Photorhabdus luminescens is an entomopathogenic rod-shaped bacterium infected with insect nematodes of the Heterorhabditidae family. It kills insects through the secretion of high molecular weight toxin complexes. In this study, Plutella xylostella larvae were orally administered P. luminescens for bioassay. After incubation in Luria-Bertani (LB) medium for a sufficiently long period, the mortality rates of P. xylostella observed after diluting the fermentation broth 50 times and diluting the supernatant 5 times were 18.89% and 91.11%, respectively. Retentates measuring more than 70 kDa showed 88% mortality after ultrafiltration (UF) membrane treatment. Thus, the supernatant of P. luminescens had insecticidal activity, and the main insecticidal toxin complexes had a molecular weight exceeding 70 kDa. The L9 (34) Taguchi orthogonal experimental optimized medium mode-predicted insecticidal activity levels were 84% and 119% in the 50-fold diluted fermentation broth and 5-fold diluted supernatant, respectively. Moreover, the insecticidal activity was improved to 92.2% in the 100-fold diluted fermentation broth and to 97.8% in the 10-fold diluted supernatant in the experiments. All combinations tested showed clear indications of lethality, including swelling, vesicle formation, cytoplasm vacuolization, and brush border membrane lysis. Thus, these results promote the use of P. luminescens 0805-P2R as a potent biopesticide to effectively control P. xylostella.

中文翻译：

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夜光杆菌0805-P2R对小菜蛾的杀虫活性。

发光的Photorhabdus luminescens是一种感染了Heterorhabditidae家族昆虫线虫的杆状细菌。它通过分泌高分子量毒素复合物杀死昆虫。在这项研究中，小菜蛾幼虫被口服施用光合疟原虫进行生物测定。在Luria-Bertani（LB）培养基中孵育足够长的时间后，将发酵液稀释50倍和将上清液稀释5次后观察到的小菜蛾的死亡率分别为18.89％和91.11％。在超滤（UF）膜处理后，截留物超过70 kDa时显示88％的死亡率。因此，发光假单胞菌的上清液具有杀虫活性，并且主要的杀虫毒素复合物的分子量超过70kDa。L9（34）Taguchi正交实验优化的培养基模式预测的杀虫活性水平在50倍稀释的发酵液和5倍稀释的上清液中分别为84％和119％。此外，在实验中，在100倍稀释的发酵液中杀虫活性提高到92.2％，在10倍稀释的上清液中提高到97.8％。测试的所有组合均显示出明显的致死迹象，包括肿胀，囊泡形成，细胞质空泡化和刷状缘膜溶解。因此，这些结果促进了发光假单胞菌0805-P2R作为有效控制生物小菜蛾的有效生物农药的使用。在实验中，在100倍稀释的发酵液中杀虫活性提高到92.2％，在10倍稀释的上清液中提高到97.8％。测试的所有组合均显示出明显的致死迹象，包括肿胀，囊泡形成，细胞质空泡化和刷状缘膜溶解。因此，这些结果促进了发光假单胞菌0805-P2R作为有效控制生物小菜蛾的有效生物农药的使用。在实验中，在100倍稀释的发酵液中杀虫活性提高到92.2％，在10倍稀释的上清液中提高到97.8％。测试的所有组合均显示出明显的致死迹象，包括肿胀，囊泡形成，细胞质空泡化和刷状缘膜溶解。因此，这些结果促进了发光假单胞菌0805-P2R作为有效控制生物小球藻的有效生物农药的使用。