Evaluating the Influence of Different Artificial Diets on Apis mellifera L. Using Health Biomarkers and Performance Metrics

The diet of <i>Apis mellifera</i> L. is a crucial factor for managing its colonies particularly during dearth periods. Numerous diets have been developed; however, their global implementation faces challenges due to diverse climatic conditions and some other factors. To address this issue, three previously evaluated diets (selected from seven) were tested to assess their effects on <i>A. mellifera</i> using key health biomarkers (immune function, stress response) and performance metrics (foraging activity, honey quality, and social interactions). The experiment was conducted using 12 colonies, including three replications, in The Islamia University of Bahawalpur, Pakistan, from June to September 2023. The results revealed that all the tested parameters were significantly affected by diets. Highest phenol-oxidase activity was recorded in T1 (28.7 U/mg). Heat shock protein (HSP) bands showed that T1 had the fewest (Hsp70), while T0 had more bands (Hsp40, Hsp60, and Hsp70), indicating stress differences. In foraging activity, average number of outgoing bees were highest in T1 (81.8) and lowest in T0 (31.2) and similar trend was followed for returning bees, i.e., T1 (81.8) and T0 (31.2). For pollen-carrying bees, the highest bees were counted in T1 (34.9), and the lowest in T0 (4.10). Honey quality was also significantly affected by diets, pH was highest in T1 (3.85), while moisture was highest in T0 (19.44%). Diastase activity, ash content, and electrical conductivity were best in T1 (13.74 units/g, 0.17%, 0.94 mS/cm, respectively). Mineral content was highest in T1 (406.54 mg/kg), and fructose content also peaked in T1 (396.21 mg/kg). Antioxidant contents, total phenolic content, flavonoid content, and ORAC value were highest in T1 (60.50 mg GAE/100 g, 44.41 mg QE/100 g, 10,237.30 µmol TE/g), while T0 consistently showed the lowest values across all parameters. In social interaction experiments, trophallaxis events were most frequent in T1 (7.38), and T1 also exhibited the longest trophallaxis time (5.51 s). The number of bees per trophallaxis event and antennation frequency followed a similar trend, with the highest recorded in T1 (5.16 bees/event, 10.1 antennation frequency) and the lowest in T0 (2.94 bees/event, 4.18 antennation frequency). Therefore, diet-1 (Watermelon juice 20 mL + Fenugreek powder 2 g + Chickpea flour 20 g + Lupin flour 20 g + Mung bean flour 20 g + Yeast 10 g + Powdered sugar 40 g + vegetable oil 10 mL) is recommended as a suitable substitute for managing <i>A. mellifera</i> colonies during dearth periods.