Insects rarely experience heat, oxygen limitation, water loss, and immune challenge as biologically independent perturbations. Yet these stressors are often interpreted through separate pathway literatures, encouraging a one-stressor–one-response view that obscures shared demands on redox control, ATP production, substrate allocation, membrane and barrier integrity, proteostasis, repair, and endocrine-metabolic regulation. This article develops an molecular-systems model in which the four stress domains remain distinct at exposure and proximal-sensing levels but can converge on shared physiological nodes. Evidence from insect models supports specific intersections, including thermal-history effects on later hypoxia sensitivity, heat–desiccation coupling through cuticular function, dehydration-dependent modification of infection outcome, and heatwave-induced changes in immune performance. However, no current evidence establishes a universal four-stressor master pathway. The model therefore separates directly demonstrated links from cross-study synthesis and proposed network relationships. It further distinguishes molecular activation from protection, acclimatory state from evolutionary adaptation, and laboratory pathway effects from field-generalizable outcomes. The resulting architecture predicts that compound-stress phenotype should depend not only on stressor identity and intensity, but also on tissue, life stage, taxon, exposure order, recovery opportunity, and pre-existing energetic and redox state. This framework provides testable organizing principles for experiments that manipulate stress combinations while measuring shared nodes and downstream damage rather than treating each stress response as an isolated program.
