Background and objective: Hypopharyngeal gland (HPG) of Apis mellifera L. honey bee workers secrete the main proteinaceous substances, the royal jelly which acts a vital role in brood care by young workers and thus colony growth. Many factors may affect the development and function of the hypopharyngeal gland and consequently their role within the beehive.
Materials and methods: Hyphaene thebaica fruit powder (500 g) was soaked in one litter of 70% ethanol for 3 days at room temperature, then filtered and concentrated to dryness with a rotary evaporator. Bioactive compounds and biological activity of doum ethanolic extract were characterized to measure the extent of safety. Samples of workers bee feeding with the extract concentrations (0.5 and 1%) at 6, 10 and 14 days were examined for head weight, body weight, soluble protein content, DNA fragmentation and hypopharyngeal glands histology, the data were analyzed using analysis of variance (ANOVA), Tukey's least significant difference.
Results: Ethanolic doum extract contains flavonoids (45.62 mg g-1) and phenolic (27.24 mg g-1) compounds, also possess antioxidant (147 μg mL-1), anti-inflammatory (119.8 μg mL-1) and antimicrobial activities. There was an elevation in soluble protein content and no DNA damage in the honey bee worker's genome after fourteen days of feeding. The histological studies exhibited no deformation in the structure of gland acini and an increase in gland size was detected.
Conclusion: Ethanolic doum extract in the bee diet has a role in HPG enhancement. Studies on its safety profile and biological activities make it a good choice to attenuate honey bee diseases inside bee colonies.
Keywords: Apis mellifera; DNA fragmentation; Hyphaene thebaica; antimicrobial activity; diet supplement; histology of hypopharyngeal glands; total soluble protein.