Chronic carbendazim exposure disrupts behavioral responses and redox-regulatory mechanisms in non-target detritivore Nauphoeta cinerea nymphs.

Abstract

Carbendazim is widely applied in agriculture to control various fungal diseases during pre-harvest and post-harvest processes owing to its efficacy and cost-effectiveness. However, environmental and food contamination by carbendazim has become a global health issue. Indeed, the declining biodiversity of beneficial insects owing to agricultural intensification is currently of keen concern to the scientific community. The toxicological responses of Nauphoeta cinerea nymphs, a non-target insect, to ecologically realistic concentrations of carbendazim at 0, 0.25, 2.5, 5.0 and 25 μg/L for 50 uninterrupted days were assessed. Neurobehavioral data generated by video-tracking software revealed that chronic nymphal exposure to carbendazim significantly diminished the path efficiency, body rotation, maximum speed, turn angle and distance traveled but increased the immobility time, total time of freezing and episodes of freezing in insects. The deterioration in the locomotor and exploratory abilities of carbendazim-exposed insects was substantiated by high heat map intensity and reduced track plots. Further, chronic carbendazim exposure diminished acetylcholinesterase activity in head of the insects. Chronic carbendazim exposure significantly decreased antioxidant defense mechanisms but increased nitric oxide, hydrogen peroxide and lipid peroxidation levels in fat body, midgut and head of exposed insects. Activities of acid and alkaline phosphatases which play important roles in detoxification and metabolic processes were also markedly decreased in carbendazim-exposed insects when compared with control. Altogether, carbendazim represents an ecological threat to non-target insects through induction of oxido-inflammatory injury, providing valuable insights into the behavioral dysfunction and toxicological mechanisms of carbendazim in beneficial insects.