Abstract: A laboratory test was conducted on the acaricidal bioactivity of natural and cultivated Artemisia annua leaves acetone extracts against Tetranychus cinnabarinus. The LC₅₀, 48 h of natural and cultivated A. annua leaves acetone extracts was 0.295 and 0.567 mg·ml^-1, respectively, i.e., the acetone extract of cultivated A. annua leaves had a higher acaricidal bioactivity. By column chromatography, a total of 19 and 17 fractions were isolated from the natural and cultivated A. annua leaves acetone extracts, respectively. At the concentration 2.5 mg·ml^-1, the 11th fraction of the extract of natural A. annua leaves and the 13th fraction of the extract of cultivated A. annua leaves could kill all test mites after treated for 48 h. The toxicity test showed that the LC₅₀, 48 h of the 11th fraction of the extract of natural A. annua leaves was 0.120 mg·ml^-1, and the LC₅₀,48 h of the10th, 12th, and 13th fractions of the extract of cultivated A. annua leaves was 0.144, 0.163, and 0.117 mg·ml^-1, respectively. This study suggested that the acaricidal activity of the acetone extract of cultivated A. annua leaves against T. cinnabarinus was superior to that of the natural A. annua leaves.

Key words: Increasing air CO₂ pressure, Litchi chinensis, Photosynthesis Free redical yield