Effects Of Tobacco Infested By Bemisia Tabaci (Gennadius) B Biotype On Myzus Persicae (Sulzer) And Physiological Mechanism Investigation

Bemisia tabaci(Gennadius) B biotype spread rapidly when it invades in China.It has been a key pest of various vegetables,cotton,tobacco and so on.At the present time,B.tabaci B biotype occurs in tobacco farmlands of Shandong province widely.We find that there has a few Myzus persicae(Sulzer) on tobacco infested by B.tabaci when investigating in farm.It indicates that B.tabaci was predomination in competing with M.persicae.However,there have no report about the influence of defense responses induced by B.tabaci on other sap-feeding insects at home and abroad currently.We start at farming phenomenon,choose tobacco as test materials,choose B.tabaci--tobacco-M.persicae as research system,study the effect of tobacco's defense response induced by B.tabaci on population growth,development and reproduction of M.persicae,major effect factors.We also investigate induced resistance mechanism initially.Investigating defense responses of tobacco to M.persicae induced by B.tabaci have important academic meaning for definiting competitive replacement ability of B.tabaci to M.persicae,showing competitive replacement mechanism of B.tabaci to M.persicae,and implementing sustainable control effectively.Major results as follows:(1) The effect of four tobacco varieties on development and reproduction of B.tabaci was studied.The results showed that K326,CF-965 were infested by B.tabaci easier.The developmental periods of B.tabaci were shorter than other tobacco varieties'.Survivorship and the number of eggs deposited by B.tabaci were higher than other tobacco varieties'. NC-82,NC-89 were more resistant to B.tabaci.The developmental periods of B.tabaci feeding on them were longer,survivorship were lower,and the fecundities were lower.They went against development and reproduction of B.tabaci.(2) The effect of B.tabaci on host plant preference of M.persicae was studied with two different methods.The results showed that M.persicae adults liked to choose the plant without B.tabaci infested,compared to host plant infested by B.tabaci.And for leaves depart from host plant,tobacco leaves of different position had different effect on host plant preference of M.persicae.Compared to respective control leaves,damaged leaves had significant repellence on M.persicae,but,white-vein leaves and unexpanded leaves had significant attraction to M.persicae. (3) Tobacco infested by B.tabaci had significant inhibition on population growth, development and reproduction of M.persicae.Mix developmental stages and nymphs of B.tabaci infested tobacco had significant influence on mortality of first generation of M.persicae.They were higher 23.8%,30.0%than that of M.persicae fed on the plant without B.tabaci infested.Compared to control plants,the population growth rate of second generation,third generation reduced 55.5%,49.2%;87.9%,79.6%,respectively.The population growth of M.persicae was inhibited significantly.The effect of B.tabaci damaged leaves and white-vein leaves on development and reproduction of M.persicae was studied with clip-cage.The results showed that the white-vein leaves infested by B.tabaci had significant detrimental influence.Compared to leaves of same position on control plant,the mortality increased 46.6%when switching on M.persicae for 8 days,developmental times prolonged 0.9 days,mean relative growth rate reduced 6.5%,and average fecundity decreased 5.7 per female.The development and reproduction of M.persicae was inhibited significantly. But,the damaged leaves had no significant negative influence on development and reproduction of M.persicae.(4) Major effect factors of tobacco defense responses to M.persicae induced by B.tabaci were studied.The results indicated that B.tabaci nymphs were major factor which induced defenses responses to M.persicae.Defense responses of tobacco to M.persicae could not induced by B.tabaci infested 9 days with 500 adults per plant.The effect of infested density of B.tabaci(0-1/cm²,2-3/cm²,5-6/cm²,11-12/cm²) on M.persicae was studied.The results showed that tobacco infested by B.tabaci nymphs with 0-1/cm² had no harmful effect on M.persicae.Tobacco defenses to M.persicae began to expression when density reached to 2-3/cm².When density reached to 5-6/cm²,it was expressed the most significantly.The mortality was the highest,56.8%higher than control. When density reached to 11-12/cm²,the negative effect on M.persicae was lower than prior infested density.The influence of infested time of B.tabaci nymphs with 9-10/cm²(1d,5d,10d,15d) on M.persicae was studied.Along with growing of B.tabaci nymphs and prolonging of infested time,the influence of defense responses to M.persicae began to strengthen and then weak. B.tabaci nymphs infested 1 day had no significant effect on M.persicae.Induced defense responses of tobacco began to express when nymphs infested 5 days,the mortality of M.persicae feeding on white-vein leaves was 36.1%higher than control plant.10 days infested by B.tabaci nymphs resulted in strong expression of defenses to M.persicae.The mortality of M.persicae fed on white-vein was the highest,72.8%higher than control plants. Mean relative growth rate was the lowest.B.tabaci nymphs reached to subnymph periods when they infested 15 days.The effect on M.persicae began to reduce compared to that of 10 days infested by B.tabaci nymphs,the mortality was 58.9%higher than contrast plant.(5) Tobacco's defense response induced by B.tabaci to M.persicae had temporal and spatial effect.We studied the effect of defense responses on mortality,population growth rate, and fecundity of M.persicae with clip-cage.The results showed that among leaves of four position infested by B.tabaci,white-vein leaves had significant influence on development of M.persicae.The sequence of effect on mortality,development and reproduction of M.persicae was white-vein leaves>middle leaves>unexpanded leaves>damaged leaves.It proved that defense responses of tobacco to M.persicae can transmit spatially within tobacco.We wiped off nymphs when B.tabaci nymphs developed to 3_rd instar and then switched on M.persicae.There had significant influence on M.persicae after wiped off B.tabaci nymphs for 15 days.Mortality and population growth rate of M.persicae had significant difference between treated and control plants.Along with duration prolonged,the influence began to retard.After 20 days,the negative influence disappeared.It suggested that the duration of induced resistance was around 15 days.(6) We determinated major nutritional index in tobacco damaged by B.tabaci.The results indicated that there had negative correlation between soluble sugar,soluble protein content and mortality of M.persicae.Total content of amino acids in tobacco infested by B.tabaci increased.Content of Asp deduced,content of Pro,Ala,Gly,Val,Phe,Lys and so on increased. The total protein content of tobacco damaged by B.tabaci also had some relativity with tobacco's resistance to M.persicae.