Biological Activities And The Mechanism Of Elsholtzia Densa Var.ianthina Essential Oil And Terpenoids Against Paratrioza Sinica

Lycium spp.is cultivated in China for a long history.It has important medicinal value and economic value.The damage caused by P.sinica seriously affects the growth and quality of Lycium spp.In recent years,due to the increasingly obvious disadvantages of chemical pesticides,like pesticide residue and pollution.So,it is important to find environmentally friendly pesticides to control them.E.densa var.ianthina is a kind of aromatic plant,which widely distributed in Inner Mongolia.In order to further develop and utilize this kind of aromatic plant,and seek the green prevention and control way of P.sinica.In this study,the E.densa var.ianthina essential oil was extracted by distillation and analyzed by GC-MS.Using residual film and immersion method to test the bioactivity of E.densa var.ianthina essential oil and 12 terpenoids on P.sinica.The activity effects of 12 terpenoids about acetylcholinesterase(ACh E),glutathione-s transferase(GST)and carboxylesterase(Car E)were determined by biochemical methods.The lethal mechanism of 2-ethylimidazole and Cuminalcohol on P.sinica was analyzed by transcriptome DEGs analysis.And the comparative analysis on the effect and mechanism of 12 terpenoids which were binary mixtures.These will provide a theoretical basis for the manufacture of botanical insecticides.The results are as follows:1.The extraction rate of E.densa var.ianthina essential oil was 0.25%,containing17 components of E.densa var.ianthina essential oil,which accounts for 83.93%of the total and 9 of them were more than 1%.They are cuminalcohol(27.07%),Methyl 3-bro Mo-2-oxobutanoate(18.67%),2-allylbicyclo[2.2.1]heptane(16.57%),palmitic acid(6.08%),stearic acid(3.66%),2-ethylimidazole(3.34%),caryophyllene(2.83%),(1E,4E,8E)-?-humulene(1.2%)and d-cadinene(1.08%).2.The results showed that E.densa var.ianthina essential oil had a repellent effect on the adults of P.sinica.The maximum repellent rate was 21.8%at 3 hours.The median lethal concentration in adults was 5.47 m L/L.The median lethal concentration to the third and fourth instars nymphs was 13.06 m L/L and 19.05 m L/L,respectively.The median lethal concentration of the fifth instar nymphs was more than 20.0 m L/L.3.In 12 kinds of terpenoids,1,8-cineole,4-allylanisol(0.1%)and 2-ethylimidazole(0.1%)that all have repellent effects on the adults of P.sinica.But?-pinene(0.1%)and?-pinene(0.1%)have attractive effects.The toxicity of cuminalcohol and cuminaldehyde to nymphs was the best.The LC₅₀ of cuminalcohol to the third,fourth and fifth instars nymphs were 2.78 m L/L,3.20 m L/L and 4.45 m L/L,respectively.The LC₅₀ of cuminaldehyde were5.31 m L/L,8.54 m L/L and 12.58 m L/L,respectively.The toxicity of 2-ethylimidazole and cuminalcohol to adults was the best,with LC₅₀ were 0.52 m L/L and 2.17 m L/L respectively.4.Effects of binary mixtures of 12 terpenoids on mortality against P.sinica adults.For66 binary combinations,of which 19 combinations showed a significant synergistic effect,while 21 combinations showed a significant antagonistic effect on mortality,and 26combinations showed no effect.The combination of dihydrocarvone and l-carvone had the strongest synergistic effect,?²=113.6,and the mortality rate was 98.4%.The mortality rate of the combination of l-carvone and d-carvone was the best,reaching 98.6%,?²=61.4.Among all binary combinations,L-carvone had the most number of synergistic combinations,while the antagonistic was the least.And the l-carvone was the best synergistic substance.5.In 12 kinds of terpenoids,there were 7 substance existed inhibitory activities on ACh E of P.sinica.The inhibitory rates were in the order of 4-allylanisole(95.0%)>cuminaldehyde(91.4%)>1,8-cineole(88.0%)>?-pinene(74.2%)>d-carvone(66.9%)>l-carvone(42.0%)>dihydrocarvone(35.2%).Caryophyllene,cuminalcohol,2-ethylimidazole,limonene and?-pinene have a little inhibitory effect on ACh E.12 terpenoids had different inhibited effects on glutathione s-transferase of P.sinica.The inhibition rate of l-carvone(65.4%)and cuminaldehyde(58.8%)was the best.While 4-allylanisole,2-ethylimidazole and limonene had lower inhibition rate,28.5%,27.6%and 22.6%,respectively.Cuminaldehyde,dihydrocarvone and 1,8-cineole had inhibitory effects on Car E.Cuminaldehyde had the strongest inhibitory effect with an inhibitory rate of 33.4%.4-allylanisole,?-pinene,d-carvone,l-carvone,caryophyllene,cuminalcohol,2-ethylimidazole and limonene had an activation effect on Car E,cuminalcohol had the strongest activation effect with 51.8%.6.Transcriptome sequencing of P.sinica adults that were treated with 2-ethylimidazole,cuminol and control respectively.A total of 188590 Unigene sequences were assembled.42,461 Unigene sequences were successfully annotated,accounting for 22.51%of the whole genome.Among GO annotations,most genes were annotated in the molecular function class.In the KOG,the most annotated functional group was General function prediction only.KEGG Pathway analysis showed that Translation contained the most annotated genes.DEGs analysis confirmed that the mechanism of action between cuminalcohol and 2-ethylimidazole was completely different in.DEGs analysis showed that the mechanism of action between cuminol and P.sinica.There were 767 DEGs between cuminalcohol and control.359 were up-regulated and 408 were down-regulated.There were 907 DEGs between 2-ethylimidazole and control,among which 334 were up-regulated and 573 were down-regulated.Those DEGs were mainly related to growth,development and metabolism.For treated by cuminalcohol group,9 DEGs were related to mitochondrial electron transport chain,2 DEGs were annotated in CYP450,GST and glutamate receptor contained 1 DEG respectively.In 2-ethylimidazole group,40 DEGs were related to insecticide target and detoxification metabolism,which contained mitochondrial electron transport chain genes(32 DEGs),glutamate receptor(3 DEGs),heat shock protein(2 DEGs),voltage-gated channel protein(1 DEG),transport protein(1 DEG)and phenol oxidase(1 DEG).Taken together,the significant toxic effect of E.densa var.ianthina essential oil on P.sinica.L-carvone was the best synergist substance.The toxicity of 2-ethylimidazole and cuminol to P.sinica was the best,and their insecticidal mechanism may be related to mitochondrial electron transport chain and CYP450.