Abstract
Host species, locations, and diet can significantly impact microbial diversity and community in insects. Several ladybird beetles are known as key predators and potential biological control agents for aphids. However, there is limited understanding of how host species, locations, and aphid prey influence the microbial diversity and community of aphidophagous ladybird beetles in natural environments. In this study, we collected 74 samples of ladybirds and their aphid prey from various locations in Guangxi, China, and sequenced the 16S amplicons to investigate differences in their microbiomes. The dominant genera in the ladybird samples, Bacteroides and Alistipes, were rarely reported as predominant in other ladybird populations, indicating a unique genus-level microbial community pattern in Guangxi. Alpha diversity indices and Bray-Curtis distances varied significantly among ladybird species. Abundance analysis revealed that the relative abundance of dominant bacteria in aphidophagous ladybirds differed significantly among different ladybird species and locations. Although the primary and facultative aphid symbionts differed among aphid samples from various populations and locations, they had minimal direct impact on the microbial community of the aphidophagous ladybirds, being sporadically detected in the corresponding predator samples. Our findings provide insights into the microbial communities of ladybirds and aphids in sympatric and distinct field environments, highlighting the plasticity of microbial abundance in aphidophagous ladybirds across different ladybird species and locations, as well as the low retention rate of specific aphid symbionts in ladybird predators.