Resistance Monitoring Of Whitebacked Planthopper In Sichuan Province And Transcriptome Analysis Of Induction By Sulfoxaflor

The white-backed planthopper,Sogatella furcifera?Horváth??Hemiptera,Delphacidae?,is an insects around the world,which mainly feeds on rice,common wild rice,barnyard grass and so on.Due to overuse the chemicals,S.furcifera has produced the high resistance to some frequently-used insecticides.In this paper,the resistance levels of S.furcifera in eight areas of southern Sichuanand eastern Sichuanto chlorpyrifos,imidacloprid,thiamethoxam,buprofezin,pymetrozine,were monitored to grasp the resistance levels.Sulfoxaflor is a new sulfonimide amine pesticide developed by Dow AgroSciences,which activate the unique binding site in acetylcholine receptors,and lead to insectdeath ultimately.Moreover,the effects of sublethal concentrations(LC₁₀?LC₂₅)of sulfoxaflor onthe growth and reproduction of S.furcifera were researched.Transcriptome sequencing was used to analyze the induction effect of sulfoxaflor on the differentially expressedgenes?DEGs?related todetoxification and metabolism enzymes in the S.furcifera,and the DEGs cytochrome P450 genes were screened to further reveal the molecular mechanism of detoxification of S.furcifera to sulfoxaflor.The full text is summarized as follows:The resistance levels of eight local populations of S.furciferain Sichuan to the common insecticides chlorpyrifos,imidacloprid,thiamethoxam,buprofezin and pymetrozine were monitored using the rice seedling dippingin 2017-2018.The results showed that there were some differences in the sensitivity of these five insecticides among different geographical populations,and the resistance problem was more obvious.Among them,for chlorpyrifos,43.8%of the populations reached high level of resistance,with the highest?611.6-fold?of the Xuyong population?2017?,and the remaining 56.2%of the populations were moderate level of resistance.For imidacloprid,62.5%of the populations achieved high levels of resistance and 37.5%of the populations reached moderate levels of resistance.Only 3 populations of thiamethoxam achieved high levels of resistance,and the remaining 81.2%of the population showed moderate resistance.For pymetrozine,only 25%of the populations are at moderate levels of resistance,and the remaining 75%of the populations have achieved high levels of resistance.In addition,resistance to buprofezin was most prominent and all populations achieved high levels of resistance.The resistance mechanism of whitebacked planthopper to chlorpyrifos was studied by synergist experiment and enzyme activity assay.The results showed that the synergistic ratios of DEM and PBO to chlorpyrifos were 1.499 and 4.255 times,respectively,in the HN-Lab strains of whitebacked planthopper,and the synergistic ratio was 1.42 and 2.58 times in the field high resistant population?Xuyong population?;In addition,the multi-functional oxidase?MFO?and glutathione S-transferase?GST?activities of the high-resistance population of the white-backed planthopper were 2.29 and 1.48 times,respectively,compared with the HN-Lab strains.Meanwhile there was no significant difference in enzyme?CarE?activity.Therefore,multifunctional oxidase?MFO?and glutathione S-transferase?GST?may mediate the resistance of whitebacked planthopper to chlorpyrifos.According to the age-stage two-sex life tables theory,the life history data of all age-stage of S.furciferaof F0 and F1 generations treated with the LC₁₀,LC₂₅5 of sulfoxafloror blank treatment are recorded to analyze the differencesamong those treatments.The results indicated that thepre-adult,adult,female adult longevity and the total preoviposition period?TPOP?of S.furcifera treated with LC₁₀0 dose were all significantly prolonged compared to the control or the LC₂₅dose.The mean fecundity for LC₁₀ dose of sulfoxaflor?233.0 eggs/female?was significantly more than those in the control?168.1 eggs/female?and LC₂₅?140.8 eggs/female?.There were no differences in the intrinsic rate of increase?r?and finite rate of increase???of S.furcifera among the three treatments,whereas the net reproductive rate?R₀?of S.furcifera treated with LC₁₀0 dose was higher than those in the control or the LC₂₅5 dose.The mean generation time?T?for the LC₁₀ treatment was the longest?29.25 d?,followed by the treatments of LC₂₅?27.29 d?and the control?26.16 d?,and differed significantly from each other?P<0.05?.Therefore,S.furcifera had displayed stronger fertility under the LC₁₀ dose ofsulfoxaflor.The results of the synergist experiment and three metabolic detoxification enzyme activities showed that the enzymatic activity of MFO was significantly enhanced under the sublethal dose induction treatment of sulfoxaflor.Transcriptome sequencing was performed on the HN-Lab strain?M?and the HN-Sel strain?S?to screen the DEGs,with three biological replicates for each treatment.786 of DEGs were sreened out through genetic screening,which of 557 genes were clearly up-regulated and 229 genes were significantly down-regulated.All DEGs are enriched in the three kings of Ontologies data such as biological process,cellular component,and molecular function.Meanwhile,five cytochrome P450 genes related to the detoxification metabolism,including CYP6FD1,CYP4FD1,CYP6FD3,CYP6FD2 and CYP4FD2,were clearly up-regulated expression,and their functions in the adaptation of S.furcifera to sulfoxaflor would be further researched.In generel,chlorpyrifos should be avoided or used with caution or used alternately imidacloprid,thiamethoxam,buprofezin and pymetrozine to control S.furcifera in the field of Sichuan Province.The low sublethal dose of sulfoxaflor may promote the growth and development of the S.furcifera,and long-term continued use may cause the resistance risk.Moreover,P450 genes,including CYP6FD1?CYP4FD1?CYP6FD3?CYP6FD2 and CYP4FD2,could be involved in the metabolic detoxification of S.furcifera to sulfoxaflor.These finding provide theoretical assistance for Integrated Pest Management?IPM?strategy to control S.furcifera in the field.