Cold storage of Aphidoletes aphidimyza can extend offspring larval development period and improve its predation ability

Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) is widely used in aphid biological control, and low-temperature storage helps expand its population. Nonetheless, low-temperature effects on A. aphidimyza are unknown. A. aphidimyza pupae were exposed to three cold storage methods lasting 10, 20, and 30 days, respectively: storing at 7 °C for 4 h then 5 °C for 20 h (T1); storing at 9 °C for 4 h then 5 °C for 20 h (T2); and storing at 5 °C for 24 h (T3). The emergence rate under variable low-temperature storage (T1: 81.98%; T2: 81.28%) was significantly higher than that under constant low-temperature storage (T3: 74.98%). Additionally, the emergence rate decreased markedly with prolonged refrigeration time. Egg production at all three refrigeration temperatures declined significantly compared to the control treatment. It is noteworthy that low-temperature storage can significantly prolong the development time of offspring larvae without affecting the overall developmental period of the offspring. After comparing the content of cold-resistant substances in pupae under different low-temperature storage, the total sugar, glycerol, and trehalose increased with an extended storage time. The lifetime feeding capacity of A. aphidimyza offspring larvae on Myzus persicae (Sulzer) improved after cold storage. The functional response curve was aligned with the Holling Ⅱ model. Compared to the control treatment, both T1, T2, and T3 improved the search ability of 3rd-instar larvae in the offspring after 20 and 30 days of refrigeration. Our study indicated that cold storage of A. aphidimyza can extend offspring larval development period and improve its predation ability.