The use of belowground microorganisms in agriculture, with the aim to stimulate plant growth and improve crop yields, has recently gained interest. However, few studies have examined the effects of microorganism inoculation on higher trophic levels in natural conditions. We examined how the diversity of phytophagous insects and their natural enemies responded to the field-inoculation of soybean with a model arbuscular mycorrhizal fungus (AMF), Rhizophagus irregularis, combined with a nitrogen-fixing bacterium, Bradyrhizobium japonicum, and a plant growth-promoting bacterium, Bacillus pumilus. We also investigate if the absence or presence of potassium fertilizer can affect this interaction. We found an increase in the abundance of piercing-sucking insects with the triple inoculant irrespective of potassium treatment, whereas there were no differences among treatments for other insect groups. A decrease in the abundance of the soybean aphid, Aphis glycines, with the double inoculant Rhizophagus + Bradyrhizobium was observed in potassium enriched plots and in the abundance of Empoasca spp. with potassium treatment independent of inoculation type. Although it was not possible to discriminate the mycorrhization realized by inoculum from that of the indigenous AMF in the field, we confirmed global negative effects of overall mycorrhizal colonization on the abundance of phytophagous piercing-sucking insects, phytophagous chewing insects, and the alpha diversity of phytophagous insects. In perspective, the use of AMF/Rhizobacteria inoculants in the field should focus on the identity and performance of strains to better understand their impact on insects.

中文翻译：

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菌根定植对大豆田植食性昆虫及其天敌的影响。

在农业中使用地下微生物以刺激植物生长和提高作物产量，最近引起了人们的兴趣。然而，很少有研究检查微生物接种对自然条件下较高营养水平的影响。我们研究了植食性昆虫及其天敌的多样性如何对大豆田间接种模型丛枝菌根真菌 (AMF)、不规则根霉、结合固氮细菌 Bradyrhizobium japonicum 和促进植物生长的植物产生反应。细菌，短小芽孢杆菌。我们还调查了钾肥的存在或不存在是否会影响这种相互作用。我们发现无论钾处理如何，三重接种剂都会增加刺吸昆虫的数量，而其他昆虫组的处理之间没有差异。在富含钾的地块和 Empoasca spp. 的丰度中观察到大豆蚜虫、甘氨酸蚜虫的丰度下降，双接种剂根瘤菌+慢生根瘤菌。钾处理与接种类型无关。尽管不可能将接种物实现的菌根化与田间本土 AMF 的菌根化区分开来，但我们证实了整体菌根定植对植食性刺吸昆虫、植食性咀嚼昆虫的丰度和 α 多样性的全球负面影响植食性昆虫。从角度来看，在现场使用 AMF/Rhizobacteria 接种剂应侧重于菌株的特性和性能，以更好地了解它们对昆虫的影响。