Optimizing Fluctuating Low-Temperature Storage of the Predatory Mirid Tytthus chinensis and Its Physiological Responses to Cold Stress

Low-temperature storage (LTS) can extend the shelf life of natural enemies and improve deployment flexibility. This study evaluated the effects of temperature, food source, and insect stage on the survival of Tytthus chinensis during LTS, and further assessed the impacts of optimized storage conditions on adult longevity, predation, cryoprotectant accumulation, and enzyme activities. Under a fluctuating thermal regime (20 h at 10 ℃ followed by 4 h at 25 ℃) with 10% honey solution supplementation, female adult survival remained above 90% after 15 days of storage. This regime significantly prolonged longevity without significantly affecting predation capacity. Under the fluctuating thermal regime (20 h at 10 ℃ followed by 4 h at 25 ℃), female T. chinensis exhibited increases in glucose, trehalose, fructose, and glycerol contents by 67.3%, 100.9%, 45.6%, and 36.2%, respectively, accompanied by elevated lactate dehydrogenase (LDH) and superoxide dismutase (SOD) activities (27.6% and 51.2%), whereas total protein content and Na + -K + -ATPase activity decreased by 25.7% and 69.7%, respectively, compared with 25 ℃. In males, fructose and glycerol contents decreased by 14.46% and 50.0%, respectively, while total protein, catalase (CAT), and SOD activities increased by 30.9%, 17.6%, and 22.9%, respectively; Na + -K + -ATPase activity declined by 51.2%. These findings demonstrate that LTS has considerable potential for T. chinensis mass rearing, particularly for synchronizing mass production with field release demands. To prolong longevity while minimizing quality deterioration, adult T. chinensis should be stored under the fluctuating regime of 20 h at 10 ℃ and 4 h at 25 ℃ with supplementation of 10% honey solution.