Toxicity and deleterious effects of Artemisia annua essential oil extracts on mulberry pyralid (Glyphodes pyloalis)

Botanical extracts are an important source of bio-pesticides and are generally considered safe to the environment. Artemisia annua L, a medicinal plant, well known for its antimalarial potential, was evaluated as a source of a type of essential oil collected during vegetative growth stage against Glyphodes pyloalis Walker. The main chemical components of the essential oil at vegetative stage of Artemisia annua was analyzed by GC- MS and contained 1,8-cineole (18.68%), Camphor (11.4%), α-Pinene (9.3%) and 3-Carene (6.3%). The LC₅₀ of this plant oil was estimated to be 0.652% W/V and 2.585 μL/L air incorporated orally and fumigation, respectively. The digestive enzymes such as α-amylases, Proteases, Lipases and α- and β-glucosidases were considereably inhibited in treated larvae compared with controls. Similarly, the amount of protein, glucose, and triglyceride were decreased in the treated larvae by methods used. The lower hemocyte numbers, nodule formation and activity of phenoloxidases after injection of Beauveria bassiana and latex beads showed its EO effect on immunity. The anatomy of the larval midgut after treatment showed degeneration in digestive cells. Emerging adult's ovaries showed significant changes in the ovarian sheath and lack of yolk spheres. The present investigation in accordance with our previous studies may ultimately lead to a formulation in controlling this notorious pest especially in mulberry orchards where the use of conventional chemicals is restricted.

Keywords: Anatomy; Artemisia annua; Enzyme activities; Essential oil; Glyphodes pyloalis; Immune.