Geographical Variation in Bacterial Community Diversity and Composition of Corythucha ciliata

The sycamore lace bug, <i>Corythucha ciliata</i>, a globally invasive pest that damages <i>Platanus</i> spp., harbors a bacterial microbiome that may help it adapt to different geographical environments. However, the geographical differentiation patterns of its bacterial community and the underlying driving mechanisms remain unclear. In this study, we standardized rearing of three <i>C. ciliata</i> populations (collected from Beijing, Lianyungang, and Nanjing) for three generations to reduce immediate environmental interference, then analyzed their bacterial communities via <i>16S rRNA</i> gene amplicon sequencing. The principal coordinate analysis revealed a significant separation of the bacterial community in the Nanjing population, while the Beijing and Lianyungang populations were more similar. Bacterial alpha diversity followed the gradient of "Nanjing > Lianyungang > Beijing", with the Nanjing population exhibiting significantly higher species richness and evenness than the Beijing population. All three populations shared core bacterial taxa (e.g., phyla Proteobacteria, Bacteroidota; genera <i>Cardinium</i>, <i>Serratia</i>), but their relative abundances differed significantly: <i>Cardinium</i> dominated the Beijing population (50.1%), <i>Serratia</i> dominated the Lianyungang population (45.86%), and the Nanjing population harbored unique dominant genera such as <i>Sphingomonas</i>. For the three target populations, monthly average temperature and wind speed were positively correlated with bacterial diversity, while latitude was negatively correlated (Pearson correlation coefficient: 0.6564 < |<i>r</i>| < 0.7010, <i>p</i> < 0.05). Core bacterial functions (e.g., substance transport) were conserved across populations, whereas differential functions (e.g., detoxification, lipid metabolism) were linked to geographical adaptation. This study confirms the climate-driven geographical differentiation of the <i>C. ciliata</i> bacterial community provides insights into the "insect-microbiome" interactive invasion mechanism that is present here.