Temperature can modulate how insects respond to environmental stressors, such as starvation. In this study, we examine whether and how the effects of temperature on starvation resistance depend on nutritional condition and developmental stages in Drosophila melanogaster. Starvation resistance decreased as the temperature exposed during starvation rose from 18 to 28 ̊C, which was mainly caused by warming-induced increase in energy expenditure. When exposed to warm temperatures during feeding, D. melanogaster accumulated more energy reserves and thus become more starvation resistant. The temperature experienced during the larval stage also had a significant effect on starvation resistance at adult stages, with those larvae raised at cold temperatures developing into adult phenotypes with reduced resistance to starvation. This study suggests that the effects of temperature on starvation resistance are highly complex and context dependent in D. melanogaster.

Temperature can affect the ability of insects to tolerate prolonged period of food deprivation through altering the amountof energy storage, the speed of energy expenditure, or the threshold energy storage for survival. In this study, we examinedthe mechanistic basis of the temperature-dependence of starvation resistance in Drosophila melanogaster. Starvation resistancedecreased as the temperature experienced during starvation rose from 18 to 28 ̊C. This warming-mediated decrease instarvation resistance was due to accelerated energy expenditure. However, the threshold energy storage for survival wasnot affected by starvation temperature. Exposure to warm temperatures during feeding led D. melanogaster to accumulatemore energy reserves and thus to become more starvation resistant. This study highlights the important role played bytemperature in shaping the phenotypic responses of insects to starvation.

Recent studies have shown that mating can alter starvation resistance in female D. melanogaster, but little is known about the behavioral and physiological mechanisms underlying such mating-mediated changes in starvation resistance. In the present study, we first investigated whether the effect of mating on starvation resistance is sex-specific in D. melanogaster. As indicated by a significant sex × mating status interaction, mating increased starvation resistance in females but not in males. In female D. melanogaster, post-mating increase in starvation resistance was mainly attributed to increases in food intake and in the level of lipid storage relative to lean body weight. We then performed quantitative genetic analysis to estimate the proportion of the total phenotypic variance attributable to genetic differences (i.e., heritability) for starvation resistance in mated male and female D. melanogaster. The narrow-sense heritability (h2) of starvation resistance was 0.235 and 0.155 for males and females, respectively. Mated females were generally more resistant to starvation than males, but the degree of such sexual dimorphism varied substantially among genotypes, as indicated by a significant sex × genotype interaction for starvation resistance. Cross-sex genetic correlation was greater than 0 but less than l for starvation resistance, implying that the genetic architecture of this trait was partially shared between the two sexes. For both sexes, starvation resistance was positively correlated with longevity and lipid storage at genetic level. The present study suggests that sex differences in starvation resistance depend on mating status and have a genetic basis in D. melanogaster.

Mating elicits a dramatic changes in physiology, behavior, and life-history traits in insects, but little is known about the relationship between mating and the capacity of insects to resist environmental stressors. Starvation is one of the most ubiquitous forms of environmental stress faced by all insects under natural conditions. Previous studies using Drosophila melanogaster flies has shown that mated females lived longer under starvation than did virgin females, but the mechanistic basis for such post-mating increase in starvation resistance remains largely unexplored. The objective of this study was to investigate the behavioral and physiological mechanisms of mating-induced alteration in starvation resistance and its heritable genetic variations in D. melanogaster. In the first experiment (Experiment 1), we compared starvation resistance (measured as starving time before death), body compositions, and food intake between mated and unmated flies of both sexes using a large outbred population. In the second experiment (Experiment 2), starvation resistance and body composition were quantified for mated male and female flies derived from each of 19 highly inbred genetic lines. Results from Experiment 1 showed that mated females were better able to resist starvation than virgin females and males because they ate more and thus laid down more fats in their body. Results from Experiment 2 revealed a significant heritable genetic variation in starvation resistance and its correlated body composition parameters for both sexes. Overall, females had a higher starvation resistance than males, but the magnitude of such intersexual difference varied among genetic lines, as suggested by a significant sex-by-line interaction. Cross-sex genetic correlations were highly significant and positive for starvation resistance, indicating that the genetic factors controlling the starvation resistance in D. melanogaster are shared between the two sexes.

Starvation resistance is an important fitness trait that is controlled by both environmental and heritable factors. The main objective of this study is to explore the genotype-by-nutrient interactions for starvation resistance and its correlating physiological traits in Drosophila melanogaster. In this study, we conducted a split-family quantitative genetic experiment, in which female adults of Drosophila from 19 isofemale genetic lines were allowed to ingest one of two synthetic diets that differed in protein-to-carbohydrate ratio (P:C = 4:1 or 1:16 with the P+C concentration of 120 g L-1) before they were assayed for starvation time and lipid storage. In all genetic lines, Drosophila flies that had fed carbohydrate-rich diet (P:C=1:16) resisted starvation better and stored more lipids than did those that had fed protein-rich diet (4:1). Importantly, the extent to which both starvation resistance and lipid reserves were affected by dietary P:C ratio varied greatly among different genetic lines of Drosophila, as indicated by significant genotypeby-nutrient interactions for these two traits. When the patterns of the bivariate reaction norm for body lipid and starvation resistance were compared across the genotypes, we found strong evidence for genetic variations in the pattern of energy storage and usage associated with maintaining survival under starvation in Drosophila.

Food limitation is the most common environmental challenge faced by animals and the capacity of animals to survive prolonged periods of starvation is linked to their diet and nutritional status. The objective of this study is to investigate the effects of nutrition on starvation resistance in Drosophila melanogaster. Experimental flies were given ad libitum access to artificial diets differing in concentrations and ratios of protein and carbohydrate for 5 days before they were assayed for starvation time, body composition and life-history parameters. Starvation resistance in Drosophila was greatly influenced by the dietary protein:carbohydrate (P:C) ratio, but neither by the caloric content of the diet nor by dietary carbohydrate alone. Starvation resistance was strongest at the lowest P:C ratio and declined with rising P:C ratio. While starving, Drosophila underwent a dramatic transition in the utilization of physiological fuels, switching from the early phase characterized by preferential consumption of non-lipid substrates to the next phase in which they began to mobilize lipids as fuels for enduring starvation. Our results highlight the importance of nutrition as a key factor determining starvation responses of Drosophila.