Abstract: Extraction of insecticide constituents from Trigonella foenum-graecum L. by supercritical fluid CO₂ extraction (SFE-CO₂) method was optimized and the contact toxicity of extracts to Rhyzopertha dominica Fabricius were assayed. The extraction method was optimized with orthogonal design experiments. Contact toxicity and efficiency of extraction were used as value standards. The results showed that the optimal extraction was achieved at 55℃ under 25 MPa of pressure,  the modifier was 95% alcohol,  and the rate between seeds powder and modifier was 200 g∶30 mL. Extraction pressure and modifier volume showed significant effect to extraction procedure, while extraction temperature and modifier concentration showed less effect. The extracts loaded on filter paper showed toxicity to adult R. dominica. An extraction rate of 5.96% was achieved at theoptimal condition,  and the toxicity was increased obviously with the LC₅₀ value of 65.03 μg/cm² for R. dominica treated on filter paper for 3 days and then cultured normally for one week. The results indicated that the extracts have high insecticide activity on R. dominica.

Key words: Trigonella foenum-graecum, supercritical fluid extraction, orthogonal experiment, Rhyzopertha dominica, contact toxicity