Ecological Fitness Of Bemisia Tabaci On Different Tobacco Varieties

In recent years Bemisia tabaci(Gennadius)did many harm to tobacco in our country.Selecting pest-resistant plant strains turns out to be the best way to kill B.tabaci.In order to provide a theoretical promotion and production for the basis of tobacco resistant varieties,20 tobacco varieties were chosen to study the fitness of B.tabaci and the resistance mechanisms to Q-biotype B.tabaci.The main results and conclusions were summarized as follows:1.The identification for the biotype of B.tabaci: utilizingBy gene COImtDNA sequences as a marker to identify biotype of B.tabaci on the tobacco crops in qingdao in Shangdong.The result showed that the COI gene fragment(853 bp)of this population and Q-biotype B.tabaci with accession number HQ198746.1,EF080823.1,FJ188574.1 had more than 99% homology.Therefore,the biotype of this population whitefly is Q-biotype.2.Selectivity of the adult of Q-biotype B.tabaci to different tobacco varieties: In this thesis,the whitefly selectivity on 20 tobacco varieties were studied.We could understand that the selectivity were significantly which.varietiestobaccodifferent on After infestation h,72 48,24,for the number of Q-biotype B.tabaci adults was large on While,MY57'' and MY9'' the number of Q-biotype B.tabaci was small,YY97''on ‘V2',‘YY100',‘changbohuang';After infestation for seventy-two hours,the number of eggs was large 239.25,they wereand,MY57'' and MY9''on 226.75 eggs per plant.It was small on ‘YY97',‘V2',‘YY100',‘CBH' and it was 66.75?74.75?77.25?77.50 eggs per plant.3.Effects of different tobacco varieties to the developmental of Q-biotype B.tabaci: The development longevity rate,survival duration,at thefecundity and adult stage of Q-biotype B.tabaci on the different tobacco varieties were researched.We could know that the adaptability of Q-biotype B.tabaci were significantly affected by the tobacco varieties.The larval development duration was longest for 21.31 days on ‘MY9',and it was shortest for 19.27 days on ‘YY97'.The whitefly survival on ‘MY9',‘MY57' was higher for 77%,and it was,YY100'',V2'',YY97''on less ‘CBH' for 54%.The longevity,fecundity and adaptability of next generation of Q-biotype B.tabaci onstronger were YY100'',V2'',YY97''on than MY57'',MY9'' and ‘CBH'.4.The resistance mechanisms of tobacco varieties to Q-biotype B.tabaci: According to the selectivity and adaptability of B.tabaci on the different tobacco varieties,6 tobacco varieties were selected to study the resistant mechanism of the whitefly to tobacco.We could see that the contents of soluble protein in fresh leaves of different tobacco varieties had no obvious differences,but the trichome density,pH and the contents of soluble protein and chlorophyll had some differences.Correlation analysis results showed that the relativity of trichome density with the number of B.tabaci was extremely positive significant,and the relativity of the content of soluble protein with the number of B.tabaci was positive correlated,yet with no significant level.Whilst the relativity of pH and the chlorophyll content in fresh tobacco leaves with the number of B.tabaci were significantly negative correlated,and most of them with extremely significant level.We conclude that the content of soluble protein has less considerable effects on the resistance of tobacco variety to B.tabaci,while the trichome density,pH and the contents of chlorophyll have more considerable effects.