Isolation and identification of pathogenic fungus from a strain of Suana divisa and determination of range of its hosts

【Objective】To clarify the taxonomy and biocontrol potential of an entomogenous fungal strain isolated from Suana divisa（Moore），so as to provide theoretical basis for enriching entomogenous fungal resources and biological prevention and control.【Method】 Pathogens were isolated and purified from a diseased S.divisa（Moore）by regular tissue isolation method.After pathogenicity identification，taxonomy of the pathogen was identified through morphological observation and constructing phylogenetic tree based on rDNA-ITS，EF1-α and β-tublin gene sequences.Biological characteristics of the fungi were determined by mycelial growth and spore production under different environmental conditions.The host range of the fungi was determined by spraying the tested insects with the pathogen spore solution.The spores of the fungi were prepared into spore suspension with different concentration gradients to treat Locusta migratoria manilensis （Meyen），Dendrolimus punctatus（Walker）and Solenopsis invicta（Buren）.The field control experiment was carried out with powder produced by the fungi to investigate the control effect.【Result】 An entomogenous fungus strain DMC01 was isolated from S.divisa（Moore）.The results of pathogenicity test showed that strain DMC01 was disease pathogenic fungus of S.divisa（Moore），and it was identified as Isaria javanica through morphological characteristics analysis and molecular identification.Full light，temperature of 26℃，pH of 7，sucrose as carbon source and yeast extract and beefextract as nitrogen sources were the most suitable for strain DMC01 mycelial growth and spore production.The preliminary determination of host range of strain DMC01 showed that it could parasitize 15 species of pests in 5 orders and under the treatment of 1×108 conidia/mL，the calibrated mortality of the 4^th instar larvae of L.migratoria manilensis（Meyen），D.punctatus（Walker）and S.invicta（Buren）reached 100.00%.The results of field control experiment showed that the average control effectiveness of DMC01 strain powder on all pests insects on eucalyptus forest was 51.9% in 2020 and 79.1% in 2021.【Conclusion】 I.javanica strain DMC01 isolated from a naturally dead S.divisa（Moore）has high pathogenicity to eucalyptus forest pests and is potential to be a biocontrol agent.