Efficacy of volatile oil in onion flower nectar treated with some bio-stimulant extract materials on controlling some honey bee diseases in New Valley, Egypt

This study investigated the impact of volatile oils from onion flower nectar on honey bee colony health over two consecutive seasons (2023-2024). Six colonies were divided into a treatment group (pollinating onion flowers) and a control group. Colonies were monitored monthly for worker bee mortality and for diseases, including chalkbrood, stonebrood, Nosema, Varroa, and American foulbrood. Results demonstrated that the treatment groups exhibited a significant decline in bee mortality and a 61-74% reduction in chalkbrood incidence, while stonebrood was completely absent. Furthermore, treated colonies showed a complete clearance of Nosema, Varroa, and American foulbrood within weeks, maintaining a pathogen-free status. In stark contrast, control colonies experienced a significant increase in all disease parameters and mortality. Statistical analysis confirmed a 73% reduction in Nosema, a 79% reduction in Varroa, and a 58% reduction in mortality in onion-pollinated colonies, with all comparisons highly significant (p < 0.001). The study concludes that onion flower volatile oils possess strong bioactive properties, offering a potent, sustainable alternative to chemical treatments for enhancing bee health and suppressing disease.