GENE EXPRESSION AND ENZYMATIC REGULATION OF HONEY PRODUCTION IN HONEY BEES UNDER THERMAL AND PESTICIDE STRESS: A REVIEW

Abstract

Honey production in Apis mellifera is an actively regulated physiological process centered on the hypopharyngeal and salivary glands, driven by enzymes including invertase and glucose oxidase whose expression is tightly coordinated with worker developmental stage, behavioral caste, and hormonal signaling. This review synthesizes current molecular and enzymatic understanding of honey production, then examines how thermal and pesticide stress disrupt these pathways individually and, where evidence permits, in combination. Thermal stress alters gland protein synthesis and metabolic gene expression, while sublethal pesticide exposure downregulates key honey-production genes while activating detoxification pathways, suggesting a physiological trade-off. Limited but consistent evidence indicates these stressors interact synergistically rather than additively. The review identifies three priority gaps: the near-absence of gland-specific (as opposed to whole-body) combined-stressor studies, the need for CRISPR-based functional validation of candidate genes, and limited comparative data between Apis mellifera and Apis cerana. Closing these gaps would extend current single-stressor, whole-body findings toward a mechanistic, gland-level understanding directly relevant to colony health and honey yield under increasing environmental pressure.