Suppression of Rice Planthopper Populations by the Entomopathogenic Fungus Metarhizium anisopliae without Affecting the Rice Microbiota

摘要

Entomopathogenic fungi can regulate insect populations and function as crucial biological control agents against insect pests, but their impacts on nontarget microorganisms are poorly understood. In this study, we investigated the potential of the fungal strain Metarhizium anisopliae CQMa421 to control rice planthoppers under field conditions and its effects on rice microbiota. This fungus suppressed rice planthoppers during this period, and its control efficiency was more than 60 7 days after application and did not significantly differ from that of the chemical treatment except in 2019. Both treatments showed a smaller population of rice planthoppers than the controls. After application, M. anisopliae was maintained on rice plants for approximately 14 days, showing a decreasing trend over time. Furthermore, the results showed that the bacterial and fungal richness (operational taxonomic units) and diversity (Shannon index) did not significantly differ between the fungal treatment and the controls after application. The major bacterial taxa of Proteobacteria (including Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria), Actinobacteria, Bacteroidetes, and Cyanobacteria accounted for more than 80 of the bacterial community after fungal application, and the major fungal taxa Ascomycota (including Eurotiomycetes, Dothideomycetes, and Sordariomycetes) and Basidiomycota (including Ustilaginomycetes) represented more than 90 of the fungal community. However, the microbial communities of the rice phyllosphere did not significantly change after entomopathogenic-agent application, indicating that the indigenous microbial communities may adapt to fungal insecticide application. Taken together, the results suggest that this fungal agent has good potential for rice planthopper control with no substantial effects on rice microbial communities.