A study on the toxicity of a medicinal plant, Artemisia Annua L. (Asteracea) extracts to the sunn pest, eurygaster integriceps puton (Hemiptera: Scutelleridae)

Abstract

A methanolic extract of Artemisia annua was obtained to evaluate its insecticidal activities against the sunn pest (Eurygaster intefriceps). Also, the responses of general esterase (EST), glutathione S-transferase (GST), alkaline phosphatase (ALP), acid phosphatase (ACP), acethylcholinesterase (AChE) to the plant extract were investigated. Topical application of plant extract on adults showed that the mortality was dose-dependent i.e. with increasing of plant extract concentrations more mortality achieved. Esterase and GST activities were increased in the first 24 h post-treatment. However, the enzymes activities were decreased after 24 h until 72 h. The activities of ALP, ACP and AChE in insect body decreased significantly and inhibition was higher along with increasing concentrations of plant extract. Isozyme electrophoresis profiles indicated that responses of isozymes (EST and GST) to plant extract were decreased after 48 h exposure to extract so that some enzymes bands disappeared. The results indicated that the highest concentration of A. annua extract was the most toxic among the four extracts. The decline of the detoxification ability in insects' tissues might be the main reason for the insecticidal activities.