From nurse bee to queen egg: RNA-seq analysis of Apis mellifera eggs shows dietary protein-dependent gene regulation

Honeybees, Apis mellifera, play a vital role as pollinators in global agricultural ecosystems. Nutrition, particularly dietary protein content, profoundly impacts honeybee health and reproduction. Yet, the molecular mechanisms connecting diet composition and gene expression in honeybee eggs remain underexplored. In this study, we investigate the intricate relationship between diet, gene expression, and honeybee egg development. Using RNA-seq analysis, we explore the effects of different protein-to-carbohydrate (P: C) ratios in honeybee diets on differential gene expression in the eggs laid by the queen and potential associated molecular responses. Our research identifies 1007 differentially expressed genes (DEGs) across various dietary conditions, highlighting the pivotal role of nutritional composition in shaping gene expression during egg development.Cluster analysis revealed two DEG profiles corresponding to low protein diets (LPD) and high protein diets (HPD). LPD conditions upregulate genes linked to protein catabolism, autophagy, and ubiquitin-mediated proteolysis, indicating potential cellular responses to nutritional stress. Conversely, HPD conditions upregulate genes related to RNA processing, spliceosome activity, and the MAPK signalling pathway, suggesting normal cellular development.Notably, the Hippo signalling pathway exhibits distinct gene regulation patterns under LPD and HPD conditions, potentially influencing cellular growth and differentiation in response to nutrient availability.Our findings underscore the critical role of nutrition in honeybee health and reproduction, providing insights into optimizing honeybee diets for colony health and resilience. As honeybee populations confront challenges from changing environmental conditions and resource availability, understanding these molecular responses is crucial for their effective management and conservation as essential pollinators. This study establishes a foundation for further investigations into the functional consequences of these molecular responses at the individual level and their broader implications for honeybee colony development and health.