ABSTRACT Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), is an important natural enemy of aphids, thrips, whiteflies, scale insects, psyllids, and mites. The successful use of this predator in biological control programs requires knowledge of its biology, mass rearing, and cold storage. In this study, we aimed to investigate the effects of different diets, including Agonoscena pistaciae, Aphis nerii (both nymphs and adults), and Ephestia kuehniella (eggs), along with three supplementary compounds (glycerol, trehalose, and proline), on the cold hardiness, lower lethal temperatures (LLT), critical thermal minimum (CTmin), and supercooling point (SCP) of H. variegata. We also explored the potential for rapid cold hardening to enhance the predator's cold tolerance. Our results indicate that both diets and cold acclimation have significant effects on the supercooling point depression and cold tolerance enhancement. The diet of E. kuehniella eggs showed the highest survival rate (89% at −2°C/24 h) and the lowest supercooling point (−18.3 °C), making it the best option based on these two criteria. However, the addition of potential cryoprotectants did not significantly affect the supercooling capacity of the predator. The diet of E. kuehniella eggs also had the lowest CTmin (−1.71 °C) and lower lethal temperatures (LT50 = −4.0 °C), confirming its suitability as the best diet for H. variegata. Exposing the predator to rapid cold hardening can further enhance its cold tolerance. Our findings have important implications for the mass rearing and cold storage of H. variegata and its potential use in biological control programs.
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