Resistence Monitoring And Cloning And Quantitative Analysis Of SgAbd-1-like Gene In Frankliniella Occidentalis (Pergande)

Frankliniella occidentalis?Pergande?is an important invasive pest.Since its first identification in 2003 in China,F.occidentalis has spread to Beijing,Yunnan,Shandong,Xinjiang,Zhejiang,Guizhou,Jiangsu,Jilin,Ningxia,Xizang,and becomes one of the most threatening pests on horticultural crops.Generally the prevention and control of F.occidentalis is still dominated by using chemicals.However,due to the large-scale use of insecticides,with the short generation cycle,high reproductive ability and parthenogenesis,F.occidentalis can develop resistance to different pesticides rapidly.Resistance monitoring and resistance mechanisms studies are the foundation for resistance management.In the present study,the field resistance of F.occidentalis was monitored.The occurrence and dynamics of F.occidentalis in Lhasa,Tibet was investigated and the life table was established as well.The endocuticle structural glycoprotein?SgAbd-1-like?gene was chosen from the different expressed genes in the transcriptome data of the near isogenic lines of spinosad-susceptible?Ivf03?and resistant?NIL-R?F.occidentalis.The gene was cloned and the expression was compared between Ivf03 and NIL-R.The RNA interference system of F.occidentalis was established for further study of gene function.The following are the main results:1.Resistance monitoring of field populations of F.occidentalis to insecticidesAll of F.occidentalis populations developed different resistant levels to spinosad and spinetoram,and the resistance levels in changping,shunyi and tai'an were up to nearly100,000 times,so it was suggested to stop using them.The population in each area is sensitive to avermectin,thiamethoxam and cypermethrin,so it is recommended to use.The population in taian of Liaoning province and haidian of Beijing developed moderate resistance to bromoburionitrile and methylate respectively.2.Life table and field dynamics of Tibetan F.occidentalisLife tables for each sex were compiled,and the population dynamics of F.occidentalis on tomato plants in a solar greenhouse investigated using yellow sticky-card traps.The pre-adult developmental time of F.occidentalis was 12.54 d,and that of the second instar nymph was 5.62 d,accounting for 44.8%of the pre-adult period.The probability of eggs surviving to adulthood was 0.598.The average longevity of females was 15.18 d,whereas that of males was 9.64 d.The intrinsic rate of increase?r?and net reproductive rate?R₀?were 0.153/d and 22.817,respectively.Adult F.occidentalis were trapped all year round in the solar greenhouse.The population growth curve was of the"single peak"type,with the peak corresponding to the peak of adult emergence from mid-June to early August.3.Cloning and quantitative analysis of SgAbd-1-like geneThe total length of glycoprotein gene was 1016 bp,the open reading frame was 720bp,and the 5'UTR and 3'UTR were 89 bp and 207 bp,respectively,encoding 240 amino acids with no signal peptide.The predicted isoelectric point?pI?was 5.95,which is a partially acidic protein with a molecular weight?Mw?of 26.681 KDa,no transmembrane structure.Like most other species,the SgAbd-1-like gene of F.occidentalis contains a conserved region:chitin binding domain 4?Cht BD4??148-202?,which belongs to the CPR family RR-1 subclass.The results of fluorescence quantitative analysis showed that the expression level of the SgAbd-1-like gene was higher than that of Ivf03,but did not reach the significant level.There were significant differences in the expression levels at different ages in the same population.The expression level was the lowest at the first instar of nymph,and increased with the development of instar and reached the highest at adult stage.4.The RNA interference system of F.occidentalisThe synthetic dsRNA was mixed with 10%of pollen solution and was introduced into F.occidentalis by using feeding method,and the mRNA expression levels at different time after interference was determined by using real-time fluorescent quantitative analysis method.The results showed that the relative gene expression didn't differ significantly at different time when fed with dsEGFP and pollen solution?CK?.However,the relative expression of the gene decreased significantly after feeding the diet containing ds-RNA within 12h-24h,and the expression of the gene reached the lowest level after 24h of interference.The interference efficiency could reach more than 60%.