Effects of Sublethal Exposure to the Herbicide Atrazine and Insecticide Profenofos on Queen Performance and Colony Strength in Apiary Settings

Honey bees ( Apis mellifera) serve as primary pollinators for plants but are frequently exposed to pesticides. While numerous studies have investigated the impact of pesticides on honey bees in laboratory settings, research conducted in apiaries remains insufficient to fully grasp the true effects of these pesticides on colonies and queens. This study delves into the consequences of sublethal doses of atrazine (a herbicide), profenofos (an insecticide), and their combination on queen honey bees. The following concentrations were tested: For atrazine, 6.25mg/100 g of candy (abbreviated as A0.05), 12.5 mg/100 g of candy (abbreviated as A0.1); for Profenofos, 2.5 μL/100g of candy (abbreviated as P0.02), 3.125μL/100 g of candy (abbreviated as P0.025); and a combination of atrazine 0.05 and profenofos 0.02 in a 1: 1 ratio (abbreviated as A+ P). The research scrutinized aspects such as egg-laying and various parameters linked to colony development and activities, including measuring sealed brood areas, honey reserves, and stored pollen areas. Although neither pesticide affected queen mating potential, both influenced egg-laying capabilities. By day 24 after introduction, only 80% of queens treated with A0.05, A0.1, or P0.025 were capable of laying eggs. Nonetheless, both pesticides had minimal impact on food storage activities and colony vigor. Colonies from the P0.025 group exhibited the lowest brood- rearing activity, while the A0.1 group showed the lowest honey and pollen storage activities. When combined, the two pesticides did not show synergistic effects; instead, intermediate negative effects between profenofos and atrazine were observed. The study indicates short- term effects of these pesticides on colony dynamics.