AUTHOR=Zhao Jie , Chen Yuxi , Keyhani Nemat O. , Wang Cong , Li Yichen , Pu Huili , Li Jincheng , Liu Sen , Lai Pengyu , Zhu Mengjia , He Xueyou , Cai Shouping , Guan Xiayu , Qiu Junzhi 

TITLE=Isolation of a highly virulent Metarhizium strain targeting the tea pest, Ectropis obliqua

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1164511

DOI=10.3389/fmicb.2023.1164511

ISSN=1664-302X

ABSTRACT=Larvae of the moth, Ectropis obliqua Prout (Geometridae, Lepidoptera) are one of the most destructive insect pests of tea in China. To identify novel E. obliqua biological control agents, eleven isolates corresponding to ten different species of Metarhizium were identified according to morphological and molecular analyses from soil and/or insect cadavers found on tea plants and/or in the surrounding soil sampled from eight different regions within the Fujian province, China. Four species of Metarhizium including M. clavatum, M. indigoticum, M. pemphigi and M. phasmatodeae were documented for the first time in China, and the other species were identified as M. anisopliae, M. brunneum, M. lepidiotae, M. majus, M. pinghaense, and M. robertsii. Insect bioassays of the eleven isolates of Metarhizium revealed significant variation in the efficacy of each isolate to infect and kill E. obliqua. Metarhizium pingshaense (MaFZ-13) showed the highest virulence reaching a host target mortality rate of 93% in laboratory bioassays. The median lethal concentration (LC50) and median lethal time (LT50) values of M. pingshaense MaFZ-13 were 9.6×104 conidia/mL and 4.8 days, respectively. Greenhouse experiments and a time-dose-mortality (TDM) model were used to further evaluate and confirm the fungal pathogenic potential of M. pingshaense MaFZ-13 against E. obliqua larvae. These data indicate that the newly isolated M. pingshaense MaFZ-13 strain represents a highly virulent isolate for the control of E. obliqua larvae.