Respiratory Toxicity of Cupressus sempervirens Essential Oil from Two Different Habitats Against Indian Meal Moth (Plodia interpunctella) and Yellow Mealworm (Tenebrio molitor)

Environmental and health concerns associated with synthetic pesticides have intensified the search for effective botanical alternatives. This study investigated the insecticidal properties of essential oils derived from Mediterranean cypress (Cupressus sempervirens L.) leaves collected from two distinct habitats in Iran (Rudbar and Hasanabad Chalous) against the Indian meal moth (Plodia interpunctella Hübner) and the yellow mealworm (Tenebrio molitor L.). Essential oils were extracted by hydro-distillation and analyzed by GC-MS, revealing 22 and 24 compounds in the Rudbar and Hasanabad oils, respectively, with α-pinene as the dominant component in both. The respiratory toxicity was assessed through probit analysis, calculating both LC50 and LT50 values. The results demonstrated a significant correlation between oil concentration and mortality. Notably, the efficacy was both habitat-dependent and species-specific. The Rudbar essential oil was significantly more potent and faster-acting against P. interpunctella (LC50 = 96.65 µL/L; LT50 = 12.1 h), whereas the Hasanabad oil was more effective against T. molitor (LC50 = 130.90 µL/L; LT50 = 11.8 h). This differential toxicity is linked to their distinct chemical profiles. This study confirms that the habitat of C. sempervirens critically influences the chemical composition and resultant insecticidal activity of its essential oil, highlighting its potential for developing targeted, selective pest control strategies for specific stored-product pests.