AUTHOR=Wu Shengxin , Wu Jia , Wang Yun , Qu Yifei , He Yao , Wang Jingyan , Cheng Jianhui , Zhang Liqin , Cheng Chihang 

TITLE=Discovery of entomopathogenic fungi across geographical regions in southern China on pine sawyer beetle Monochamus alternatus and implication for multi-pathogen vectoring potential of this beetle

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1061520

DOI=10.3389/fpls.2022.1061520

ISSN=1664-462X

ABSTRACT=<p>Entomopathogen-based biocontrol is crucial for blocking the transmission of vector-borne diseases; however, few cross-latitudinal investigations of entomopathogens have been reported for vectors transmitting woody plant diseases in forest ecosystems. The pine sawyer beetle <italic>Monochamus alternatus</italic> is an important wood borer and a major vector transmitting pine wilt disease, facilitating invasion of the pinewood nematode <italic>Bursaphelenchus xylophilus</italic> (PWN) in China. Due to the limited geographical breadth of sampling regions, species diversity of fungal associates (especially entomopathogenic fungi) on <italic>M</italic>. <italic>alternatus</italic> adults and their potential ecological functions have been markedly underestimated. In this study, through traditional fungal isolation with morphological and molecular identification, 640 fungal strains (affiliated with 15 genera and 39 species) were isolated from 81 beetle cadavers covered by mycelia or those symptomatically alive across five regional populations of this pest in southern China. Multivariate analyses revealed significant differences in the fungal community composition among geographical populations of <italic>M</italic>. <italic>alternatus</italic>, presenting regionalized characteristics, whereas no significant differences were found in fungal composition between beetle genders or among body positions. Four region-representative fungi, namely, <italic>Lecanicillium attenuatum</italic> (Zhejiang), <italic>Aspergillus austwickii</italic> (Sichuan), <italic>Scopulariopsis alboflavescens</italic> (Fujian), and <italic>A</italic>. <italic>ruber</italic> (Guangxi), as well as the three fungal species <italic>Beauveria bassiana</italic>, <italic>Penicillium citrinum</italic>, and <italic>Trichoderma dorotheae</italic>, showed significantly stronger entomopathogenic activities than other fungi. Additionally, insect-parasitic entomopathogenic fungi (<italic>A</italic>. <italic>austwickii</italic>, <italic>B</italic>. <italic>bassiana</italic>, <italic>L</italic>. <italic>attenuatum</italic>, and <italic>S</italic>. <italic>alboflavescens</italic>) exhibited less to no obvious phytopathogenic activities on the host pine <italic>Pinus massoniana</italic>, whereas <italic>P</italic>. <italic>citrinum</italic>, <italic>Purpureocillium lilacinum</italic>, and certain species of <italic>Fusarium</italic> spp.—isolated from <italic>M</italic>. <italic>alternatus</italic> body surfaces—exhibited remarkably higher phytopathogenicity. Our results provide a broader view of the entomopathogenic fungal community on the vector beetle <italic>M</italic>. <italic>alternatus</italic>, some of which are reported for the first time on <italic>Monochamus</italic> spp. in China. Moreover, this beetle might be more highly-risk in pine forests than previously considered, as a potential multi-pathogen vector of both PWN and phytopathogenic fungi.</p>