Molecular Identification And Field Control Experiment Of Vegetables Thrips In Tianjin

Thrips,belonging to Thysanoptera,have file-sucking mouthparts.They like to suck juice from the young parts of plants,and most of them cluster on the back of leaves,causing aging,shrinkage,deformity and slow growth of the damaged parts.At the same time,they can spread many viruses such as tomato spotted wilt virus.With the increase of planting area in protected agriculture,thrips have become one of the most important vegetable pests in northern China,causing great economic losses for vegetable production.In recent years,the damage of vegetables thrips in Tianjin area has become more and more serious.In this paper,taking thrips as the research object,using mitochondrial DNA cytochrome c oxidase subunit I(mt DNA COⅠ)gene to explore thrips species in Tianjin,and identifying thrips species collected in Tianjin by extracting DNA,PCR amplification products,sequencing and other methods;Genetic differentiation,gene flow data analysis and mismatch analysis of different thrips sequences were carried out,and phylogenetic trees were constructed By designing specific primers for the main thrips identified in Tianjin,the identification is more time-saving and convenient;The efficacy of spirotetramat thiacloprid against thrips palmi was further tested in the field.The research results can clarify the genetic diversity and differentiation of different populations of thrips,further understand the diffusion law of thrips in different areas of Tianjin,and provide background basis for formulating scientific and reasonable control strategies for local thrips.The main results are as follows:1.The COⅠ gene sequences of 19 thrips populations were compared and analyzed by Genbank.it was found that there were 5 kinds of thrips in the samples collected in Tianjin,which were Thrips palmi,Frankliniella intonsa,Thrips tabaci and Megalurothrips usitatus.Thrips palmi have 11 populations,accounting for about 64%,which is the dominant population of thrips pests in Tianjin.Frankliniella intonsa have 4 populations,accounting for about 23%.Thrips tabaci have 3 populations,accounting for about 15%.Megalurothrips usitatus only occupy one population,accounting for about 5%.There are two kinds of thrips in cucumber in Ji Zhou.There are two thrips populations in Ning He Beans,which are mixed populations.2.The average contents of A,T,C and G in all sequences were33.70%,36.98%,16.12% and 13.2%,respectively,and the content of A+T was 70.68%,which showed obvious AT tendency.The study was collected11 thrips populations in Tianjin and sequenced their mt COⅠ genes,Thirty-seven variable sites were observed and 5 haplotypes were defined based on the 29 mitochondrial COⅠ sequences,which H1 had the highest frequency.By Genbank sequence comparison,it was found that all the 11 thrips populations were thrips palmi Population genetic differentiation,gene flow,and phylogenetic were analyzed by using software MEGA 10.0and Dna SP 5.10,find the measured low levels of genetic diversity and medium genetic differentiation,and high gene flow,but population genetic differentiation is small.the mismatch distribution curve had multiple peaks.The study indicatedthe population of Thrips Palmi in Tianjin were relatively stable in recent historical period,and has not experienced evident expansion;Seven sequences were obtained from four populations of Frankliniella intonsa in Tianjin,and six variation sites were detected.The average contents of A,T,C and G in all sequences were 33.66%,36.42%,18.18% and 13.72%,respectively,and the A+T content was 70.08%,which showed obvious AT tendency.Mismatch analysis of thrips showed a single peak,indicating that flowers in Tianjin had a single peak;Six sequences were obtained from three thrips tabaci populations in Tianjin,and five variation sites were detected.The average contents of A,T,C and G in all sequences were 31.12%,37.24%,17.51% and 14.11%,respectively,and the A+T content was 68.36%,which showed obvious AT tendency,The study indicatedthe population of Thrips tabaci in Tianjin were relatively stable in recent historical period,and has not experienced evident expansion.3.Based on the COⅠ sequence analysis of thrips in Tianjin,the sequences of thrips palmi,Frankliniella intonsa and Thrips tabaci were downloaded from NCBI,and the downloaded sequences were compared with all the sequences identified by us.Through comparison and analysis,we developed a primer system for rapid identification of field thrips palmi,Frankliniella intonsa and Thrips tabaci.This method is easy to operate,simple and effective,which is a good way to identify thrips and widely used.4.The results of field control of thrips palmi showed that:The control effect of 22% spirotetramat thiacloprid SC on thrips was only 61.89% on the third day after the first application,and it was over 77% on the seventh day after the first application,and rapidly increased to over 85% on the third day after the second application,and reached over 90% on the seventh day after the second application,which had significant advantages in the lasting period,and remained at 87% on the tenth day after the second application The harm of thrips palmi can be effectively controlled by spraying 22% spirotetramat thiacloprid SC with the dosage of active ingredients 108～144 g/ha,or the dosage of preparation 30～40 ml/ac,once every 7 days and twice in total.