Resistance Monitoring Of Chilo Suppressalis (Walker) In Sichuan Province And Transcriptome Analysis Of Induction By Cyantraniliprole

Chilo suppressalis Walker is one of most important insect pests with wide distribution in rice production.During the recently years,C.suppressalis has developed serious resistance to some chemical insecticides because of the extensive use of insecticides.Cyantraniliprole is a new O-aminobenzamide pesticide developed by Dupont,which lead to insect death ultimately though binding to the special point of the ryanodine receptor（Ry R）in the insect pest.In this paper,the resistance levels of C.suppressalis in seven areas of Sichuan Province to 4 kinds of conventional insecticides were investigated and the preliminary metabolic mechanism to triazophos was also explored.Moreover,the relative expression levels of four resistant-related P450 genes between the relatively sensitive strain（HN-Lab）and field-resistant populations were detected with qRT-PCR.The transcriptome sequencing was used to analyze the induction effect of cyantraniliprole on the differentially expressed transcripts（DETs）in the C.suppressalis.The full text is summarized as follows:1.The resistance levels of seven field populations of C.suppressalis to four conventional insecticides,including monosultap,triazophos,chlorpyrifos and abamectin,were monitored using the topical application method in 2018-2019.The results showed that all field populations possessed a moderate level of resistance to triazophos（with resistance ratio（RR）of 23.9-to 83.5-fold）.All field-collected populations had a low or moderate level of resistance to chlorpyrifos（RR 1.7-to 47.1-fold）and monosultap（RR 2.7-to 13.5-fold）and either classed as susceptible or low resistance to abamectin（2.1-to 5.8-fold）.2.The HN-Lab strain and XW19 population with higher resistance of triazophos（RR﹦68.7-fold）were peformed the synergism experiment and found that that the synergist PBO showed the strongest synergism on the triazophos toxicity to the tested two strains,with the synergistic ratio（SR）of 2.4 and 3.4 respectively.Moreover,the activity of detoxification enzymes for the 6 field populations collected in 2019 was measured and found that Car E,GST and P450 activity extremely significantly differed among the 6 field populations（P<0.001）,we also analyzed the correlation between the resistance levels of four insecticides and the three kinds of detoxification enzymes activity and found that there was a positive correlation between the resistance to triazophos and the activity of cytochrome P450 with a correlation coefficient of 0.996.3.The relative expression levels of four resistant-related P450 genes in the five field populations and HN-Lab strain,including CYP324A12,CYP321F3,CYP9A68 and CYP6CV5,were detected with qRT-PCR.The results showed that CYP324A12,CYP321F3 and CYP9A68were all overexpressed in the all populations,especial for the XW19 population by 1.2-,3.4-,and 18.0-fold,respectively.In addition,the relative expression levels of CYP9A68 in the CZ19and TJ19 populations were also enhanced approximately 10.5-and 24.9-fold,respectively.4.Sel strain was obtained by treating two generations of cyantraniliprole with LD₂₅sublethal concentration using Sus strain as blank control with triplications for each treatment.Different transcripts of Sus and Sel strains were analyzed by three-generation full-length sequencing of transcriptome and there was 17.04 Gb Clean Data in total were obtained.550 of DETs were sreened out through screening,which of 327 transcripts were up-regulated and 223transcripts were down-regulated.GO functional analysis and KEGG analysis revealed that the DETs were significantly enriched in the metabolic pathway and 10 transcripts related to detoxification enzymes were screened for up-regulated expression.