Toxicity of Artemisia annua (Asteraceae) essential oil on the tea mealy bug,Pseudococcus viburni Sigornet (Hemiptera: Pseudococcidae)

A combination of bioassay and biochemical approaches were used to determine toxicity of Artemisia annua essential oil (AaEO) Pseudococcus viburni. AaEO via leaf dipping bioassay showed LC₅₀ values of 0.693 and 0.419% after two time exposures. Different concentrations of AaEO caused deterrence index between 28.58 to 86.26% by the calculated ED₅₀ of 0.4%. Although, α-esterase activity using α-naphtyl acetate increased in the treated nymphs by AaEO after 24 hours but it showed the lower activity in the treated nymphs using β-naphtyl acetate. Glutathione S-transferase assayed by CDNB showed the higher activity in the treated nymphs than control after 24 hours while the adverse results gained not only after 48 hours but also after 24 hours by using DCNB. No significant differences were found in the activity of alanine aminotransferase versus control, but aspartate aminotransferase and γ-glutamyl transferase showed the statistically higher activities in the treated nymphs in comparison with control. Activities of aldolase and lactate dehydrogenase were significantly lower than those of control. Only acid phosphatase showed the significantly altered activity in the treated nymphs in comparison with control after 24 hours. Results of our study indicated significant toxicity, deterrence and physiological effects of AaEO on P. viburni.