Optimizing cold storage for diapause termination and post-diapause performance in the green lacewing Chrysopa formosa Brauer (Neuroptera: Chrysopidae)

Abstract Background Diapause is an adaptative strategy that enables insects to survive unfavorable environmental conditions, and its regulation is critical for large-scale production and storage of natural enemies used in biological control. The green lacewing Chrysopa formosa Brauer (Neuroptera: Chrysopidae) is an important generalist predator with high potential for pest management, yet its practical application requires effective diapause manipulation to ensure continuous supply of high-quality individuals. In this study, we systematically evaluated the effects of different cold storage durations (60–240 days) at 5 °C on diapause termination, post-diapause development and reproduction of C. formosa . Results Cold storage duration significantly affected diapause termination and subsequent performance. Storage for 100–120 days effectively terminated diapause, with pupation rates exceeding 89%, comparable to the non-diapause control. Short-term chilling (60 days) resulted in a lower termination rate (75%), whereas prolonged storage (240 days) caused a significant decline in pupation (< 60%) and vitality. The time to pupation and adult emergence decreased and became more synchronized with increasing storage duration. Adult emergence exceeded 65% across the 100–240 day treatments, but longevity declined significantly when storage exceeded 180 days. Moderate storage (~ 120 days) optimized reproductive performance, producing a shorter pre-oviposition period, prolonged oviposition duration, and higher fecundity. However, egg viability decreased markedly after 180 days (< 60%) but remained comparable to controls in the 120-day treatment (73.3%). Conclusion Overall, 100–120 days of cold storage achieved a good balance between effective diapause termination and post-diapause fitness in C. formosa . However, extended chilling (> 180 days) impaired adult performance, indicating a practical storage limit for large-scale production. These results establish a flexible diapause management window for C. formosa , facilitating its long-term preservation and year-round utilization in augmentative biological control programs.