No chronic effects on biochemical biomarkers, feeding and survival of carnolian honeybees (Apis mellifera carnica) after exposure to nanosized carbon black and titanium dioxide

Honeybees (Apis mellifera) are important pollinators threatened by environmental pollution, plan protection products and other potential contaminants. Due to an extensive predicted use of engineered nanomaterials (NMs) in agriculture the impact on honeybees should be investigated. We studied the 10-days chronic dietary effect of carbon black (CB) and titanium dioxide (TiO2) NMs on the antioxidant activities, cholinergic function, feeding behaviour and survival of honeybees. Exposure of honeybees Apis mellifera carnica to TiO2 and CB NMs (1 mg ml-1) did not affect the feeding and survival. No alteration of catalase, acetylcholinesterase and glutathione S-transferase enzymatic activity was noticed in the brain of honeybees, indicating that TiO2 and CB NMs at the tested exposure dose had no adverse effects on honeybees. Currently predicted environmental concentrations for TiO2 and CB NMs are significantly lower than the concentration tested in the current study. Based on our findings we conclude that the potential use of TiO2 and CB NMs in agriculture is currently safe for honeybees at the tested concentration level and presents potential advantages compared to other NMs with known toxic potential.