Nutritional phenotype underlines the performance trade-offs of Drosophila suzukii on different fruit diets

Abstract

Animals confined to different dietary conditions often exhibit distinct, sometimes contrasting, nutritional phenotypes and performance outcomes. This is especially true for many oviparous insects whose developmental diets can vary depending on the mother's egg-laying site selection. Much research on the relationship between preference and performance in insects has focused on larval success, which overlooks the complexities of dietary effects on diverse performance parameters across life stages and potential trade-offs between those parameters. Furthermore, the connection between diet-induced nutritional phenotype and performance trade-offs is not well understood. Here, using Drosophila suzukii, we quantify multiple performance indices of larvae and adults reared on five host fruits of different protein-to-sugar ratios (P:S) which have previously been shown to differ in attractiveness to fly foraging and oviposition. Our results demonstrate robust diet-specific performance trade-offs, with fly fecundity, larval development time, pupal size, and adult weight superior in flies reared on the high P:S raspberry diet, in contrast to the low P:S grape diet; but the reverse was found in terms of adult starvation resistance. Notably, the contrasting performance trade-offs are readily explained by the fly nutritional phenotype, reflected in the protein and energy (glucose and lipid) contents of flies reared on the two fruits. Together, our results provide experimental evidence for metabolic plasticity of D. suzukii reared on different fruits and the possibility of using adult nutritional phenotype as a marker for diet and performance outcomes.

Keywords: Drosophila; diet; nutritional ecology; oviposition; protein leverage; starvation resistance; trade-offs.

Figure 1

Reproduction and development of D. suzukii on five different host fruits. (A) Number of viable offspring produced per female. (B) Developmental time from eggs to adults. (C) Pupal length. (D) Representative images of pupae raised from the different fruits. * P< 0.05, ** P < 0.01, *** P < 0.001, **** P < 0.0001 (One-way ANOVA, Tukey's HSD). P values were adjusted by Bonferroni.

Figure 2

Survival rate of D. suzukii adult females (F1) raised on different fruit diets to starvation. N represents the number of vials with each containing 10-20 flies. Different letters indicate significant differences at P < 0.05 (log-rank test; See supplementary materials for statistical details).

Figure 3

Foraging of D. suzukii female flies toward P:S=1:22 and P:S=1:4 diets made of sucrose, yeast, and casein. (A) The heatmaps and (B) boxplots represent the cumulative time spent in the P:S=1:4 or P:S=1:22 zone. Each arena containing eight female flies was tracked by one camera for 6 hours. Three cameras were set up in the experimental run. Wilcoxon rank-sum test was performed. P values were adjusted by Bonferroni. *P < 0.05. ns stands for non-significant (P > 0.05).

Figure 4

Nutritional phenotypes of adult female D. suzukii on the raspberry and grape diets. (A-D) Comparisons of fresh weight, protein, glucose, and triglyceride levels. (E) Confocal images of fat bodies stained with BODIPY and DAPI to show lipid droplets and nuclei, respectively. (F) Lipid droplet size quantified by imageJ based on the representative confocal images. Each dot represents a single lipid droplet. P values were Bonferroni-adjusted *P< 0.05, ** P < 0.01, *** P < 0.001, **** P < 0.0001.