The effect of dietary restriction on longevity, fecundity, and antioxidant responses in the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

- Dietary restriction extends lifespan in Bactrocera dorsalis.
- Constant and intermittent DR feeding regimes affected lifespan similarly.
- Carbohydrate-enriched diet is important for lifespan-extension by DR.
- SOD and GST activities responded sensitively to diets with different yeast levels.
- Antioxidant enzymes are correlated with lifespan in starvation and DR treatments.

Recent studies in fruit flies have imposed dietary restriction (DR) by diluting yeast and have reported increased lifespan as the yeast-to-sugar ratio decreased. In this study, the effects of DR on the lifespan of Bactrocera dorsalis were investigated using constant-feeding diets with different yeast:sugar ratios and an intermittent-feeding diet in which flies ate every sixth day. Antioxidant enzyme activities and the malondialdehyde concentration were also measured in virgin females under constant-feeding DR protocols to investigate their relationships with lifespan. The results showed that B. dorsalis lifespan was significantly extended by DR, and carbohydrate-enriched diet may be important for lifespan-extension. Female flies lived significantly longer than males at all dietary levels under both feeding regimes, indicating no interaction between diet and sex in determining lifespan. Antioxidant enzyme activities increased with the amount of yeast increased in the diets (0-4.76%) between starvation and DR treatments, indicating that the antioxidants may have influences in determining lifespan in B. dorsalis under starvation and DR treatments. However, antioxidants cannot keep up with increased oxidative damage induced by the high yeast diet (25%). These results revealed that the extension of lifespan by DR is evolutionarily conserved in B. dorsalis and that yeast:sugar ratios significantly modulate lifespan in this species.