The Effects of Cold Acclimation on Cold Tolerance and Growth and Reproduction of Plodia interpunctella

Abstract

Plodia interpunctella is a globally significant pest of stored grains, posing a major threat to food safety. To explore its cold-adaptation mechanisms, this study evaluated the physiological and developmental responses of different life stages following short-term cold acclimation at 4 °C. Results showed that cold acclimation significantly reduced the supercooling points (SCPs) of larvae and pupae, with the greatest reduction observed in the second instar larvae. Antioxidant enzyme assays revealed marked increases in the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), indicating enhanced oxidative stress resistance. Developmental durations were significantly shortened at lower temperatures in acclimated individuals, and fecundity was notably increased at 24 °C, although no significant changes were observed at higher temperatures. These findings suggest that cold acclimation improves the cold tolerance and reproductive performance of P. interpunctella under low-temperature conditions, offering insights into insect adaptability and providing theoretical support for the development of low-temperature-based pest management strategies in stored grain systems.

Keywords: Plodia interpunctella; cold acclimation; cold tolerance; stored grain pest; supercooling point.

Figure 1

Morphological changes in body pigmentation of the second and fourth instars P. interpunctella larvae following cold acclimation treatment. Uppercase letters in the figure represent larvae before cold acclimation, and lowercase letters denote larvae after cold acclimation.

Figure 2

Supercooling point of P. interpunctella at different developmental stages under cold-acclimated and non-acclimated conditions. Supercooling point of P. interpunctella at different developmental stages under cold-acclimated and non-acclimated conditions. Data represent mean ± standard error. Different uppercase letters indicate significant differences in supercooling point among developmental stages before cold acclimation, while different lowercase letters indicate significant differences after cold acclimation. The asterisk denotes a statistically significant difference in supercooling point (SCP) between cold-acclimated and control groups of P. interpunctella. ns means no significant difference, * means p < 0.05, and *** means p < 0.001.

Figure 3

Changes in the activities of SOD (A), POD (B), and CAT (C) in P. interpunctella under cold-acclimated and non-acclimated conditions. SOD: superoxide dismutase, CAT: catalase, POD: peroxidase. Data represent mean ± SEM. Asterisks indicate significant differences between control and treatments. *** means p < 0.001.

Figure 4

Developmental and survival period of P. interpunctella egg (A), larva (B), pupa (C), and adult (D) under cold-acclimated and non-acclimated conditions. Under three temperature regimes (24 °C, 28 °C, and 32 °C). Data represent mean ± SEM. Asterisks indicate significant differences between control and treatments. ns means no significant difference, and * means p < 0.05.

Figure 5

Mean egg production of P. interpunctella females under cold-acclimated and non-acclimated conditions at different temperatures. Data represent mean ± SEM. Asterisks indicate significant differences between control and treatments. ns means no significant difference, and ** means p < 0.01.