Seasonal heavy metal effects on detoxification and antioxidant gene expression in the urban honeybee

Abstract

Environmental pollutants are associated with honeybee colony losses and may show seasonal concentration variations with respect to the environment and plants. In this study, we examined arsenic (As), lead (Pb), and mercury (Hg) seasonal variations in honey and honeybees in urban areas. Seasonal trends in detoxification (CYP9Q1, CYP9Q2, and CYP9Q3) and antioxidant genes encoding catalase (CAT) and superoxide dismutase (SOD1) were also determined in honeybees. Accordingly, As, Pb, and Hg concentrations were significantly increased in summer in both honey and honeybee samples when compared with other seasons. Similarly, the expression level of CYP9Q1, CYP9Q2, CYP9Q3, SOD1, and CAT showed a significant increase in summer honeybees. This increased expression level particularly in summer honeybees indicating an increased summer honeybee exposure and adaptive oxidative stress responses to environmental pollutants, including heavy metals due to increased flight activity when compared with other seasons. Thus, active season honeybees were subjected to environmental oxidative and detoxification stressors when exposed to environmental pollutants, including heavy metals.