The Effect Of Fluazinam On Panonychus Citri And The Preliminary Study On Its Mechanism

The citrus red mite,Panonychus citri,is a key pest of citrus,which effecting the citrus industry and causing severely damage in China.At present,chemical control is still the main measures to prevent and control the pest.However,frequent and redundant use of chemicals has caused the increasing number of cases of pesticides resistance.Therefore,selecting efficient,green and accurate control agents is an important measure to control the P.citrus.In this study,Fluazinam was choosed to determine the toxicity of P.citrus by leaf-dipping method,and the field trial was evaluated in comparion with other five pesticides.At the same time,based on high-throughput Illumina sequencing,P.citrus was collected after treatment by Fluazinam.The transcriptome data and real-time fluorescence quantitative technology were used to explore the molecular response of P.citrus under Fluazinam stress.The results are as follows:1)The results of the toxicity test showed that Fluazinam showed high toxicity to P.citri(LC₅₀0 of 16.844 mg/L^-1),which is also used as a protective fungicide.SYP-9625 and cyflumetofen positively had excellent toxicity to adult mites among the six tested pesticides,with LC₅₀0 of 0.818 mg/L^-11 and 4.645 mg/L^-11 respectively.But the LC₅₀0 value of spirotetramat was 417.089 mg/L^-1.The toxicities of the six pesticides in the laboratory were in order of SYP-9625,cyflumetofen,fluazinam,pyridaben,etoxazolea and spirotetramat.2)The results of field trial efficacy test showed that as a broad-spectrum efficient fungicide,Fluazinam has good control effect on P.citri which not less than the traditional acaricides.The control effect of Fluazinam was 81.81%on the first day and 92.90%on the 10th day.The control effect was still higher than that of pyridaben on the 30th day after the treatment.During the six contrast medicines SYP-9625 had good quick-acting and long-lasting effects on P.citri.,whose control effect was 88.90%in the first day and over 95%in the last 30 days.It also showed good control effect with Cyflumetofen which control effect was over 90%in 30 days.Pyridaben has good quick-acting but poor long-lasting.The control effect is 84.66%on the first day after treatment but only 56.34%on the 30th day.The efficacy of Ethacazole and Spironolactone was lower than that of other tested pesticides on the first day.After 15 days,their efficacy became 94.49%and 87.94%,while Spirotetramat’s efficacy was 85%more than Ethacazole’s 77.08%on the 30th day.3)Total 18771 genes were successfully annotated through the analysis of transcriptome data,including 59 cytochrome P450 genes,23 glutathione S-transferase genes,5 carboxylesterase genes,11 superoxide dismutase genes and 15 catalase genes.The GO enrichment analysis showed that the genes were mainly enriched in detoxification metabolism and catalytic activity in 6h treatment.The highest enrichment function items were redox process and oxidoreductase activity in 24h treatment,Redox is still an important function item of go enrichment in 48h treatment,and the combination of cofactors and coenzymes also shows a high degree of enrichment.The KEGG enrichment pathways were the degradation of valine,leucine,isoleucine and the abnormality of ribosome in 6h treatment.That was proteasome and oxidoreductase in 24h treatment,which was similar to the results of oxidation-reduction and oxidoreductase activity enrichment found in GO enrichment function item in 24h treatment.The enrichment pathways was glycolysis and tricarboxylic acid in 48h treatment.Acid cycle is closely related to energy synthesis in organism.4)The qPCR results showed that Fluazinam could inhibit the expression of P450 and CarE genes in citrus P.citri.These two genes were significantly down regulated in 24h treatment,and the expression of CarE gene returned to normal in 48h treatment,while P450 gene was still inhibited to some extent.Therefore,it is suggested that P450 gene is more affected than CarE gene.The expression of MnSOD and CAT gene in P.citri was significantly up-regulated 24hours after fluazinam treatment,and the expression of Cu-ZnSOD gene was inhibited,and the difference was not significant compared with that of the control group.Combined with the characteristics of uncoupling agent and inhibition of energy synthesis of Fluazinam in other organisms,it was suggested that MnSOD gene and CAT gene might play an important role in the role of Fluazinam in P.citri.In this study,through the evaluation of the control effect of Fluazinam and the analysis of transcriptome data on P.citri under the stress of the agent,a new chemical selection was provided for the control of P.citri,and gave a preliminary study on the mechanism of action of Fluazinam on P.citri...