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.