Studies On The Biological Activities And Preparations Of Cashew Nut Shell Liquid

In this paper, the antifungal and insecticidal activities of cashew nut shell liquid(CNSL) against selected plant pathogenic fungi and insects were tested using bioassay methods. The effective antifungal components were preliminary isolatied. CNSL emulsion in water (EW) was successfully developed, preparation quality and control efficiency of which were evaluated. The main results were summarized as following:1. The results of antifungal activities showed that, with 2.5g/L of CNSL, the inhibition rates were 8.7⁹3.2% after 48 hours, which followed the sequence of Cytospora mandshurica Miura>Sphaceloma ampelinum (de Bary) Shear>Phomopsis vexans(Sacc.et Syd.)Harter > Gibberella sanbinetti > Gleosporium fructigenum Berk > Botrytis cinerea > Colletotrichum gloeosporioides > Botrytis cinerea Pers. > Physalospora piricpla Nose > Fusicladium sp. The EC₅₀ values of CNSL to Cytospora mandshurica Miura, Phomopsis vexans (Sacc.et Syd.) Harter, Sphaceloma ampelinum (de Bary) Shear, Gibberella sanbinetti, Gleosporium fructigenum Berk, Fusarium oxysporum f.sp.lycopersici were 0.363 g/L, 0.825 g/L, 1.716g/L, 1.893 g/L and 3.642g/L, respectively.2. Preliminary isolation of the antifungal active ingredients from CNSL was sudied. 3 compounds from CNSL sample were isolated by TLC, which was noted as substance 1, 2 and 3, respectively. The antifungal activities of CNSL, substance 1, 2 and 3 to Fusarium oxysporum f.sp.lycopersici were 21.3%, 67.5%, 63.8% and 5.0%, respectively. It showed that substance 1 and substance 2 had fairly strong antifungal activitives, while substance 3 had almost no antifungal activity. Structural identification of the antifungal active component from CNSL should be further studied.3. The results of insecticidal bioassay showed that, the LC₅₀ values of CNSL to Artemia salina and Brevicoryne brassicaeL after 24h were 0.009g/L and 10.692g/L. The LC50 values of the mixtures with the ratios of 1:600, 1:300, 1:150, 1:75 and 1:25 (imidacloprid : CNSL ) were 0.50 g/L, 0.31 g/L, 0.21 g/L, 0.26 g/L and 0.34 g/L, respectively, which were obviously lower than the LC₅₀ of imidacloprid or CNSL (10.69g/L, 0.55 g/L). The co-toxicity coefficient of the mixture were 403.1, 639.5, 875.7, 652.8 and 354.1, respectively. It showed that CNSL had obvious synergistic action to imidacloprid. 4. Development of a HPTLC method for the determination of CNSL. CNSL samples were applied on GF₂₅₄ silica gel plate, developed with the mixture of hexane / methylene chloride (3/7, v/v) for 15 mm, and continuously developed with hexane for 25 mm, detected with the scanner at 210 nm. A series of standard solution were prepared over a range of 2.0-20μg from the standard solution of CNSL. Calibration cures were constructed for CNSL by plotting the peak area [Y-axis] against the amount of compounds [X-axis]. The logarithmic regression equations for substance 1, 2 and 3 were y=2723.4ln(x)+858.88 (R²=0.9806), y=2137.5ln(x)-1289 (R²=0.9300) and y=6532.4ln(x)+4619 (R²=0.9634). Recoveries and C.V.s of CNSL from laboratory-prepared formulations determined by this analytical method were 97.9%¹01.9% and 2.12%³.77%. The precision and accuracy of this HPTLC method were generally fit for pesticide formulation analysis.5. Development and quality evaluation of EW. CNSL EW was developed by selection of emulsifiers. The ingredients of the preparation were CNSL (5%), emulsifiers (12%), xylene (5%), other emulsifiers (3%) and water (adding to 100%). The experiments of thermal storage, cold storage, melt-freeze and the stability of CNSL EW were studied. The results showed the characters of CNSL EW were in accordance with the quality standards of EW preparation.6. The control efficiency of CNSL EW. The results showed that CNSL EW had control efficiency to aphids, the effect increased along with the increased concentration. The corrected mortalities of the preparation diluted 100-fold, 300-fold and 500-fold respectively achieved 56.5%, 32.8% and 10.1% after 1d in the field. The corrected mortalities of the preparation would increase as time went on, which respectively achieved 89.9%, 57.1% and 29.8% after 5d in the field. The corrected mortality of CNSL EW diluted 100-fold after 5d against aphids was equivalent to the effect of imidacloprid WP diluted 2000-fold after 3d. It could be concluded that the control efficiency of CNSL EW was worse than chemical insecticides. However, CNSL had obvious synergistic action to imidacloprid, which help to development of new botanical synergistic pesticide preparation.