Study On The Bioactivity Of Croton Tiglium Extracts Against Plutella Xylostella L.

This experiment was conducted to study bioactivity of extract of Croton tiglium against Plutella xylostella L.,to get components of high antifeedant activity.Modes of action such as effectiveness of stomachtoxicity,inhibition for growth and development and oviposition repellent role of crude extract of Croton tiglium on Plutella xylostella L.were also researched in this experiment,the results are as belows:1,Industrial alcohol was used as the solvent.Crude extract of Croton tiglium was acquired by using ultrasonic cell disruptor to conduct vibratory extraction.Extraction ratio was 19.59%.With a concentration of 10mg/ml,the selective antifeedant rate from ethanol solution of crude extract of Croton tiglium against Plutella xylostella L.was 73.84%.2,Antifeedant rate that against 3rd-instar larvae of Plutella xylostella L.increased as the concentration of crude extract of Croton tiglium increases,the regression equation was y=1.6787+4.0459(r=0.9725),the AFC₅₀(effective cone.causing 50%antifeedant rate) was 3.70±0.33mg/ml.3,Crude extract of Croton tiglium had significant growth and development inhibition activity against Plutella xylostella L.,the regression equation was y=1.6473x+3.9876(r =0.9354),the AGC₅₀(effective cone.causing 50%growth and development inhibition rate) was 4.12±0.36mg/ml.4,Crude extract of Croton tiglium had strong oviposition inhibition activity against Plutella xylostella L.,and as the solution concentration increased the effect became more obviously,the regression equation was y=1.6905x+3.9172(r=0.9850),the AOC₅₀ (effective cone.causing 50%oviposition repellent rate) was 4.37±0.37mg/ml.5,The effect of crude extract of Croton tiglium for contact toxic activity and stomach toxic activity against larvae of Plutella xylostella L.was not obviously.6,Crude paste extract of Croton tiglium was added into 200ml Distilled Water(1:10, V/V),and put into a tap funnel.Extraction was conducted by Lipuid-Lipuid Partition with ligarine,ether and ethyl acetate,and the extracting solution was concentrated into thick paste in turn.With a concentration of 10mg/ml,the selective antifeedant rate of ethanol solution of extract of ligarine,ether,ethyl acetate and water against 3rd-instar larvae of Plutella xylostella L.were 84.99%,29.56%,17.98%and 6.78%,respectively.Among them, the selective antifeedant rate of ligarine extract ethanol solution had 11.15%increase compared to crude extract of Croton tiglium ethanol solution at the same concentration.7,The Croton tiglium extract of ligarine was subjected to silica gel column chromatography gradient eluting with ligarine,ethyl acetate and methanol.The eluate I (the combined products of ligarine:ethyl acetate(50:50,V/V) and ethyl acetate:methanol (90:10,V/V) with a concentration of 10 mg/ml had the highest antifeedant rate against 3rd-instar larvae of Plutella xylostella L.,which was 97.39%.Compared to the predecessor process,it increased 12.4%.8,Eluate I was further purified by TLC,using ligarine:ethyl acetate:ethanol(10:3: 1,V/V/V)as elution to afford I-2 which has the highest antifeedant rate against 3rd-instar larvae of Plutella xylostella L.,which was 99.65%,increasing 2.26%compared to the predecessor process.