Study On Acaricidal Activity Of Arctium Lappa. L And Other Chinese Herbal Medicine Plants Against Panonychus Citri (McGregor)

The citrus red mite,Panonychus citri McGregor(Acari:Tetranychidae),is an important pest mite in the Citrus production.Because of short life cycle and high reproductive rate,the control was based mainly on the frequent use of acaricides.However,repeated use of chemicals has sometimes resulted in the development of drug resistence.As the mites enhanced resistance to chemicals,the use of acaricides had increased year by year.For these reasons,much attention had focused on the potential dangers,directly or indirectly,which caused by the application of toxic chemicals,also raised.Therefore,pesticides and environmentally compatible pesticides,Which was in line with the environmental,healthy,high efficiency,low toxicity,low-residue,become the subject of study. Among them,finding acaricidal ingredients and botanical acaricide from the natural plant is the most attractive and most popular topic.This paper studied the acaricidal activity and oviposition repellent effect of 30 kinds of chinese herbal medicine plants,which belong to 15 families and widely distributed in China's various regions,Extraction and isolation of acaricidal substances of Arctium Lappa.L and its acaricidal action mechanism.The main experimental results was obtained as follows:The ultrasonic extraction of 30 kinds of Chinese herbal extracts plants was been used.Ethanol as extraction solvent,the bioassay methods was used to evaluate acaricidal activity of extracts after 24 h.The results showed that,bioassays on contact acaricidal and oviposition activity and repellent effect of 30 extracts indicated that all 30 kinds of plant extracts(concentration 1g/ml) were lethal to the female adult and egg of Panonychus citri.After 24 h the toxicity of the extracts was different in degree,no negative effects of acaricidal plant extracts were found.Extracts of Coptis chinensis, Aconitum kusnezoffii,Arctium lappa,Foeniculum vulgare caused greater than 90%correted mortality in contact assay against female adult.Whereas extracts of Micromelum falcatum,Sophora Flavescens,Ligusticum sinense,Peucedanum praeruptorum,Magnolia officinalis,Notopterygium incisum,Ligusticum chuanxiong,Acanthopanax gracilistylus,Tagetes patula,Platycladus orientalis resulted in corrected mortality between 60%and 90%.The rest of that was poor.Of the total,the extracts of Sophora F.,Ligusticum s.,Aconitum k.,Foeniculum v.showed preferably acaricidal activity against female adult mite,the LC₅₀ value were between 0.0658～0.1385 g/L.However, whose oviposition corrected mortality rate was only 3.78%～48.16%with the LC₅₀ value as high as 144.1805 g/L～1628.90 g/L.The best plant was Arctium L.with LC₅₀ value of 0.0750 g/L and oviposition inhibition rate of 3.8562 g/L against female adut and egg of the Panonychus citri., respectively.2 The active ingredient of the ethanol extract of Arctium L.was separated use of different polarity solvent,Column chromatography and thin layer chromatography,determination of the contact acaricidal from different fractions obtained.Chloroform portation extracted from Ethanol extract of Arctium L.had the highest extration rate(1.85%),Followed by petroleum ether(0.63%), ethyl acetate of that was lower(0.23%).By the activity assay of leaves of impregnation,the acaricidal activity of three kinds of extracts were evaluated.Part of petroleum ether extraction possed the strongest activity,its LC₅₀ value was 0.0801 g/L and significanly superior to the chloroform extraction with LC₅₀ value of 1.8740 g/L.The results above concluded that the active ingredients from Arctium L.focused on the weakness of polar petroleum ether,chloroform extraction part.Combination of Petroleum ether and chloroform component part of was separated by large column,subdivision column into 4 parts,there were LI-1,L1-2,L1-3,L1-4.By the leaf impregnation bioassay,L1-2 possed the strongest activity,the LC₅₀ value of contact toxicity on mite Panonychus citri,up to 0.0025 g/L.By UV absorption reaction and color ldentification,L1-2 was proved that contained three conjugated double bonds or bond.The chemical compositon of portation L1-2 was anlyzed and identificated by the GC-MS,analysis datum revealed that portation L1-2 contained 34 compounds which were present in the unsaturated fatty substances and accounted for 85.32%of total substance.Fatty substances contained mainly Octadecanoic acid methyl ester, Hexadecanoic methyl ester,Pentadecanoic methyl ester,Triacontanoic methyl ester,9-Octadecanoic methyl ester,8-Octadecanoic methyl ester,11-Octadecanoic methyl ester,8,11-Octadecanoic methyl ester,7,10-Octadecanoic methyl ester,6,9-Octadecanoic methyl ester,10, 13-Octadecanoic methyl ester,9,12-Octadecanoic methyl ester,8,11-Octadecanoic methyl ester,and also a small amount of aldehyde,enol,olefin-type material.3 The reactions to Panonychus citri,was divided into the following phases after treated by L1-2 components(concentration of 4.668μg /μl),The first period(0～5 h),hold still,without significant.The second period of(5～7 h),contantly movement for exciting,uncoodinated behavior, standing instability,body expansion at the early,mostly the color of mite body becamed from dark red to bright red.The third period(7～14 h):spasm associated with a charateristic depression of overturning for over-exciting,with eight leg fully swing staggering,with mite body tilting to the side,with foot cramping,with stop trembling,twitching feet wide,with a small number of the spread of escaping,with waste becoming little and body color turnning into black,with fecundity sharp declining,with mite color change into bright.The fourth period(14～18 h),mite body perfomced stationary and begun to shrink for paralysis.The last period(18～24 h),death related with gradual body contraction.4 Activity of enzymes which were CarE,ACHE,GSTs in mite dynamic and inhibition effects of the active component was researched.The results showed that CarE,ACHE,GSTs enzyme activity was descended as concentration of portation L1-2 incresed in vivo experiments.In vivo experiments, Portation L1-2 had infected effectly on Care firstly and inhibited later.Before 12 h,The special activity of CarE increased by 44.72%,33.13%,27.3%,17.34%,10.08%with the concentration increasing,respectively.After 12 h,the effect on the CarE given rise to infection with the concentration of extract was 0.2344μg/μl.And with concentration increasing,the infection effect on CarE became stronger.After 12 h,the special activity of AChE increased by 27.95%,32.76%, 30.63%,10.18%and 3.69%with the increase in the concentration,respectively.After 24 h,when the L1-2 component concentration was 0.4688×10^-3μg/μl,the AChE of Panonychus citri started to be inhibited and the infection effect enhanced with the increasing of concentration.AChE special activity increased dramatically to 64.07%.When concentration was 4.688μg/μl,the effect to GSTs stired up all the time,those effect became stronger with concentration increased rapidly.After 24 h, when the L1-2 components in the concentration of 0.2344×10^-1μg/μl,GSTs of the citrus mite was inhibited up to 38.94%.The sensitivity to three common enzymes for the active ingredient was not uniform.In initial stage of vivo experiments,the infection effect on GSTs performanced rapidly. With concentration and time increasing,inhibition performanced and rapid increased to ACHE,CarE. These performances showed that the infection effect of L1-2 component on three common enzymes in Panonychus citrus are closely related with the thne and concentration.As time and concentration increased,inhibition gradually enhanced.Arctium L.is common Chinese medicinal herb and rich in resources.Its volatile oil is considered the nutritional value,can be comparable of walnut oil,as a source of botanical pesticides are relatively safe.The activity of unsaturated fatty acids such as 9,12-Octadecanoic acid is reported firstly.The development and utilization of fatty acids of Arctium Lappa.L and the creation of novel botanical acaricide whose ingredient is major in fatty acids of great significance.