Faculty of Agricultural, Environmental and Food Sciences, Free University of Bozen-Bolzano, 39100, Bolzano, Italy.
Department of Botany and Zoology, Faculty of Science, Masaryk University, 60200, Brno, Czech Republic.
Sci Rep. 2023 Sep 25;13(1):16038. doi: 10.1038/s41598-023-43130-w.
Most sap-feeding insects maintain obligate relationships with endosymbiotic bacteria that provide their hosts with essential nutrients. However, knowledge about the dynamics of endosymbiont titers across seasons in natural host populations is scarce. Here, we used quantitative PCR to investigate the seasonal dynamics of the dual endosymbionts "Candidatus Carsonella ruddii" and "Ca. Psyllophila symbiotica" in a natural population of the pear psyllid Cacopsylla pyricola (Hemiptera: Psylloidea: Psyllidae). Psyllid individuals were collected across an entire year, covering both summer and overwintering generations. Immatures harboured the highest titers of both endosymbionts, while the lowest endosymbiont density was observed in males. The density of Carsonella remained high and relatively stable across the vegetative period of the pear trees, but significantly dropped during the non-vegetative period, overlapping with C. pyricola's reproductive diapause. In contrast, the titer of Psyllophila was consistently higher than Carsonella's and exhibited fluctuations throughout the sampling year, which might be related to host age. Despite a tightly integrated metabolic complementarity between Carsonella and Psyllophila, our findings highlight differences in their density dynamics throughout the year, that might be linked to their metabolic roles at different life stages of the host.
大多数吸食树液的昆虫与内共生细菌维持着专性关系，这些细菌为宿主提供必需的营养。然而，关于自然宿主种群中内共生体丰度的季节性动态的知识还很匮乏。在这里，我们使用定量 PCR 技术研究了自然种群中梨木虱（Cacopsylla pyricola）（半翅目：木虱科：木虱科）中双重内共生体“Candidatus Carsonella ruddii”和“Ca. Psyllophila symbiotica”的季节性动态。在一整年的时间里，我们采集了梨木虱个体，涵盖了夏季和越冬两代。内共生体的密度在若虫中最高，而在雄性中则最低。卡森氏菌（Carsonella）的密度在梨树的营养生长期保持较高且相对稳定，但在非营养生长期显著下降，与梨木虱的生殖滞育期重叠。相比之下，Psyllophila 的丰度一直高于 Carsonella，并在整个采样年度内波动，这可能与宿主年龄有关。尽管 Carsonella 和 Psyllophila 之间存在紧密的代谢互补性，但我们的研究结果强调了它们在一年中的密度动态存在差异，这可能与其在宿主不同生命阶段的代谢作用有关。
