اثرات زیرکشنده اسانس‌های درمنه خزری Artemisia annua L.، آویشن باغی Thymus vulgaris L. و دو ترکیب طبیعی آن‌ها (8،1ـ سینئول و تیمول) بر شاخص‌های فیزیولوژیک کرم غوزه پنبه Helicoverpa armigera (Hübner)

The cotton bollworm, Helicoverpa armigera (Hübner), is a destructive and polyphagous pest causing significant economic damage to various crops in Iran and worldwide. A common method for managing this pest is the application of chemical pesticides, but their widespread use poses risks to human health, environmental pollution, pest resistance, destruction of natural enemies, and impacts on non-target organisms. Therefore, it is essential to select a safe and environmentally friendly control method against the cotton bollworm. In recent years, plant-based products like essential oils have gained attention due to their lethal effects on various pest stages. In this study, the oral toxicity of essential oils from Artemisia annua L. and Thymus vulgaris L., and their natural compounds (1,8-cineole and thymol) were evaluated on 3rd instar larvae of the cotton bollworm, 24 hours posttreatment with artificial diet under laboratory conditions (26±1 °C, 65±10 %RH and 16L: 8D h). The toxicity levels (LC values) of Artemisia annua essential oil were LC10: 0.310, LC30: 1.269, LC50: 3.367; for thymol, LC10: 0.342, LC30: 1.572, LC50: 4.522; for Thymus vulgaris essential oil, LC10: 0.474, LC30: 1.987, LC50: 5.340; and for 1,8-cineole, LC10: 0.692, LC30: 2.684, LC50: 6.866 percent. Given the role of antioxidant and detoxifying enzymes in mitigating the toxic effects of these compounds, the impact of sublethal concentration (LC30) of the essential oils and their natural compounds on these parameters was examined at 24 and 48 hours. The activity of detoxifying enzymes, including general esterases, cytochrome P450 monooxygenase, and acetylcholinesterase, significantly decreased in treated larvae compared to controls, while the activity of glutathione S-transferase significantly increased at all time intervals. Although the activity of antioxidant enzymes (catalase, superoxide dismutase, and glucose-6-phosphate dehydrogenase) increased in treated larvae, peroxidase activity decreased. Additionally, non-enzymatic compounds such as glucose, triglycerides, and protein levels significantly decreased in treated larvae compared to controls. The results of this study indicate that the greatest reduction in biochemical compounds in treated larvae was due to the essential oil of Artemisia annua and the natural compound thymol. Therefore, it can be concluded that using Artemisia annua essential oil and thymol from Thymus vulgaris could be considered for developing a natural and environmentally friendly formulation for managing the cotton bollworm.