Department of Entomology, Iowa State University, Ames, Iowa, United States of America.
United States Department of Agriculture, Northern Plains Agricultural Research Lab, Sidney, Montana, United States of America.
PLoS One. 2018 Mar 22;13(3):e0194815. doi: 10.1371/journal.pone.0194815. eCollection 2018.
Terrestrial plants can harbor endophytic fungi that may induce changes in plant physiology that in turn affect interactions with herbivorous insects. We evaluated whether the application of entomopathogenic fungi Beauveria bassiana and Metarhizium brunneum to soybean seeds could become endophytic and affect interactions with soybean aphid (Aphis glycines Matsumura). It was found that A. glycines population sizes increased on plants with M. brunneum (strain F52) seed inoculum, but no significant effects were shown with analogous treatments with B. bassiana (strain GHA). Fungi recovered from soybean plant tissues indicate that endophytism was established, and that B. bassiana was more prevalent. Metarhizium brunneum was only recovered from stems, but B. bassiana was recovered from stems and leaves. This work confirms that some entomopathogenic fungi can be endophytic in soybean, however, some of these fungi may have a negative effect on the plants by increasing susceptibility of soybean to A. glycines. We also used DNA sequence data to identify species of Metarhizium obtained from agricultural fields in Iowa. Phylogenetic analyses, based on DNA sequence data, found that all isolates were Metarhizium robertsii, which is consistent with past studies indicating a cosmopolitan distribution and wide host range for this species. These results are important for understanding the dynamics of implementing environmentally sustainable measures for the control of pest insects.
陆生植物可以携带内生真菌，这些真菌可能会引起植物生理变化，进而影响与草食性昆虫的相互作用。我们评估了将昆虫病原真菌绿僵菌和金龟子绿僵菌应用于大豆种子是否可以成为内生菌，并影响与大豆蚜虫（Aphis glycines Matsumura）的相互作用。结果发现，接种金龟子绿僵菌（菌株 F52）种子的植株上大豆蚜虫的种群数量增加，但类似的绿僵菌（菌株 GHA）处理则没有显著影响。从大豆植物组织中回收的真菌表明建立了内生关系，而且绿僵菌更为普遍。金龟子绿僵菌仅从茎部回收，但绿僵菌从茎和叶部回收。这项工作证实，一些昆虫病原真菌可以在大豆中内生，但其中一些真菌可能会通过增加大豆对大豆蚜虫的易感性而对植物产生负面影响。我们还利用 DNA 序列数据鉴定了从爱荷华州农田获得的金龟子属物种。基于 DNA 序列数据的系统发育分析发现，所有分离物均为罗伯茨绿僵菌，这与过去的研究一致，表明该物种具有世界性分布和广泛的宿主范围。这些结果对于理解实施环境可持续措施控制害虫昆虫的动态具有重要意义。
