Effect of diapause duration on thermal tolerance in the cabbage beetle Colaphellus bowringi Baly

Insect diapause duration has a profound impact on post-diapause fitness and physiological performance. This study explores how diapause duration (ranging from 0.5 to 2 years) affects heat tolerance in both adult cabbage beetles, Colaphellus bowringi Baly, and their offspring. The investigation integrates survival assays, LT₅₀ analysis, and respiratory metabolism. Results indicate that shorter diapause durations significantly enhance heat tolerance in adult beetles, demonstrating a clear negative correlation between diapause duration and thermal resilience. Specifically, adult beetles undergoing 0.5 years of diapause exhibited an LT₅₀ of 36.79 °C, whereas those with 2 years of diapause showed an LT₅₀ of 29.58 °C. However, no significant differences in thermal tolerance were observed among offspring across all tested life stages (eggs, larvae, pupae, and adults), regardless of parental diapause duration. Larval respiratory responses to acute heat stress displayed a consistent thermal performance curve peaking at 39 °C and declining sharply at higher temperatures. These findings highlight a trade-off between diapause duration and heat tolerance, suggesting a potential role for metabolic costs and stress defense mechanisms. These findings highlight the importance of diapause duration in shaping thermal tolerance and suggest complex interactions between dormancy and stress resilience. Future research should aim to uncover the molecular mechanisms involved and examine the broader ecological implications of diapause duration on population dynamics under changing climatic conditions.