A molybdenum coordination complex that enables honey bees to mitigate the sublethal toxic effects of fipronil

This study deals with the effect of the molybdenum-based complex Na ₂ [Mo ₂ O ₄ (EDTA)] used as dietary supplement for the protection of honey bees A. mellifera against deleterious effects of pesticides. Fipronil is a pesticide that is particularly toxic to bees,. In this study, we demonstrate that feeding bees in cages with a 20 mg/L complex solution in sucrose syrup does not significantly alter the value of this lethal dose. However, significant effects are observed at sublethal doses. When bees receive doses of 0.5 ng/bee of fipronil by contact, PER experiments show that their cognitive abilities are significantly reduced. In this study, we demonstrate that bees that have been pre-fed with Na ₂ [Mo ₂ O ₄ (EDTA)] are not affected by this decline in cognitive ability and that a protective effect is clearly evident. This effect is not specific to Fipronil. In fact, in the second part of this study, we show that bees that ingested a cocktail of four pesticides had a higher mortality rate than the control group, but that bees exposed to both this cocktail and the Mo-complex had a mortality rate comparable to that of the control group, thus demonstrating a more comprehensive protective effect. The regulation of molybdenum enzymes such as xanthine oxidase is one hypothesis to explain this effect. In the final part, preliminary results are presented to assess the impact of feeding with our complex on xanthine oxidase levels.