Molecular Assessment Natural Enemy Control Function On The Bemisia Tabaci On Different Host Plants

Bemisia tabaci are a kind of important crop pests in the field. The protection and using of natural enemy insects is the main measures for sustainable prevention and control of B.tabaci. In the agro-ecosystem of north China, Encarsia Sophia(Girault & Dodd), Eretmocerus hayati(Zolnerowich and Rose), Encarsia formosa(Gahan) are three important parasitoid enemies of B.tabaci. Propyleajaponica, Harmonia axyridis(Pallas), Chryhopa, Misumenopos tricuspidata(Fahricius), Hylyphantes graminicola are important predatory natural enemy of B.tabaci. It is the vital foundation of bio-control to make precise assessment of the control effects of natural enemies. DNA barcoding analysis technology has offered a vital assistance of technique for the study on pest-control effects of the natural enemies in the natural environment.In the research of agro-ecosystem of north China, we researched three parasitoids of B.tabaci in five plants, including of cotton, eggplant, tomato, sunflower, sweet potato. Studying and analysis spatial distribution regularities of nymph and adult of B.tabaci in the five host plants.The study shows that it is obviously difference which seasonal population dynamics and the vertical distribution rule of B.tabaci nymph and adult in host plants.We designed the species-specific primers of E.Sophia, E.hayati, E.formosa, the sequence size are 480 bp, 328 bp, 394 bp respectively. The DNA and plasmid concentration detection limit of the primers respectively are 0.057 ng/u L,0.078 ng/u L,0.341ng/u L, 4.7×10-5ng/u L,6.6 ×10-3ng/u L,6.0 ×10-4ng/u L.The multiplex PCR of the sequence size are 287 bp, 186 bp, 394 bp. The DNA and plasmid concentration detection limit of the primers respectively are 2.2×10-5ng/u L, 0.325ng/u L.The specificity of the primers was detected against the DNA of 58 species occurring in the same habitat. There are two amplification product of targets species in the results of Species-Specific-COI PCR amplification. It apparently indicated that the pairs of parasitoid primers had powerful specificity.Testing the parasitoids DNA of E.formosa, E.Sophia and E.hayati detectability success(DS50)in the predatory enemies of Propylea japonica, Harmonia axyridis, Misumenopos tricuspidata, Chrysopa perla, Hylyphantes graminicola. We set seven digestion period: 0 h, 4 h, 8 h, 12 h, 16 h, 20 h and 24 h,and found the value of DS50 varied among 3.30 h to 8.55 h. The detection of field samples on the basic of parasitic rate of Bemisia tabaci in different hosts.The result shows that the parasitization rates of E.formosa, E.Sophia, E. hayati are 8.01%, 0.174%, 2.09%.Studying the IGP of predatory natural enemies with E.formosa, E.Sophia and E. hayati. The nine groups of predator to prey including P.japonica × E.formosa, H.axyridis×E.formosa, C.perla × E. formosa, M.tricuspidata × E.formosa, P. japonica × E. hayati, H.axyridis × E.hayati, H.graminicola × E.hayati, H.axyridis × E.Sophia, M. tricuspidata × E.Sophia. We detect out 56 nymphs of B.tabaci in predatory natural enemies, and the parasite are 13. The studying suggest that the predation rate of groups are different. The predation rate respectively are 1.0%, 1.48%, 0.97%, 0.53%, 1.0%, 0.74%, 16.7%, 0.37%, 0.53%.The reviesed date are 0.33%, 0.40%, 0.35%, 0.18%, 0.46%, 0.21%, 8.05%, 0.13%, 0.24%. Using the molecular detecting, the current research work proved that there was being Intraguild predation(IGP) among predatory enemy of B.tabaci in the field.