<p>The effects of pesticides on pollinators are a growing concern due to their crucial role in crop pollination. Although fipronil is widely used, its sublethal effects on honeybee colony performance remain inadequately studied. This study evaluated the toxicity of fipronil to <i>Apis mellifera</i> through laboratory assessments, including lethal dose (LD₅₀) determinations, as well as semi-field and field investigations conducted from 2020 to 2022. These investigations focused on foraging activity, mortality, and colony performance indicators, including brood area, nectar stores, pollen stores, and bee strength. Under semi-field conditions, foraging activity significantly declined to 6.50 bees/m²/2 min on the day of spraying, with increased mortality (45.66 bees/day vs. 6.94 in the control). In the field, bee activity dropped to 5.83 bees/day post-spraying but recovered after 10 days. The brood area showed significant reductions on both the 7th and 14th days, along with similar decreases in nectar and pollen storage. The LD₅₀ values for contact and oral toxicity were determined to be 0.005&#xa0;µg/bee and 0.052&#xa0;µg/bee, respectively. A sharp decline in <i>A. mellifera</i> activity (5.83 bees/day) was observed after fipronil spraying under field conditions compared with the control. A significant recovery in activity was noted by day 10. Brood area and bee strength declined significantly by the 7th day, while pollen area showed no significant change. These findings indicate that even field-relevant doses of fipronil negatively affect <i>A. mellifera</i> colony performance. Therefore, fipronil use should be regulated during pollinator-active periods, and alternative pest management strategies should be considered.</p>