昆虫食草动物,比如蚜虫,在植物上很常见,然而,它们如何与植物微生物群相互作用仍然是未知的。例如,对于广泛的细菌附生植物和潜在的蚜虫病原体丁香假单胞菌,蚜虫可以通过充当次要宿主或通过摄食和/或废物分泌改变附生生境来影响细菌种群。这里,我们检查了豌豆蚜虫,Acyrthosiphonpisum,可能会影响丁香假单胞菌的附生种群。首先,我们量化了21种不同丁香假单胞菌菌株中无蚜虫的附生生长能力和对蚜虫的毒力。然后,对于八种性状不同的菌株,我们评估了蚜虫的存在对附生细菌生长的影响。在某些情况下,丁香假单胞菌从蚜虫的存在中受益匪浅,细胞倍增高达3.8倍。这种益处与菌株性状无关,而是与初始种群密度相关;较小的细菌种群从蚜虫中获得相对更多的益处,和更多的人口获得较少的好处。蜜露,蚜虫的含糖废物,在没有蚜虫的情况下,足以增加叶片上的丁香假单胞菌密度。我们得出的结论是,蚜虫蜜露有时可以增加丁香假单胞菌的附生生长,但是细菌可能无法从使用蚜虫作为宿主中受益。
AbstractInsect herbivores, such as aphids, are common on plants, yet how they interact with plant microbiomes remains largely unknown. For instance, for the widespread bacterial epiphyte and potential aphid pathogen Pseudomonas syringae, aphids could impact bacterial populations by serving as secondary hosts or by altering the epiphytic habitat through feeding and/or waste secretion. Here, we examined whether the pea aphid, Acyrthosiphon pisum, could influence epiphytic populations of P. syringae. First, we quantified epiphytic growth ability without aphids and virulence to aphids across 21 diverse P. syringae strains. For eight strains that varied in these traits we then assessed the influence of aphid presence on epiphytic bacterial growth. In some cases P. syringae benefited significantly from the presence of aphids, with up to 3.8 times more cell doublings. This benefit was not correlated with strain traits but rather with initial population densities; smaller bacterial populations received relatively more benefit from aphids, and larger populations received less benefit. Honeydew, the sugary waste product of aphids, in the absence of aphids was sufficient to increase P. syringae density on leaves. We conclude that aphid honeydew can sometimes increase P. syringae epiphytic growth but that the bacteria may not benefit from using aphids as hosts.