Slow or stepped rewarming after acute low-temperature exposure does not improve survival ofDrosophila melanogasterlarvae

Abstract

AbstractWe tested the hypothesis that slow rewarming would improve the ability ofDrosophila melanogasterMeigen (Diptera: Drosophilidae) larvae to survive acute low-temperature exposure. Four larval stages (1st, 2nd, and 3rd instars, including wandering-stage 3rd instars) of four wild-type strains were exposed to –7 °C for periods of time expected to result in 90% mortality. Larvae were then directly transferred to their rearing temperature (21 °C) or returned to this temperature either in a stepwise fashion (pausing at 0 and 15 °C) or by slow warming at 1 or 0.1 °C/min. We observed a reduced rapid cold-hardening effect and no general increase in survival of acute chilling in larvae rewarmed in a stepwise or slow fashion, and we hypothesize that slow rewarming may result in accumulation of chill injuries.