Abstract: This paper determined the contact-killing and fumigant activities of natural plant product bisdemethoxycurcumin (BDMC) on the important phytophagous mite Tetranychus cinnabarinus (Acari: Tetranychidae) at its different life stages, and studied the repellency effects of BDMC on the mite larvae, nymphs, and adults, and the inhibition efficiency of BDMC on the female mite oviposition under the conditions of 26 ℃±1 ℃, 60%-80% RH, and light cycle 14L∶10D h. The median lethal concentration (LC₅₀) of BDMC at 48 h against female adults determined by slide-dip method was 0.433 mg·mL^-1. At concentration 0.883 mg·mL^-1 (LC₇₀), the contact-killing activity of BDMC against different life stage T. cinnabarinus was in the order of larva > nymph > adult > egg, and the corrected mortality of larvae at 24 h and 48 h was 60.0% and 83.3%, respectively. BDMC had no obvious fumigant activity against different life stage T. cinnabarinus, and the corrected mortality was all less than 3% after treatment 24 h and 48 h. BDMC had stronger repellency activity against the mite, with the repellency rate against larvae at different treatment times all above 85%, followed by against nymphs, and that against adults after 72 h being only 47.8%. BDMC had obvious oviposition inhibition activity against female adults, with the inhibition rate after 120 h reached 89.3%. All the results suggested that the main action modes of BDMC against T. cinnabarinus were contact-killing, repellency, and oviposition inhibition.

Key words: bisdemethoxycurcumin, Tetranychus cinnabarinus, contact-killing, fumigant, oviposition inhibition, repellency