The effect of Artemisia annua essential oil and one of its main components on the biology and enzymatic and non-enzymatic activities of Ephestia kuehniella Zeller (Lepidoptra: Pyralidae)

Abstract

The flour moth, Ephestia kuehniella, is a common storage pest worldwide. One of the most commonly used methods for controlling storage pests is fumigation using synthetic chemical compounds, which have serious negative impacts. In this study, the fumigant toxicity effects of Artemisia annua essential oil and 1,8-cineole, two environmentally safe substances, were investigated on larvicidal activity, developmental stages, cellular immunity, and enzymatic activities of E. kuehniella larvae. The results of fumigation assays on 3^rd instar larvae after 24 and 48h was estimated for A. annua essential oil and 1,8-cineole and lethal concentration (LC) values was calculated. The results indicated higher toxicity of 1,8-cineole over A. annua essential oil. Moreover, prolongation of larval developmental duration and a decrease in pupation period were observed at LC₃₀-treated larvae with A. annua essential oil as well as 1,8-cineole. A significant reduction of total hemocyte count and differential hemocyte count, including the number of plasmatocytes and granulocytes was also observed at LC₃₀ and LC₅₀ concentrations, 24 and 48h post-treatment. The antioxidant enzymes including catalase and peroxidase were significantly increased compared to the control. Similarly, the metabolic enzymes including alanine aminotransferase, aspartate aminotransferase, acid/alkaline phosphatase, lactate dehydrogenase were enhanced. The evaluation of detoxifying enzymes like glutathione S-transferase using DCNB and CDNB substrates, showed a significant increase compared to the control. Conversely, the activity of acetylcholinesterase was significantly decreased compared to the control. The results are indicative of the potentiality of these natural compounds as alternative to classical control measure against this important storage product pest