Insect life-history responses to nutrition are often described as consequences of energetic or substrate limitation: growth slows when resources decline, reproduction contracts when nutrient supply is inadequate, and survival trade-offs emerge when allocation becomes constrained. This interpretation is necessary but incomplete. Nutrients also act as regulatory information, while juvenile hormone, ecdysteroids, insulin/insulin-like growth factor signaling, target of rapamycin, AMP-activated protein kinase, neuropeptides, and tissue-specific endocrine responses determine how nutritional information is converted into developmental or reproductive action. This article develops a molecular-physiological model in which insect life-history decisions depend on the joint configuration of nutrient identity and availability, endocrine state, developmental or reproductive state, and tissue-specific signal responsiveness. Evidence from Drosophila, mosquitoes, Bombyx, Manduca, and other insects indicates that similar nutritional inputs can yield different outcomes across stages, sexes, genotypes, and taxa, and that hormonal state can itself alter nutrient acquisition, metabolic processing, and pathway sensitivity. The proposed model therefore treats nutrition as a state-dependent signal rather than a scalar energetic input. It generates testable predictions about when identical nutritional environments should produce divergent life-history outputs and identifies the experimental boundaries required to distinguish causal signaling from correlated physiological state.
