Effects Of Consolida Ajacis Extract On Biological And Enzyme Activity Of Plutella Xylostella

Large applications of chemical pesticides will produce serious problems,such as pesticide residues and drug resistance.The development of efficient environment-friendly biological pesticides from plant extracts would also achieve effective control against P.xylostella while greatly reducing pesticide residues.Based on this,in this study,the Consolida ajacis seeds were used as materials to explore the effects of extracts from different solvents on the biological activities on P.xylostella,and the effects of ethyl acetate extract with the highest insecticidal activity on a variety of enzyme activities and detoxification enzyme related genes in P.xylostella were studied from the physiological,biochemical and molecular levels.Finally,it was identified and determined that ethyl linoleate with a high content in the extract had the best insecticidal activity for P.xylostella larvae.The main results are as follows:1.Determination of the bioactivities of different solvent extracts of C.ajacis on P.xylostellaThe effects of different solvent extracts of C.ajacis on contact activity,stomach toxicity,selective antifeedant,growth and development inhibition,and oviposition avoidance of P.xylostella larvae were determined.The results of biological activity showed that the ethyl acetate extract from C.ajacis had high contact activity,and the LC₅₀was 5.05 mg/m L after 72 h treatment of P.xylostella;In the stomach toxicity,when the highest concentration of ethyl acetate extract of C.ajacis was 50 mg/m L,the corrected mortality of P.xylostella after 72 h was 67.39%,followed by petroleum ether extract,and the corrected mortality after 72 h of treatment at the highest concentration was 57.36%;In the selective antifeedant effect,the antifeedant rate of ethyl acetate extract was more than 90%after 24 h,48 h and 72 h of treatment with the highest concentration of 50 mg/m L,followed by n-butanol extract,and the selective antifeedant rate was 71.79%after 72 h of treatment with the highest concentration;In the inhibition of growth and development,ethyl acetate extract had the best effect.After feeding P.xylostella larvae at the highest concentration of 50 mg/m L for 3 days,the growth inhibition rate was 66.38%;In the oviposition repelling effect,the selective oviposition repelling rates of methanol,ethanol,n-butanol,ethyl acetate and petroleum ether extracts to P.xylostella adults were 23.59%,31.67%,50.36%,67.85%and 33.51%respectively after 72 h of treatment at the highest concentration of 50 mg/m L.2.Effect of enzyme activity by ethyl acetate extract of C.ajacis on P.xylostella larvaeThe concentration gradient at sublethal dose and the time gradient at LC₅₀level were set up to investigate the activity effects of various enzymes in P.xylostella.The results showed that different concentrations and times would affect the enzyme activity in P.xylostella.After 24 h of treatment at all sublethal concentrations,the activities of ACh E,detoxification enzymes Car E and GST in P.xylostella larvae were inhibited,but induced the activity of protective enzyme CAT.Under the treatment of the same sublethal concentration LC₅₀,the activities of ACh E,detoxification enzymes Car E,GST and protective enzymes POD and SOD increased in varying degrees with the increase of time,but they were still significantly lower than those in the control group,while the CAT activity was activated higher than that in the control group in each period.3.Effects of ethyl acetate extract of C.ajacis on the expression of detoxification enzyme-related genes in P.xylostellaThe expression levels of detoxification enzyme-related genes in P.xylostella were analyzed by RT-q PCR,The results showed that Px GSTD2,Px GSTD4,Px GSTD5,Px GSTE2 and Px GSTE4 were upregulated in the whole time,while Pxae28 and Px GSTE3 were down-regulated in the whole time.4.Gas Chromatography-Mass Spectrometer analysis of activity and insecticidal components of ethyl acetate extract of C.ajacisThe GC-MS was used to analyze the components of the ethyl acetate extract of C.ajacis.The results showed that it contained 24 chemical components such as esters,amides,and alkanes.The results showed that after 72 h,the LC₅₀of the 4 components to P.xylostella were 0.60 mg/m L,6.13 mg/m L,0.26 mg/m L and 2.03 mg/m L respectively.To sum up,the results of this paper provide a reference for the subsequent disclosure of the action mechanism of C.ajacis extract,and also provide a reference for the control of P.xylostella and the development of botanical biopesticides.