Toxicity and Oxidative Stress Induced in Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) Treated with Some Insecticides
2019
Hamama, H.M. | Fergani, Y.A.
Integrated pest management of herbivorous pests relies on combining bio-insecticides and chemical insecticides for a satisfactory population control. The present study focused on evaluating the comparative toxicity of five insecticides, with different modes of action, against third and fifth instar larvae of Spodoptera littoralis and their influence on extent of oxidative stress in insect via detecting vitamin C content as well as measuring the activity of phenol oxidase (PO), catalase (CAT), peroxidase (POX), glutathione-S-transferase (GST) antioxidant enzymes compared to control. The results revealed that emamectin benzoate and indoxacarb were the most potent insecticides among the selected insecticides, based on their respective LC₅₀ values. Thiacloprid, indoxacarb and emamectin benzoate significantly reduced Vitamin C content. Almost all treatments significantly increased PO activity. Only emamectin benzoate and Bacillus thuringiensis significantly induced POX activity. Indoxacarb and emamectin benzoate increased CAT activity in both instar larvae, whereas thiacloprid and indoxacarb decreased GST activity. In conclusion, emamectin benzoate and indoxacarb were the most potent insecticides. Activity of oxidative stress biomarkers upon insecticidal pressure has showed variable response.
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