leafcutting bee, Megachile rotundata, is a solitary, cavity-nesting bee that overwinters as a prepupa. Its survival of low temperature stress during overwintering is improved by a daily, one-hour pulse of heat. In addition, bees that have begun metamorphosis and are no longer in the protective state of diapause can be interrupted with low temperature stress to delay development. These interrupted bees also have improved survival when the low temperature stress is accompanied by a daily pulse of heat. Compared to constant low temperature stress, pupae that receive a daily warm pulse exhibit reversal of sub-lethal defects in adult wing morphology and flight performance. Bees exposed to fluctuating temperatures during pupal interruption also have better synchronization of adult emergence and increased reproduction compared to bees exposed to constant low temperature stress. Interestingly, these benefits exist even when the fluctuating temperatures are not ecologically relevant. The critical parameters of the fluctuating thermal regime that provide the beneficial effect (e.g., time spent above or below a thermal threshold, maximum or minimum temperature) are unclear. Understanding which parameters contribute to improved survival and fitness of these bees can help improve storage for commercially reared species and will help us to make better predictive models for how bee populations may respond to changing climates.
