Habitual dietary alteration reduces egg quality and quantity by affecting ovarian development and nutrient accumulation in Bombyx mori (Lepidoptera: Bombycidae).

Substituting fresh mulberry leaves with artificial (compound) diets is a growing trend in industrialized sericulture. However, breeder silkworms (Bombyx mori, Lepidoptera: Bombycidae) reared on artificial diets (ADs) throughout their larval stage exhibit severely impaired reproductive fitness, which is a major bottleneck and the mechanism responsible remains unclear. In this study, we demonstrated that rearing on AD inhibited 20-hydroxyecdysone (20E) signaling during the pupal stage, thereby interfering with the synthesis and transport of vitellogenin and 30Kc19 in the fat body. This perturbation caused the abnormal accumulation of 30Kc19 and egg-specific protein in the ovary, as well as severe glycogen deficiency, which ultimately suppressed oogenesis, reduced the egg quantity and quality, and triggered transgenerational declines in offspring viability and reproductive performance. Exogenous 20E supplementation effectively restored the female reproductive capacity. Thus, we elucidated the mechanism responsible for the reproductive decline of silkworms reared on AD, providing a theoretical foundation for intervention strategies.