Effects of glyphosate herbicide Roundup® on antioxidant enzymes activity and detoxification-related gene expression in honey bees (Apis mellifera)

Glyphosate (GLY) is a type of broad-spectrum herbicide and has been widely used for weed control. In the past few decades, GLY was generally considered to be low toxic or non-toxic to animals. However, recent studies demonstrated that GLY has adverse effects on honey bees. How honey bees’ internal antioxidant and detoxification system responds to GLY exposure needs to be investigated. In this study, we calculated the median lethal dose (LD50) of GLY in honey bees and evaluate the effect of GLY on detoxification-related gene expression and antioxidant enzyme activities of honey bees. Our results showed that the LD50 of GLY to honey bees at 24 and 48 h were 1773.06 and 537.67 µg active ingredient (a.i.)/bee, respectively, which suggested the low toxicity of GLY to honey bees. Moreover, we found significantly downregulated enzyme activity of superoxide dismutase (SOD), upregulated activities of glutathione S-transferase (GST) and acetylcholinesterase (AChE), as well as upregulated gene expression of CYP9Q1 in the head, and CYP9Q2 in the head and abdomen, which indicated the important roles of GST, AChE, and cytochrome P450 monooxygenase (CYPs/P450s) in protecting bees against GLY stress. Our study will help to clarify the role of antioxidative enzymes and detoxifying enzymes in terms of preventing or limiting GLY stress injury.