Research On Fungal Biocontrol Agents Of The Hyphomycetes Against Green Peach Aphid Myzus Persicae(Sulzer)

The entomopathogenic fungi of the Hyphomycetes have a significant effect forcontrolling disease and insect pests of forestry economic plants. As one of them,Beauveria bassiana（Balsamo）Vuillemin shows a good quality against suckingmouthparts pests （such as aphids,whitefly,ect） and plays a great role in the aphid harmwordwide. Chemical pesticides can effectively control tobacco aphids, while bring theproblem of pesticide residue meanwhile. Microbial pesticides have the merit of nopollution on environment and no harm for the untarget insects, which share an increasein IPM system year by year.This thesis determined the best formula of Wettable powderand Suspended emulsions of the spore Beauveria bassiana conidium,through screeninga series of auxiliaries by good biocompatibility with Beauveria bassiana conidium.After the biological assay indoor, research about controlling green peach aphid MyzusPersicae in yishui region in Shandong was revealed. The research studied the storagestability of the two preparation as well as reaveald at4℃and25℃, respectively. Themain research results as follows:1、Prescription screening of Wettable powder and Suspended emulsion and qualityindex determinationThe conidium of Beauveria bassiana was producted by the liquid-solid two-phasefermentation, and spores content is1.20×1011/g, the conidial viability is above97%after the vacuum freezing drying. Through the carrier, wetting dispersant, emulsifier,Uv protectants, suspension stabilizer screening, we determined the best formula ofSuspended Emulsion and Wettable powder of Beauveria bassiana conidium. Wettablepowder: effective component10%conidium, wetting agent3%MF-5, dispersant3%WorwetD-425, Uv protectants0.3%ascorbic acid, carrier85.7%diatomite. Suspendedemulsion: liquid paraffin as solvent oil, effective component10%conidium, emulsifier1%TXP-10, suspension stabilizer making0.3%CMC-Na, Uv protectants0.3%Vc.Wettable powder initial including spores content was1.20×10¹⁰/g, the spore viabilitywas93.28%, the time of wettability was89.2s, quality suspended rate was62.22%, thespore suspension rate was95.11%, the fineness of98.5%（through the200screeningmesh product）, water content was1.5%, and the pH was6.80. The spores content ofSuspension emulsion was1.20×10¹⁰/mL, spore viability was94.44%.2、The biological assay indoor of Wettable powder and Suspended emulsion againstgreen peach aphid Myzus Persicae We use homemade samples controlling green peach aphid Myzus Persicae inlaboratory conditions, with the same group as control, the results as follows: The lethaleffect of Suspension emulsion on green peach aphid Myzus Persicae is stronger thanWettable powder under the same concentration. The mortality rate of SE group is themaximum in the test, was66.7%after treated with1.20×107/mL after the spraying7day;while the WP group with1.20×105/mL is the minimum, was only49.10%. Data from alltreatment was analyzed through SPSS statistics17.0undertake Regression analysis, theresults shown that LT50value of different treatment was inversely proportional to thespraying concentration. The LT50value of SE3.538d with1.20×107/mL is theminimum in all treatmentï¼›The LT50value of the spore suspension with1.20×105/mL isthe maximum，while the LT50value of SE with1.20×105/mL is greater than the LT50value of WP with1.20×106/mL.3、The research on control effect against green peach aphid Myzus Persicae aboutWettable powder and Suspended emulsion at yishui, ShandongTest was conducted in September,2011in Yishui tobacco fields, Shandongprovince. The test design was two kinds of agents used alone, two agents mixed withimidacloprid respectively, imidacloprid used alone, distilled water as negative control.The results showed that the control effect of two agents on aphids was significantlylower than the chemical pesticide imidacloprid in the first3days, the control effect upto96.4%on the7day from begining，be similar to imidacloprid, Wettable powdercontrol effect for aphids aslo up to96%on the9th day after spraying; And the controleffect of two preparation mixed with imidacloprid between chemical pesticides usedalone and two preparations used alone, which explain that microbial pesticide have aslower efficacy, but the control effect will be equal to chemical pesticide eventually.4、The storage stability of Wettable powder and Suspended emulsionWe studied the storage stability of homemade Wettable powder and Suspendedemulsions with conidium of Beauveria bassiana for180d at4℃and25℃. Determinethe initial quality indicators of the two preparation before storage, and measure onceevery15d during the storage, the results show that:4℃will be in favour of maintainingthe preparation spores vitality than25℃. After180d storage of two agents, the sporesvitality of two preparations at25℃was about3.0%lower than at4℃compared withinitial respectively. Comparied to Wettable powder, Suspension emulsion seems morestable. After180d, the spores vitality of Suspension emulsion with Beauveria bassianaconidium was86.91%at25℃,7.53%lower than initial spore vitality; while the sporesvitality of Wettable powder was8.99%lower compared with the initial. Predictably, low temperature is more advantageous to the storage of the preparation; Spores isolatedfrom the air, to some extent, can make the spores in dormant period, which have greatsignificance on the extention of the storage of the preparations.