Aphids are major crop pests that transmit more than half of all insect-vectored plant viruses responsible for high yield losses worldwide. Entomopathogenic fungi (EPF) are biological control agents mainly used by foliar application to control herbivores, including sap-sucking pests such as aphids. Their ability to colonize plant tissues and to interact with diverse plant pathogenic microorganisms have been reported. In our study, we evaluated the effectiveness of Beauveria bassiana ((Balsamo-Crivelli) Vuillemin) directly applied by contact or/and indirectly via endophytism in tobacco plants (Nicotiana tabacum L.) against the virus vector Myzus persicae (Sulzer) carrying the Potato leafroll virus (PLRV) or not. We found that both contact treatment and endophytic colonization of leaves significantly increased aphid mortality and decreased the fecundity rate when compared to control plants. In addition, on fungal-colonized leaves, viruliferous aphids were more negatively impacted than virus-free ones and nymph mortality was significantly higher than on fungal-free plants. Furthermore, we assessed PLRV transmission by M. persicae on tobacco plants inoculated with either B. bassiana or Metarhizium acridum ((Driver and Milner) JF Bischoff, Rehner, and Humber) as source or/and recipient plants. Myzus persicae was found to acquire and transmit PLRV regardless of the treatment. Nevertheless, the infection rate of endophytically colonized plants was lower at a seven-day incubation period and had increased to almost 100% after fifteen days. These results suggest that B. bassiana is effective against aphids, both by contact and via endophytism, and both B. bassiana and M. acridum delayed PLRV infection in tobacco.

中文翻译：

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内生病原真菌对昆虫桃蚜的适应性及其在烟草上传播PLRV的能力的直接和间接作用

蚜虫是主要的农作物害虫，其传播的所有昆虫媒介植物病毒中有一半以上是造成全球高产损失的原因。昆虫病原性真菌（EPF）是主要通过叶面施用来控制草食动物（包括树胶吸取的有害生物，如蚜虫）的生物防治剂。已经报道了它们在植物组织中定殖并与多种植物病原微生物相互作用的能力。在我们的研究中，我们评估了通过接触或间接内生作用直接在烟草植株（Nicotiana tabacum L.）中应用球孢白僵菌（（Balsamo-Crivelli）Vuillemin ）对病毒载体Myzus persicae的有效性。（Sulzer）是否携带马铃薯卷叶病毒（PLRV）。我们发现，与对照植物相比，叶片的接触处理和内生菌落显着提高了蚜虫死亡率并降低了繁殖力。此外，在真菌定殖的叶子上，有毒蚜虫比无病毒的蚜虫受到的负面影响更大，若虫死亡率显着高于无真菌的植物。此外，我们评估由PLRV传输桃蚜与任一接种烟草植物白僵菌或绿僵acridum（（驱动程序和米尔纳）JF Bischoff的，Rehner和亨伯）作为源和/或收件人的植物。桃蚜被发现不管治疗如何都能获取和传播PLRV。然而，在7天的培养期内，内生定植的植物的感染率较低，而在15天后，感染率已上升至几乎100％。这些结果表明，球孢杆菌通过接触和通过内生菌均有效地对抗蚜虫，并且球孢杆菌和a霉分支杆菌均延迟了烟草中的PLRV感染。