Threats of multiple pesticides to a predator: Toxicity and sublethal impacts on Orius nagaii

Pesticide applications inevitably affect agricultural ecosystems and their components, particularly beneficial insects. This study evaluated the impacts of three pesticides cypermethrin, avermectin, and sulfoxaflor on the predatory insect Orius nagaii Yasunaga. We focused on acute toxicity, predation behavior, reproduction, and detoxification mechanisms. Our results showed that all three pesticides significantly affected O. nagaii, with cypermethrin being the most and sulfoxaflor the least toxic. Pesticide exposure altered gut structure and negatively affected predation and reproductive capabilities, especially at higher concentrations, with avermectin and sulfoxaflor notably reducing egg production. Detoxification-related gene and enzyme analyses revealed differential responses across treatments. Cypermethrin upregulated glutathione S-transferase (GST) and peroxidase (POD) activities, while avermectin significantly induced dual oxidase (Doux). Sulfoxaflor increased GST activity, but did not affect superoxide dismutase (SOD) or catalase (CAT). Key CYP genes (CYP6A2, CYP6B7, CYP301A1, and CYP4C1) showed differential expression patterns. CYP6A2 was significantly modulated by all the treatments, CYP6B7 by cypermethrin, and CYP301A1 by avermectin and sulfoxaflor. CYP4C1 was downregulated by sulfoxaflor. In conclusion, although these pesticides effectively control pests, they adversely impact beneficial insects like O. nagaii. Rational pesticide use is essential for protecting natural enemy insect populations. Future research should focus on specific detoxification pathways and species-specific responses to optimize integrated pest management strategies.