Redox metabolic disruptions in the honey bee brain following acute exposure to the pyrethroid deltamethrin

Deltamethrin is a widely used pyrethroid insecticide that has detrimental effects on the redox homeostasis of honey bee (Apis mellifera) brains. The decline of pollinating insect populations, including honey bee colonies, is a growing global concern. This problem results in serious ecological and economic concerns as well as veterinary- and animal health-related issues. In addition, exposure to agricultural pesticides is one of the major contributing factors. Adult worker honey bees were exposed to three sublethal concentrations of orally administered deltamethrin (1.975, 3.95, and 7.9 ng/bee/day; corresponding to LD50/40, LD50/20, and LD50/10) for 48 h. In this study, various redox markers, including glutathione concentrations, antioxidant enzyme activities, total antioxidant capacity, hydrogen peroxide concentrations and lipid peroxidation products, were monitored in brain homogenate samples from honey bees. The results revealed significant changes related to the glutathione system, as indicated by decreases in the GSH/GSSG ratio and GSH concentration in all treatment groups. The activities of the monitored enzymes, such as glucose-6-phosphate dehydrogenase (G6PDH), superoxide dismutase (SOD), and xanthine oxidase (XO), were significantly decreased, highlighting the altered function of the enzymatic antioxidant defense system. Moreover, pronounced lipid peroxidation was detected in the highest-dose group, as indicated by increased malondialdehyde (MDA) levels; however, H₂O₂ levels were unchanged, suggesting the effective activation of ROS-scavenging adaptation mechanisms. The present study provides valuable insights into the molecular mechanisms of deltamethrin toxicity in honey bees, suggesting that redox metabolism is negatively affected. Understanding the exact mechanism of action may contribute to the identification of new possibilities for effective intervention in cellular metabolic processes in the future through the targeted use of novel protective feed additives or other methods, which are of particular importance for animal health as well as for this field of veterinary medicine.