Host Plant Switching and Viral Infections Reshape the Microbiome of the Aphid Vector <i>Aphis gossypii</i>

Insect-associated microbiomes constitute a crucial component of the physiological fitness of insects. Thus, the structure and composition of the bacterial community may have important implications for the performance of insect pest vectors, and in turn, for plant crops. However, the relative effects of the transition between host plants and feeding on virus-infected plants remain unclear. In this study, we examined the bacterial community structure and composition of the cotton-melon aphid, Aphis gossypii Glover, in response to transitions between cucurbit plant species and melon plants infected by persistent (cucurbit aphid-borne yellows virus, CABYV) and nonpersistent (watermelon mosaic virus, WMV) plant viruses in single and mixed infections. Our 16S rRNA gene sequencing analysis revealed that bacterial diversity was greater in aphids feeding on melon than those feeding on cucumber, and re-established when returned to melon. This microbiome structure alteration was mainly caused by shifts in the relative abundance of facultative symbionts, such as Arsenophonus and Sphingomonas. Furthermore, viral infections significantly reduced microbiome diversity compared with that in healthy plants, with the lowest diversity observed in aphids feeding on mixed-infection plants with cucurbit aphid-borne yellows virus and watermelon mosaic virus. A notable negative correlation between Buchnera and Arsenophonus abundance was identified and validated by quantitative polymerase chain reaction in those viruliferous aphids, suggesting a compensatory mechanism and that viral infections may modulate endosymbiont interactions. This study underlines shifts in the aphid microbiome, which could provide insights for further investigation of microbial resource-based solutions to control aphid pests and associated viral diseases in agriculture. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .