Microbiome of the Aphid Genus Dysaphis Börner (Hemiptera: Aphidinae) and Its Relation to Ant Attendance

SIMPLE SUMMARY: Many organisms are supported by cooperative bacteria, the so-called microbiome, which enhance their survival abilities. Aphids also have many bacterial symbionts, providing them with nutritional components as well as protection against environmental conditions and pathogens or natural enemies. Similar relation connects aphids with ants, so the mutual reliance of bacteria and ants may be exclusive to aphids. Also, the relationship of aphids with their host plants may be decisive in shaping the aphid microbiome. Here we showed, that aphids attended by ants have less but more diverse bacterial symbionts while aphids on their primary host plant, where they reproduce sexually, have fewer symbionts than on secondary host plants. The results suggest that symbiosis with ants may serve aphids to replace some functions of bacterial symbionts. However, it seems that the relationship between aphids and host plants is a much stronger trait influencing the composition of the aphid microbiome. ABSTRACT: Among mutualistic relationships of aphids with other organisms, there are two that seem to be of major importance: trophobiosis with ants and endosymbiosis of bacteria. While the former is well studied, the latter is the subject of an increasing amount of research constantly revealing new aspects of this symbiosis. Here, we studied the possible influence of ant attendance on the composition of aphid microbiota on primary and secondary hosts exploited by the aphid genus Dysaphis. The microbiome of 44 samples representing 12 aphid species was studied using an Illumina HiSeq 4000 with the V3-V4 region of 16S rRNA. The results showed a higher abundance of common facultative symbionts (Serratia, Regiella, Fukatsuia) in aphid species unattended by ants, but also on secondary hosts. However, in colonies attended by ants, the general species composition of bacterial symbionts was more rich in genera than in unattended colonies (Wolbachia, Gilliamella, Spiroplasma, Sphingomonas, Pelomonas). The results indicate a huge variability of facultative symbionts without clear correlation with ant attendance or aphid species. The possibility of multiple routes of bacterial infection mediated by ant-made environmental conditions is discussed.