Heat‐induced inhibition of hormone biosynthesis compromises fitness in the stored product pest Callosobruchus maculatus

BACKGROUND: Rising global temperatures increasingly threaten insect survival and development. Callosobruchus maculatus is a globally distributed stored-product pest that causes substantial economic losses to legume seeds, yet its physiological and molecular responses to heat stress remain poorly understood. Focusing on the primary damaging stage, we applied multi-omics to characterize heat stress in fourth-instar larvae, aiming to reveal systemic molecular changes under heat stress and identify potential targets for pest control. RESULTS: Heat stress differentially affected developmental stages, with eggs and larvae more sensitive than pupae. Sustained heat exposure reduced female fecundity even though it extended adult lifespan. Multi-omics analyses revealed that the insect hormone biosynthesis pathway was significantly down-regulated at both transcriptional and metabolic levels, leading to reduced juvenile hormone (JH) and 20-hydroxyecdysone (20E) titers. Hormone supplementation assays suggested that JH and 20E at appropriate concentrations significantly rescued the growth inhibition phenotype induced by heat stress. CONCLUSION: Our findings suggest that heat stress reprograms the molecular network of the insect hormone biosynthesis pathway, resulting in decreased JH and 20E titers in larvae and consequent developmental suppression in C. maculatus. This work provides a mechanistic foundation for exploring future management strategies against of C. maculatus targeting hormone signaling pathways.