This study explores the molecular mechanisms underlying diapause in the parasitoid wasp Telenomus remus (Nixon) (Hymenoptera: Platygastridae), a critical egg parasitoid for the biological control of the invasive pest Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). While effective in pest management, T. remus faces limitations in large-scale applications due to its short lifespan and low viability under storage conditions. Diapause, a state of developmental arrest, was successfully induced in T. remus using photoperiod manipulation (0L:24D), allowing for extended survival and improved storage potential. Transcriptome sequencing identified 2642 differentially expressed genes, with 617 involved in 284 enriched pathways, including calcium signaling and phototransduction. The study found that the expression levels of CBP1 and CBP2, genes encoding calcium-binding proteins, were significantly downregulated during diapause. As key regulators in calcium ion-mediated signal transduction pathways, the downregulation of CBP1 and CBP2 may lead to the suppression of intracellular calcium signaling, thereby affecting light signal transduction and energy metabolism regulation. This suggests that during diapause, insects may reduce calcium signaling activity to suppress physiological functions, maintain a low metabolic state, and decrease sensitivity to environmental stimuli. Additionally, ARR genes still exhibited differential expression, further supporting their potential role in phototransduction and diapause regulation.