Oxidative Stress Response of Honey Bee Colonies during Long-Term Exposure at a Frequency of 900 MHz under Field Conditions

Abstract

Overview

This study investigated the oxidative stress and lipid peroxidation in honey bee larvae, pupae, and the midguts of adult bees during a year-long exposure to radiofrequency electromagnetic fields (RF-EMFs) at a frequency of 900 MHz under realistic field conditions.

• Locations: Honey bee colonies were placed at three distinct locations, each exposed to a different electric field level: 30 mV m^-1, 70 mV m^-1, and 1000 mV m^-1.
• Biomarkers measured: Antioxidant enzymes (glutathione-S-transferase [GST], catalase [CAT], superoxide dismutase [SOD]) and thiobarbituric acid reactive substances (TBARS, indicators of lipid peroxidation) were analysed spectrophotometrically.

Findings

• GST activity did not differ significantly based on electric field level or sampling time within each developmental stage, with the highest activity in pupae.
• Both CAT activity and TBARS concentration were consistently highest in the midguts, regardless of exposure conditions.
• Larvae exposed to an electric field level of 1000 mV m^-1 had notably higher TBARS concentrations compared to larvae at lower field strengths.
• This demonstrates increased oxidative stress under higher RF-EMF exposure, especially in the more sensitive larval stage.
• Despite these effects, no direct linear relationship between field strength and oxidative markers was established.

Conclusion

Extended exposure to RF-EMFs at 900 MHz can cause oxidative stress in honey bees, particularly impacting the larval stage. The findings support the adverse biological effects of electromagnetic fields on non-target species, highlighting potential ecological risks and strengthening the connection between EMF exposure and health impacts in bee populations.