Evaluating the Direct and Indirect Toxicity of Nine Insecticides on an Important Predatory Natural Enemy in Rice...

Natural enemies play an important role in the integrated pest management (IPM) of rice crops. Chemical control is commonly used for pest management in rice; however, the compatibility between biological and chemical control within this system has not been thoroughly investigated. This study aimed to evaluate both the direct and indirect toxicity of nine insecticides-tetraniliprole, triflumezopyrim, chlorantraniliprole, pymetrozine, spinetoram, nitenpyram, imidacloprid, emamectin benzoate, and avermectin-against six important predators of rice pests: Cyrtorhinus lividipennis, Paederus fuscipes, Ummeliata insecticeps, Tetragnatha maxillosa, Mendoza cancestrinnii, and Pardosa pseudoannulata under laboratory conditions. The results indicated that tetraniliprole, triflumezopyrim, and chlorantraniliprole exhibited negligible direct toxicity (mortality < 30%) to all six predators and did not significantly affect their predatory activity. In contrast, spinetoram, avermectin, emamectin benzoate, nitenpyram, and imidacloprid showed high direct toxicity (mortality > 99%), significantly reduced predatory activity, and were classified as high to extremely high risk for C. lividipennis. Nitenpyram showed strong direct toxicity (mortality > 99%) to P. fuscipes and was categorized as high risk. Avermectin and emamectin benzoate exhibited high direct and indirect toxicity to all four spider species, significantly reducing predatory activity, and were graded from medium to extremely high risk. Spinetoram reduced predatory activity across all four spider species and exhibited direct toxic effects, posing a high risk to U. insecticeps. In conclusion, pymetrozine, spinetoram, nitenpyram, imidacloprid, emamectin benzoate, and avermectin exerted lethal or sublethal effects on all six predators. Conversely, tetraniliprole, triflumezopyrim, and chlorantraniliprole were regarded as safer insecticides for all six predators.