Studies On The Botanical Insecticide Microemulsion And Emulsifiable Concentrate Of Acorus Calamus L.

1. Acorus calamus L. is a potential insecticidal plant, in whichβ-asarone is the main compound with insecticidal activity. Many reports with the plant are mainly in the field of isolation and identification for the active ingredients, but there are not any insecticide products. Aimed to exploit botanical insecticides so as to realize safe and green pest control, the microemulsion (ME) and emulsifiable concentrate (EC) of Acorus calamus L. were successfully developed.2. Adopting the methods of methanol soaking and supercritical fluid CO₂ extraction (SFE-CO₂), the contact toxicity of extracts obtained by the two methods from Acorus calamus L. rhizome against adults of Rhyzopertha dominica Fabricius and Sitophilus zeamais Motschulsky were studied with the drug-film method in this paper. The results showed that the extracts rate of Acorus calamus L. rhizome by methanol soaking method and SFE-CO2 method were 9.44% and 5.51%, respectively. Extracts obtained by the two methods from Acorus calamus L. rhizome all had good contact toxicity against adults of R. dominica and S. zeamais. At 4 days after treatment, the LC₅₀ of extracts from Acorus calamus L. rhizome obtained by methanol soaking method and SFE-CO2 method against adults of R. dominica were: 1.30 mg/mL and 1.92 mg/mL respectively; while the LC₅₀ of extracts against adults of S. zeamais were: 9.04,15.38 mg/mL respectively.3. The quality control of botanical insecticide is a key role in the development of formulation. The content ofβ-asarone in the extracts from Acorus calamus L. rhizome obtained by methanol soaking method is 24.39%, using HPLC analytical method of which the standard deviation, coefficient of variance (CV) and recovery was 0.34, 1.37% and 98.84%～100.44% respectively. The index showed that the HPLC analytical method is eligible.According to the theories of composite membrane R-ratio and HLB, without co-solvent or co-surfactant added, the defined concentrations of pesticide emulsifier 500# in the system were 1%, 3% and 5%, and then different non-ionic surfactants were added respectively. Scanning at the temperature range of 0～60°C, the eligible system should be transparent or semitransparent at certain point. After this system was adjusted by quality test, the optimal system was selected finally. The extracts of Acorus calamus L. rhizome by methanol soaking method had been formulated to ME, a formulation comprising 30% extract (about 7.32%β-asarone), 1% pesticide emulsifier 500#, 20% Tween20 and 49% water. According to the related universal standard of pesticide, the quality indexes for 7%β-asarone ME were established.The results of bioassay indicated that the ME had good bioactivities against both 3 instar nymphaes of Nilaparvata lugens (Stal) and 3 instar nymphaes of Blattella germanica, while weak bioactivities against adults of R. dominica and S. zeamais. The corrected mortality at a 100 fold dilutin to 3 instar nymphaes of Nilaparvata lugens (Stal) was 70.11% at 2 days post-treatment. Using drug-film method, the mortality at 174.00 mg/mL to 3 instar nymphaes of Blattella germanica was 93.33% in 48 hours after treatment.4. With respect to the use of xylene, there are generally disadvantages from an environmental and human health viewpoint. To solve this problem, using ethyl as solvent and choosing 9 emulsifiers, the extracts of Acorus calamus L. rhizome by SFE-CO₂ method had been formulated to 9%β-asarone EC, a formulation comprising 40% extract (about 9.76%β-asarone), 8% 4103, 52% ethyl. The quality test showed that the formulation is eligible.The results of bioactivities suggested that 9%β-asarone EC had good bioactivities against 3 instar nymphaes of Nilaparvata lugens (Stal), 3 instar nymphaes of Blattella germanica and adults of R. dominica and S. zeamais. The corrected mortality at a 200 fold dilutin to 3 instar nymphaes of Nilaparvata lugens (Stal) was 89.16% at 3 days post-treatment. With drug-film method, the mortality at 145.00 mg/mL to 3 instar nymphaes of Blattella germanica was 96.67% in 48 hours after treatment. At 20 days post-treatment, the mortality at 800 mg/kg to adults of R. dominica and S. zeamais was 91.11%, while the mortality at 600 mg/kg to adults of S. zeamais was 94.44%.