Silencing the Circadian Clock Genes Cycle and Clock Disrupts Reproductive–Metabolic Homeostasis but Does Not Induce Reproductive Diapause in Arma chinensis

The circadian clock is a conserved timekeeping mechanism that enables organisms to anicipate and adapt to daily environmental cycles. While its role in photoperiodic diapause has been documented, its fundamental function in maintaining reproductive and metabolic homeostasis under favorable conditions remains less explored, especially in biological control agents. This study investigates the functional roles of the core circadian clock genes <i>Cycle</i> (<i>AcCyc</i>) and <i>Clock</i> (<i>AcClk</i>) in the predatory bug <i>Arma chinensis</i>, focusing on their regulation of reproduction and metabolism under non-diapause conditions. We characterized these genes and analyzed their spatiotemporal expression under diapause and non-diapause conditions. Using RNA interference, we knocked down <i>AcCyc</i> and <i>AcClk</i> in non-diapausing females and evaluated phenotypic impacts on ovarian development, fecundity, and energy reserves. qPCR analyses delineated downstream effects on juvenile hormone (JH) signaling. Results showed that diapause altered <i>AcCyc</i> and <i>AcClk</i> expression rhythms. Their knockdown severely impaired reproduction, reducing ovarian size, vitellogenin expression, and egg production, while concurrently decreasing triglyceride levels indicating disrupted energy homeostasis. Mechanistically, gene silencing downregulated key JH pathway components, <i>Methoprene-tolerant</i> (<i>Met</i>) and <i>Krueppel homolog 1</i> (<i>Kr-h1</i>). We conclude that <i>AcCyc</i> and <i>AcClk</i> are essential maintainers of reproductive-metabolic homeostasis, not merely diapause regulators. This reframes the clock's role from a seasonal timekeeper to a central hub for daily physiological coordination, offering new insights for improving biocontrol agent production.