Identification Of Germplasm Resources Of 50 Strains Of Entomopathogenic Fungi And Screening Of Highly Virulent Strains Against Diamondback Moth(Plutella Xylostella L.)

Entomogenous fungi are important biocontrol agents which are well known for their role in the biological control of insect pests.The comprehensive information about germplasm resources of entomogenous fungi,and the ir classification of is the a prerequisite for development of any biological control.Diamondback moth is one of the important pests of cruciferous vegetables.This study reports the isolation,charac terization as well as virulence of 50 isolates,belonging to 14 different species,of entomopathogenic fungi against Plutella xylostella to screen out highly virulent fungal strains which can be used for the development of novel biopesticides.The major findings of this study are as follows:（1）Collection of soil or insect samples from different areas and habitats across Chinaresulted in the isolation of 50 fungal isolates.The morphological as well as genomic data（ITS,EF1-α,RPB1,RPB2 4 gene）based identification of these isolates showed that 50strains belonged to 7 genera and 14 species.The detailed description of identified isolates is as follows;isolates of Aspergillus fumigiatus:3 isolates;Beauveria bassiana:6 isolates;Cordyceps farinose:3 isolates,Cordyceps fumosorosea:2 isolates,Cordyceps tenuipes:one isolate;Paecilomyces lilacilinus:10 isolates,Paecilomyces marquandii:one isolate;Penicillium chrysogenum:5 isolates,Penicillium brasilianum:3 isolates;Metarhizium anisopliae:11 ioslates,Metarhizium robertsii:one isolate,Metarhizium brunneum:one strain,Metarhizium lepiotae:one isolate and Talaromyces verruculosus,2 isolates.（2）The newly isolated fungal strains were tested for their pathogenicity against 2^ndlarval instars of diamondback moth for preliminary screening of highly virulent strains.Metarhizium anisopliae isolate SM036,Cordyceps fumosorosea isolate SCAUDC L16,and Beauveria bassiana isolate SAUDCL10 were proved to be most virulent.These three strains were used for dose response assays against different life stages of diamondback moth.The median lethal concentration(LC₅₀)and median lethal time(LT₅₀)values were calculated through probit analysis.Based on LC₅₀ values Metarhizium anisopliae isolate SM036 was proved to be most virulent.（3）The fungal hyphae and crude toxin of Metarhizium anisopliae isolate SM036 were used to develop chitosan-based nanoparticles.The physical and biological properties of chitosan-based nanoparticles were observedthrough the X-ray diffraction（XRD）,Fourier transform infrared spectrum,field emission scanning electron microscopy（SEM）,high-resolution transmission electron microscopy（TEM）,atomic force microscope and zeta potential analysis.The findings of above analysis showed biologically active finished product.