Effects Of Tobacco Infested By Bemisia Tabaci B-biotype On Interspecific Competition And Detoxification Metabolism Between B, Tabaci And Trialeurodes Vaporariorum

Bemisia tabaci biotype-B is one of the important agricultural pests worldwide and candisplace an indigenous non-B population B. tabaci. We chose B. tabaci-tobacco-T.vaporariorum as a research system, as based on B. tabaci has interspecific competitiveadvantage to T. vaporariorum, we further proved that the effect of tobacco defense responseinduced by B. tabaci play a very important role in the interspecific competitive advantage to T.vaporariorum. We explored the effect of tobacco defense response induced by B. tabaci onplant growth and secondary metabolites. We studied the effect of tobacco’s defense responseinduced by B. tabaci and T. vaporariorum, respectively, on development and reproduction ofT. vaporariorum and B. tabaci. Meanwhile, we explored the difference of detoxificationmetaboilsm adaptability of the two insects to defense response of tobacco induced by B.tabaci. This research had important academic meaning for showing competitive replacementmechanism of B. tabaci to T. vaporariorum, and implementing sustainable control effectively.Major results as follows:1. B. tabaci has obvious interspecific competition advatanges to T. vaporariorum ontobacco and tobacco defense induced by B. tabaci play a very important role in theseadvantages.(1) The competition between B. tabaci and T. vaporariorum on tobacco was studied. Theresults showed that the T. vaporariorum numbers in mixed populations were only38.2%ofisolated populations numbers, were only24.4%of the sum of mixed populations. B. tabacinumbers in mixed populations were75.6%of the sum of mixed populations. T. vaporariorumprefer feeding on the upper leaves, bu B. tabaci was like to feeding on the middle leaves. Inthe upper leaves, the livability of T. vaporariorum nymphs in mixed populations wasdecreased by30.4%compared with the livability of nymphs of isolated populations.However, the livability of B. tabaci was no significantly changes. It indicated that the tobaccodefense response induced by whitefly to T. vaporariorum, but had no effects to B. tabaci.(2) We determined that the effect of tobacco plants infested by B. tabaci on B. tabaci andT. vaporariorum. The results showed that the tobacco plants after infested by B. tabacibiotype B had negative effects on the growth, development and fecundity of T. vaporariorum,but had no significantly effects of B. tabaci. After feeding on the systematic leaves of tobaccoinfested by B. tabaci, the average livability of T. vaporariorum was decreased38.6%, thedevelopmental periods was prolong2.6d, and the5days and10days fecundity decreased 46.3%and30.1%, respectively, compared with those in the control. The tobacco plants afterinfested by T. vaporariorum had no effects on growth, development and fecundity of T.vaporariorum and B. tabaci. The results indicated that the interspecific competition betweenT. vaporariorum and B. tabaci exist obvious asymmetry that was one of the reason of B.tabaci competitive displacement advantages to T. vaporariorum.2. The difference of tobacco growth after feeding by B. tabaci and T. vaporariorum,respectively, based on the whitefly population density of reached plant induce defense. Thetaobacco plants infested by B. tabaci had negative effects on plant growth, but had no effectson plant growth after feeding by T. vaporariorum. The plant height was decreased6.9cm,and the1stinternode and2ndinternode of tobacco preinfested by B. tabaci were decreased by55.4%and47.0%, respectively. The leaf number of tobacco plants preinfested by B. tabaciwas decreased by13.0%, and the dry weight per unit area was decreased by47.6%comparedwith control. B. tabaci feeding can induce chemical defense responses in plants, B. tabaci-elicited declines in growth may result from the re-allocation of resources from growth todefense.3. The contents of chlorogenic acid and rutin of systematic leaves preinfested by B.tabaci were increased by3.95-and3.93-fold compared with control. The contents of phenoliccompound of damaged leaves were no change. Our results showed that the increasedchlorogenic acid and rutin were correlation with plant defense to T. vaporariorum.4. After feeding on the tobacco systematic leaves preinfested by B. tabaci, the activitiesof CarE、GST and the CyP450of B. tabaci adults were increased. The activities of CarE andthe CyP450content of B. tabaci were increased by1.15-1.68and1.48-2.60fold from6h to48h, respectively. Through esterase isozyme electrophoresis and determine the activity ofCyP450oxygen demethylase, we also found that the activities with two enzymes of B. tabaciadult were increased. The nymphs had the same result, but the activities of CarE and GSTwere increased in1stand2ndinstar, the activity of CyP450oxygen demethylase was onlyincreased in1stinstar. However, the activities with three enzymes in adults of T.vaporariorum were inhibited. The activity of CarE significantly inhibited except fo that atr48h, and the maximum activity was decreased by0.58fold compared with those in thecontrol. The content of CyP450was significantly inhibited by0.4-0.63fold from6h to72h.Through esterase isozyme electrophoresis and determine the activity of CyP450oxygendemethylase, we also found that the activities of two enzymes in adults of T. vaporariorumwere significantly inhibited. The enzymes activities with three were inhibited in1stinstar, butthe activity of CarE was the most inhibited compared with other enzyme activity. After feeding on the damaged leaves of tobacco infested by B. tabaci, the activity of detoxifyingenzymes in adults and nymphs of T. vaporariorum and B. tabaci have no significantlychange. The detoxifying enzyme activity changes of two insects have significantlydifferences, and it might play an important role in B. tabaci displacing T. vaporariorum.