Abstract: In this paper we reported the bioactivities of ethanol extracts from 20 medicinal plants against Rhizopertha dominica (Fab.) using drug-film method and filter paper diffusion method. The results of the contact tests showed that the extract of Trigonelia foenum-graecum was most effective on the pest, followed by Cnidium monnieri and Acorus gramineous respectively. At 0.39 mg/cm² treatment, T. foenum-graecum extract showed 100% mortality at 48 h post-treatment. C. monnieri and Aconitum carmichaeli had marked repellence effect against R. dominica. C. monnieri extract had better contact and repellence efficacy. The LD₅₀ of T. foenum-graecum plant extract against R. dominica after 72 h treatment was 19.94 μg/cm².

Key words: Plant extract, contact toxicity, repellency, Rhizopertha dominica (Fab.), Trigonelia foenum-graecum