Context-dependent effects of temperature on starvation resistance in Drosophila melanogaster: Mechanisms and ecological implications

Abstract

Temperature can modulate the responses of ectotherms to environmental stressors, such as food shortage. Temperature-mediated plasticity in starvation resistance can arise by changes in the amount of energy stored, the speed of energy expenditure, or the threshold energy reserves required for survival. However, few studies have investigated how temperature affects these physiological mechanisms underlying starvation resistance. In this study, we first examined the mechanistic basis of the temperature dependence of starvation resistance in Drosophila melanogaster. We then tested whether the effects of temperature on starvation resistance would depend on diet and developmental stage in this species. We found that exposure to high temperature during starvation significantly reduced the capacity of D. melanogaster to resist starvation. This warming-induced decrease in starvation resistance was mainly caused by faster depletion of body lipids and not by lower threshold lipid content for survival. D. melanogaster exposed to higher temperatures during feeding accumulated more body lipids and thus became more starvation resistant. Such positive effect of high feeding temperature on starvation resistance was pronounced when D. melanogaster consumed carbohydrate-rich diets. D. melanogaster raised as larvae at low temperature (18 °C) had a weaker starvation resistance at adult emergence compared to those raised at higher temperatures (23 and 28 °C). These results demonstrate that the effects of temperature on starvation responses are highly context-dependent in D. melanogaster.