Synchrony of sunflower bloom and bee activity: A Diurnal study on Apis cerana indica foraging efficiency

Abstract

The foraging dynamics of Apis cerana indica were evaluated on sunflower (Helianthus annuus) across 50% and 100% flowering stages to assess variations in trip frequency, duration, and pollen collection. Results revealed a significant increase in the number of foraging trips during full bloom, with peak activity recorded between 10:00-14:00 h, where trip frequency reached up to 1.66 trips per 10 minutes compared to 1.16 trips at 50% flowering. Enhanced floral abundance at 100% flowering also improved foraging efficiency, as evidenced by shorter trip durations (6.19-6.68 min) compared to the longer times recorded during 50% flowering (6.84-6.98 min). Even during early morning hours (06:00-08:00 h), bees foraged more rapidly at full bloom, completing trips in 7.00-7.34 min versus 7.40-7.85 min at 50% flowering. Colony-wise variations were minimal, indicating that external factors such as floral availability and time of day exerted stronger influence on foraging patterns than intra-colony conditions. In contrast, pollen load per forager showed no significant differences between flowering stages, remaining consistent at 10.06-13.14 mg (p = 0.956). All marked bees successfully returned to their hives, confirming strong homing ability. Overall, the findings highlight that honey bees dynamically adjust their foraging frequency and efficiency on sunflower in response to floral abundance and diurnal cues, while maintaining stable pollen collection.