Comparative effects of antibiotics and bee venom on toxicity and immune-related gene expression in honey bee ( <i>Apis mellifera L</i> ) larvae reared <i>in vitro</i>

Honey bees ( Apis mellifera ) play a critical role in pollination and global food security, yet their populations are increasingly threatened by pathogens, pesticides, and management practices. Understanding how commonly used apicultural treatments affect larval development and immunity is therefore essential. In vitro larval rearing provides a controlled environment to investigate the physiological and molecular responses of honey bee larvae to such stressors. In this study, the toxicological effects of oxytetracycline (antibiotic) and bee venom were compared by determining LC₅₀ values and assessing the expression of immune-related genes. LC₅₀ analysis revealed that bee venom exhibited higher toxicity than the antibiotic, with values ranging from 0.015 to 1.080 mg/L over six days, whereas antibiotic treatments showed LC₅₀ values between 1.617 and 2.663 mg/L. The LC 50 value represents the concentration required to cause 50% mortality, with lower values indicating higher toxicity. Gene expression profiling (RT-qPCR) demonstrated that antibiotic exposure significantly downregulated several immune-associated genes, including Loc406090 (−9.67 fold), Loc406102 (−4.14 fold), and Loc406109 (−3.51 fold) ( P &lt;0.05), compared to controls. In contrast, bee venom treatment led to both up- and down-regulation patterns, with a notable downregulation of Loc406103 and Loc413113 ( P &lt;0.05). These findings suggest that although bee venom is more acutely toxic at higher concentrations, it modulates immune gene expression differently from antibiotics, potentially enhancing certain immune pathways. The results highlight the dual impact of antibiotics and bee venom on honey bee health and underscore the importance of further research into bee products as potential alternatives to antibiotics in apiculture. GRAPHICAL ABSTRACT