Tenebrio molitor-mediated entomopathogenic fungal library construction for pest management

Entomopathogenic fungi are soil-dwelling microorganisms that infect host insects, and some have been used as biological control agents. Construction of an entomopathogenic fungal library provides a strong platform for the development of highly effective biopesticides, but the traditional method using antibiotic media has low isolation efficiency. Herein, to increase the efficiency of isolation, a Tenebrio molitor pathogenicity-based fungal collection method was used for the construction of a library. The isolation efficiency using the T. molitor larvae-based pathogenicity assay was 55.4%, which was significantly higher than the method of antibiotic medium with dodine (6.0%). We named it the Jeonbuk (Chonbuk) National University Entomopathogenic Fungi (JEF) library. It consisted of 279 isolates belonging to 12 genera and 29 species. Main features of the species-representative 15 isolates were characterized in terms of morphology, virulence, conidiogenesis, thermotolerance and production of biologically active materials such as virulence-related enzymes. Some of the species-representative isolates showed higher virulence against T. molitor, Riptortus pedestris and Plutella xylostella in laboratory conditions. The production of enzymes such as chitinase, Pr1 protease and lipase all related to pathogenesis in LB medium was higher than in the SDB and PDB media. In the thermotolerance assay, a Purpureocillium lilacinum isolate showed higher thermotolerance than other isolates. This work reports an efficient library method using T. molitor for building a library for development of fungal biopesticides for pest management.