Impact of dietary substitute with certain plant extracts on the development of royal jelly glands in honeybees workers

This study investigate the efficacy of two botanical extracts, Doum fruit (DE) and Mulberry leaves (MLE), as dietary supplements on the development of secretory glands in Apis mellifera workers. Honeybee workers were fed a pollen substitute and sugar syrup (1:1 w:w) supplemented with 1% DE (diet B) and 0.5% MLE (diet C). Morphometric analysis focused on the Hypopharyngeal Glands (HGs) and Mandibular Glands (MGs) across different worker ages. Chemical analysis of the extracts (GC-Mass) quantified protein, phenolic, and flavonoid content to establish a biological basis for the observed effects. MLE group demonstrated significantly superior gland development compared to the Doum extract, diet (A) without extract and syrup-only (diet D) control groups. The MLE group recorded the highest HGs acini area (0.034 mm2) and acini number (218.93 acinus10mm), alongside the largest MG area (0.82 mm2) and heaviest head weight (8.11 mg). Chemical profiling indicated that MLE possessed a substantially richer composition (5.0% protein; 36 phenolic/flavonoid compounds) than DE (1.9% protein; 18 compounds). The superiority chemical composition of Mulberry leaves extract may be the catalyst, along with the diet substitute, for the development of royal jelly glands compared to Doum fruit extract and other diets, with HGs peaking at 12 days and MGs peaking at 18 days of age in all treatments. In conclusion, dietary supplementation with Mulberry leaves extract is highly recommended for maximizing the functional morphology of royal jelly-producing glands in honeybee workers. This research highlights MLE's potential as a potent natural supplement to boost colony health and productivity.