Oxidative Stress and CO₂ Emissions in Honey Bees Following λ-Cyhalothrin and Azoxystrobin Exposure

Honey bees are particularly vulnerable to sublethal doses of plant protection products. In spring, when many crops are flowering, growers often use fungicides from the strobilurins group (e.g. Amistar 250 SC, active ingredient: azoxystrobin) and insecticides from the pyrethriods group (e.g. Karate Zeon 050 CS, active ingredient: λ-cyhalothrin). These compounds may disturb organismal responses to stress factors, among others, by modifying the rate of metabolic processes or inducing oxidative stress. We analysed the impact of sublethal doses of these two preparations acting alone and simultaneously on bees. We assessed their effect on the metabolic rate-evaluated indirectly by analyzing the rate of CO₂ emission-and on changes in oxidative stress markers in worker bees. We did not observe a significant effect of the pesticides on the rate of CO₂ emission. Following insecticide application, malondialdehyde levels increased significantly compared to both the control group and the group treated with both preparations. Glutathione peroxidase activity also increased significantly in bees treated with this preparation. At the dosage used, the fungicide significantly reduced total antioxidant capacity.