Compensatory MAPK signaling coordinates hypoxia tolerance and trehalose metabolism in Tribolium castaneum

Tribolium castaneum is a devastating stored-grain pest globally, exhibiting remarkable tolerance to hypoxic environments, which severely compromises the efficacy of modified atmosphere treatments. Although the mitogen-activated protein kinase (MAPK) pathway is a central hub for eukaryotic stress responses, the molecular mechanisms underlying MAPK-mediated hypoxia adaptation in T. castaneum remain elusive. This study aimed to elucidate the response patterns of the MAPK pathway and its regulation of carbohydrate metabolism, providing a scientific basis for establishing targeted molecular intervention strategies.

Exposure to hypoxia (2% O₂) induced a significant time-dependent increase in mortality in T. castaneum; nonetheless, 42.4% of the initial adults survived after 7 days, confirming stable hypoxia adaptation. The key MAPK genes exhibited a temporally staged activation pattern. TcMAPKK6 and Tc-p38 were rapidly activated during the early phase of hypoxia (0.5-2 h), followed by sustained upregulation of TcERK (up to 3.1-fold) and TcJNK during the middle phase (3-6 h). A functional compensation mechanism between TcERK and Tc-p38 was identified: silencing either gene triggered compensatory upregulation of the other, maintaining downstream signal transduction. Knockdown of TcERK, Tc-p38 or TcJNK significantly increased mortality under 5% O₂, reaching 63.33% to 75.56%. This increased sensitivity was associated with disrupted carbohydrate homeostasis. TcERK and Tc-p38 knockdown reduced trehalose accumulation by up to 8.76 mg g^-1 and altered glycolytic enzyme activities, with TcERK mainly affecting hexokinase and pyruvate kinase (PK) and Tc-p38 affecting phosphofructokinase and PK. These results suggest that ERK and p38 contribute to the coordination of trehalose accumulation and glycolytic enzyme activity under hypoxic stress.

This study provides systematic evidence that T. castaneum mediates hypoxia adaptation through a synergistic network involving temporally staged activation, subfamily functional compensation, and metabolic reprogramming. These findings validate TcERK, Tc-p38, and TcJNK as potent molecular targets, providing a critical theoretical foundation for integrating modified atmosphere with RNA interference-based sensitization to achieve sustainable management of stored-grain pests. © 2026 Society of Chemical Industry.