Studuy On Biological Characteristics Of Beauveria Bassianaand Its Pathogenicity To Aphid

Aphids are common pests in garden plants and about 40 different aphid species were reported on garden plants,including Aphis gossypii Glover,A.citricola Van der Goot,Myzus persicae,Macrosiphum rosivorum,Macrosiphniella sanborni,Tinocallis kahawaluokalani,Cinara pinitab?Laeformis,Chaitophorus populialbae and Aphis glycines,and so on.Aphids make not only direct damage,but indirect damage to plants by virus transmission.Some winter host plants of aphids?ex.Rhamnus,Medicago?are also important ornamental garden plants.So far as we known,although chemical pesticides had brought many problems just like pesticides residue,pest resistance and environmental pollution,it was still commonly used for aphids control.Beauveria bassiana,as an entomogenous fungi,had been widely used for pests control for several decades,which could be a potential control way aphids efficient control and keep species diversity,ecological balance,protect garden plants,protect natural enemies,reduce loss.However,very few research was reported for aphid control on garden plants by using B.bassiana.In this study,15 wild strains of Beauveria bassiana were collected and isolated from different areas in Jilin province and was bioassayed on legumes aphids indoor.Study on the biological characteristics was carried out,including colony morphology,spores production,spores germination rate,and colony growth speed.Biochemistry characteristics,including extracellular protease activities and Pr1 protease activity,were studied and analyzed.Different concentrations of sporozoite particles were prepared for toxicity test of 15 strains against Aphis glycines.ITS sequences were analyzed for all the 15 strains.The results were as follows:I.It showed that the type I style strains exhibited more abundant spores production,higher germination rate,and more quick colony growth.II.Biochemistry characteristics study indicated that there was significant difference of Pr1protease activity among different strains,in which strains D4-2-1 and DA3 showed higher activity than those of others,while not for extracellular protease activities.III.It was obvious that all 15 strains of B.bassiana showed toxicity against aphids of legumes.It showed that the higher spores concentration,the higher death rate.Spores concentration of 1×10⁸/mL gave a very good infection result.It showed that S14-X-1 is the most virulent strain with lowest LT₅₀0 for 153.3 hours,highest infection rate for 41.2%and Lg(LC₅₀)for 9.3?condia/mL?as well..IV.The ITS sequence analysis of all 15 strains of fungus indicated a consensus homology,most of them showed a 100%identities,excepte for strain 14?YSH7?for 96%identities.There was no significant difference among ITS sequences of all test fungal strains,which indicated ITS gene was not a good molecular maker for phylogenetic analysis of among Beauveria bassiana and new molecular markers or specific genes should be used for its phylogenetic analysis..In conculsion,three strains?D4-2-1,S14-X-1,CHL20?were potential for aphids field control of the legumes garden plants based on all the data from morphological,biochemical and bioassay analysis.